Dr Yvonne Aitken, agricultural scientist (1911-2004)

Dr Yvonne AitkenDr Yvonne Aitken received a doctorate in agricultural science from the University of Melbourne, and continued to work there throughout her career. Her research centred on how plant species adapt to climate through the differing flowering responses of early and late varieties and how this in turn affects the growing period (ie, days from sowing to flower initiation, to first flower and to ripe seed).

She first studied the effect of daily temperature and photoperiod on a group
of nine well-known agricultural species (three legumes, six cereals and grasses) sown at Melbourne (latitude 38°S) at intervals during the year. A further set of the same varieties was grown in diverse climates in other world agricultural regions during 1963, 1970 and 1975, with the unique data collected personally by her.

She has contributed to the search for better crop and pasture species for Australia by increasing our understanding of genetic factors within a species that control reproductive development in different seasons and climates.

Teachers' notes to accompany this transcript.
You can order the DVD from the Academy for $15 (including GST and postage)


Interviewed by Ms Nessy Allen in 2001.

Contents


Approaching science with keenness and delight

Yvonne, would you tell us about your early life?

I was born in Horsham, Victoria, in 1911. I can remember people coming to the door during the Depression, wanting to chop wood so they could get something to eat. It was terrible.

I was the elder of my parents' two children, and whenever the family had to move for my father's job as a bank manager we were supposed to help – consequently we often found some very interesting things under the furniture seats. My parents were both interested in education, especially of their offspring. And my mother, as a schoolteacher, knew how keen the Convents of Mercy were for education.

Were you interested in science as a child, and at school?

At first I didn't think about 'science' by name; it was just there. I was naturally curious and science appealed to me when it came into my schooling, such as when we tried to do experiments. I had some good teachers at the convent schools.

For the last two years of school I won a scholarship to a branch of the Convent of Mercy that had come from Ballarat to St Arnaud, a country place where we lived. The school didn't have any equipment or place where physics or chemistry could be taught, and the staff were not skilled in teaching it. But the younger nuns had been encouraged to begin their university training in science by going to the School of Mines at Ballarat, where they were able to do geology and botany, which meant I could do those. I was keen to get something to do with science – and I was interested in farming anyway, so I was delighted to get a scholarship to study agricultural science at the University of Melbourne. That was an important thing.

In a sense, then, did your career direction come by chance?

Oh yes. And it might not have gone further, because my parents knew nothing about this 'agricultural science' and they were very dubious, as were the nuns too. Fortunately, one of the nuns rang her brother, who was an expert on irrigation of lucerne and high up in the Department of Agriculture, and he said, 'Of course it's all right for women. We need scientists.'

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Getting around the drawbacks

How did you manage zoology, physics and chemistry in first year at university, when you had not done them at school?

That was a distinct drawback, but fortunately there were very good women demonstrators attached to the practical side. Their sympathy for people who started without those skills made all the difference for me in passing my year. The botany was all right; zoology was fairly close to it and there was a good demonstrator; but it was only thanks to the demonstrators that I could understand physics and chemistry.

Unfortunately, I got ill towards the end of the second year – the year when we went down to Werribee Research Farm for half the week to learn the practical side of agriculture. I was invalided home to St Arnaud, and had to go to bed and be nursed by my mother for quite a long time. I managed to recover all right, but it took about 2 years and I did not get back till 1934 and '35 to finish. I was glad my scholarship continued while I was away, because otherwise we couldn't have afforded to pay for board for me in a residence at the university.

I understand that Professor Wadham, the head of the Faculty of Agriculture, helped you.

He was most helpful. He was very welcoming to start with. I was two weeks late in applying to be a student, and then my mother came down with me to begin. Hearing that I didn't have any place to stay, Professor Wadham rang up the principal of Janet Clarke Hall (one of the only two women's colleges at the university at that time) and so I was able to have a small place that was spare.

Later, when I was home ill but beginning to recover, I wrote to Professor Wadham for ideas about what I could work on in preparation for getting on in another year or so. Having come out to Australia from England, he was most interested in our different kinds of vegetation and also the native grasses. He said, 'Well, you'll have native grasses around the countryside where you are. Try and find out about them, study them, and that could be your talk in the fourth year.'

That gave me something very interesting to do. My family met one or two of the farmers, who gradually introduced me to other people. Some were extremely interested in getting the proper names of the grasses and a few brought in samples that I could grow in the garden and so on. And I could ask the farmers about managing their farms, and about whether the sheep had lambs or not, all that sort of thing.

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An introduction to subterranean clover

When you graduated in 1936, what were your plans?

I still wanted to train as a scientist. Professor Wadham told me to go to the library and spend a bit of time looking up the different types of research that I might like. 'Come downstairs in a few hours,' he said, 'and we'll talk about it.' I remember very well that he scarcely glanced at the long list I had made of all sorts of different angles, from animals to plants to microbiology. He just said, 'I've got an invitation from the Department of Agriculture. They've got something very interesting at Burnley Gardens but not enough people to help. Would you like to go and see if you'd like that?' That started almost the whole of my career.

My parents had to move to Melbourne, so I had to have a bit of extra money, but Professor Wadham found me a small annual grant that he kept on expanding from year to year for a while. And a bit of money from demonstrating in botany and other subjects made me enough to keep going.

What was the project Professor Wadham suggested to you?

It was on a small clover that was promising from the point of view of adding to the grazing pasture in a range of climates – from the better country even up into the Mallee, where there was only a very short and erratic growing season. Its name was subterranean clover, because of its peculiar burying of its seed. The only other crop plant that we know has this most unusual character is the peanut.

Subterranean clover is quite a small plant which has three leaflets and so belongs to the trifolium group. It is a legume, which means that it has got a capacity for having a symbiotic relationship with Rhizobium bacteria, which make nodules on the roots of the clover. (These are not a pathological attachment.) There is then a production of nitrogen, at a fertiliser level, available to the plant in return for giving housing to the bacteria. That gives greater value to the farmer because of the high protein of the leaf and because the nitrogen exudes to the soil when the plant – an annual – dies.

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When would the clover flowers grow?

Who were you helping at Burnley Gardens?

Mr Jim Harrison, a graduate of ours about 10 years ahead of me. He had started the collection of this strange little weedlike plant that had come quite accidentally into Australia and adapted itself to our climate. Nobody else had done any work on it. He collected subterranean clover samples from different parts of Victoria, mainly the dairy country, and also wrote over to Western Australia in order to collect samples found there accidentally. He had a real enthusiasm to follow the wonderful exploits of Vavilov, a scientist in Russia who after the war ran expeditions to other countries to collect the cultivated types of food plants for study. Like Jim Harrison we had been trained on Vavilov as a most important part of agricultural science, and as students we were fascinated that these expeditions were doing something so very practical. They showed that when you grew plants of the one species beside each other, there was an enormous natural variation which was used by human beings to get a short growing season, good variety and a later one.

Harrison had found some of these plants on the railway line. Perhaps if he started collecting there he might find this wonderful variation, even though it hadn't been through human hands. It became a wonderful enthusiasm for him, and extremely striking to the Agriculture Department. He had done 7 years on this before I came along and his first collectings had shown a magnificent spread of variation, which was why the department now wanted the whole research written up and available for other people. But Harrison and his helper, Frank Drake, always had other things to do and they couldn't get any further. They were getting results but it was just stagnant. So I was getting a chance to work with them.

I was to help check over their results, encourage getting the results into graphs and tables that could be read by other people, think about what evidence there was, and find out more about the biology of the subterranean clover, especially its capacity for a wide range of flowering time – plenty of work, you see. The first thing was to look at plants that had been sown year after year for 6 years at the same time: the typical sowing time for farm crops, from April, in autumn when the rains might have come, to about November/December, when the dry seed had been formed and there would be drought afterwards. When I looked at the data, it was excellent – 6 years, and the plants were doing the same thing every year. We could see the groups: the one that started to flower early, in middle August, which was still winter; the next group a month later, at the beginning of spring; the next one in middle spring, October. I had never before seen plants in that extremely wide range growing side by side.

But we didn't know how the plant reacted to any other climate. The year I started to help at Burnley, we decided we must test out the plants for that. In the Australian set-up, planting seeds of the same variety every month throughout the year would be like going through about three different climates from winter to spring and summer and autumn. That would tell us how the plant was reacting and we might begin to see what factors were making it behave in different ways. And so we started a set of another 4 years. It was from that second method, that time-of-sowing experiment, that we got the clue about the responses of the plant to the temperature as one factor, as it changed, and also to the hours of light in the day – the other factor, which was only just being discovered all over the world.

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How long then to maturity?

I think you were also working on how the time taken to reach maturity would vary.

That variability of plant maturity types was a fascination to me – the fact that one type got quite rapidly from sowing to flowering and the finish of the ripe seed, which would then fit it for a shorter growing season in places, but another was so long about it that it was not available for another couple of months. It needed all that extra time to fill out, to make the leaves and the seed and get to the finish of its growing period.

Our training on wheat and the other cereals in the agricultural property in Victoria had been nearly all on wheat and the wheat breeding necessary to get high yields in both the rapid-developing plants for the drier country and the ones that had a longer growing season. Here, though, was a little pasture plant with a capacity for choice naturally there. The problem was then to find out a bit more about what the plant was reacting to. And my interest in that second method we were using at Burnley – on the time of sowing and the plant's reaction – was the start of my own particular research, both in how I helped there and in what I was able to do in the next several years, getting more detail about the controls.

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The problem of clover hard-seededness

The work for your masters degree was on hard-seededness in clovers. What led you to study that?

That was a kind of sideline that I got interested in. Nobody else had done much about it except someone in Canada, on another kind of legume.

It is just a typical character of clovers, and many other legumes like wattles, that they make large percentages of hard seeds whenever they are producing seed. But a farmer might be trying to increase the value of the clovers by harvesting the seed and sowing it. Then to have a high percentage of hard seeds, and so a very low return of germination, is a great drawback to starting the clover off as a crop or a pasture plant.

The problem of the hard seeds was a particularly annoying one. In a way, it isn't a problem if you have machine harvesting, because scratching the seed coat makes it able to react to water. The trouble comes when a hard seed is in the soil. It may take several years to germinate and you are not getting the benefit of the plant growing. So the hard-seededness of a valuable type of clover has to be thought of in terms of how the farmer can have more control over the germination.

I began by taking sections of the seed as it was developing after fertilisation in the seed cell itself – which quite often had been buried in the soil, in a little cluster of about three or four seeds in the burr that was the way the plant developed after fertilisation. From a section I could see the structure on the outside layer, a kind of waxy covering. If that was continuous, no water could get in to the seed and it could not germinate. So the first thing was to define the reason for the hard-seededness.

The second thing was to find out what conditions would make the seed soften naturally in the soil. That was a much harder answer to define, but it came out of finding that the structure had a slight peculiarity. You had a continuous smooth surface of a single layer of cells, vertical to the inside part of the tissue, but in one spot a little bump protruded like a pimple. And that, when you took the section, was three-times-longer cells pushing out the waxy covering. (It was there in any seed, although because it was small you had to look carefully.)

I tested those seeds first of all in temperature changes. After all, a seed in the soil wasn't going to be scratched in any way, and the only thing that might affect it was reacting to alternating temperatures, especially daily for about a month or so – as occurs particularly at the end of summer when you are changing over to winter. I experimented by using a refrigerator and heaters, and changing the position on these seeds during the day. Keeping them in water, you could watch what happened. When you gave them a wide enough alternation, like they get in the autumn, lo and behold, after a few weeks you would find that a few hard seeds had become soft, and so on. That proved to be the answer to what happened in the soil.

But to gain access to being able to change it, you had to learn a bit more about what happened in the plant itself. Were there certain parts of the timing of the plant that meant those seeds that came from the first-formed flowers made themselves a bit harder than the ones from flowers that had formed along the runners about a month later? (The sub clover is a flat-growing plant whose leaves and the flowers develop on runners in contact with the ground.) Well, that is indeed what we found. We got a clue that there was something to do with the amount of time the plant took to produce that seed from the flower part and get it to full size. And it showed up also when you picked out the seeds: the ones from the flowers that had formed first would usually be distinctly bigger than those from the ones that had formed last, just before the plant died. Put them in water side by side, and the seeds that were in the most recently formed flowers tended, as a significantly higher percentage, to be softer. So that at least gave the answer, but it didn't help the farmer.

We went on a bit with the details, testing what sort of temperature range made the difference and at the same time looking at whether some of the varieties that we were testing, with the large range we had at Burnley, were less hard-seeded than others. We found several, here and there, that were. But that wasn't any help to the farmers either, because those seeds weren't available for them to buy and use. Nevertheless, that was about the most useful pointer I got out of the research. It was able to be written up, and it made me a paper that had to be given to the Royal Society. Also, fortunately, I could submit it for a Masters degree – which I got in 1939.

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Harnessing field peas to wheat production

You were working on another project at the same time as the clover, weren't you?

Yes. In 1938 I had got tangled up with a breeding problem for field peas. That probably sounds odd now, but there was a real crisis in the Agricultural Department of Victoria. For 50 years the total wheat yield had been declining steadily, even though new varieties were being produced and put in the trial. The decline was so dreadful that the department rang up Professor Wadham, asking what could be done.

They worked out that the only way to improve it was to bring in a crop legume: a legume with the same capacity as clovers for getting extra nitrogen into the soil, and giving a good enough yield to be grown. If the farmer put that in the rotation that wheat always needed – one year of wheat, a year of another crop, a year's rest and then back to the wheat – that might reverse the yield difficulty. And so I agreed to start a breeding program on field peas for the Mallee and the Wimmera.

It turned out to be quite long term, actually, because in a breeding program you have to find and test lots of varieties to see which have any value as parents for crossing. We had very few varieties in Australia and I had to get any varieties of peas I could from Europe and elsewhere, particularly from where they had been bred for difficult climates like shortness of growing season, due either to frost or to drought. Gathering that together took quite a few years, and then in the next year or two I was able to start doing the crossing. And I eventually got two varieties that could be bulked up for commercial use.

As I began to get the collection in my hands for growing, I started research out at Burnley Gardens. It was nearly ruined the first time, because wild pigeons came in and got most of the germinating seeds, so I needed somewhere else to grow my material. The discussion ended up with an offer of Dookie College. Not only did it have fewer pigeons but it had a bit more capacity, with a cage in which I could grow some of my crosses, and paddocks where the peas could perhaps be put under netting for the time being. 'Anyway,' I was told, 'that's all we've got to give you. You can go up to Walpeup, which would be another good place to start the seeds for the varieties. That's the choice.' And so that's what we did.

We could do the crossings down here, but to begin the actual growing and selection we moved up to Dookie College. As soon as I found early plants out of the crosses, they were put together to get just enough seed for a plot (each plot was very small, about a metre square) and then that was planted at Walpiup and its equivalent was grown at Dookie as well. Walpiup was extremely important as the testing place for the plant's survival. Our first few varieties ran into trouble because of a drought, but the next year, 1939, was very good. During those 20-plus years at Walpiup there were several drought years, but I did get evidence here and there of worthwhile varieties.

I crossed a good parent variety we had, an ordinary one which grew early in both the Mallee and the Wimmera, with something that had come from Ethiopia as a packet of seed – it landed on the desk at Burnley Gardens, was given to me because I was working on peas, and turned out to be slightly better at coping with drought than the ordinary one. Out of that came the two varieties that we decided, as a side outcome of the breeding program, to make commercial.

I've been told that some students who were helping you christened you Miss Peabody, because of the sun-hat you wore all day as you worked.

Oh yes, that was a great joke to the local students. Very few had hats in those days.

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Increasing yields: a teaching post and more pea research

When did you join the permanent staff of the university?

In 1945, at the end of the war. Professor Wadham was deeply involved in the planning for soldier settlements, especially the rehabilitation and proper training of soldiers who wanted to farm, and couldn't spend time doing his ordinary lectures on the agronomy and the plant side of things. Because I had been brought in to practise that for the previous few years, the order was, 'You do the teaching, and I'll put you on the permanent list.'

Did that keep you in Melbourne, or were you still working elsewhere as well?

I was carrying on the pea-planting yield tests in the Mallee and over in Dookie. And there were several planting opportunities to test out some of my varieties, such as at the Waite Institute in South Australia and also at Horsham in Victoria, where Longerenong College had become a wheat-breeding centre. They were just occasional but they gave me more experience of the actual reactions to the growing seasons.

Very little work had been done toward higher yields in the canning peas or vegetable peas – similar kinds of peas needed for the industry – because the varieties were brought in from the United States, England and so on. We wondered, 'Could we breed for increased numbers of full pods in the pea plant?' The places where the mechanical harvesting was going on were in the wetter parts of Victoria, the more southerly parts in the Western District and over in Gippsland. We had to establish the varieties that we were wanting to test out. Growing them in the small plots to find out their yield under those conditions meant travelling for sowing and harvest, but the department's research farm to the east of Melbourne provided a closer place for the observation plots that I needed.

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Studying growing seasons in two hemispheres

When did you first go overseas for research?

That was in 1955. Professor Wadham decided to retire early because of illness, so it became urgent that I take some leave beforehand. He asked me suddenly, 'How about having a leave next year?' and I had to think what I wanted to do.

My experiences up to that time had made me keen to learn much more about the pea crop in different parts of Europe, from the Mediterranean up to the top end of Sweden. Also, I was keen to plant my little set of early, middle and late pea varieties at the Cambridge Agricultural Faculty area, to get first-hand information about how they reacted to the longer hours of daylight and the cooler spring and then compare that with my data from the Melbourne situation. And I wanted to get in touch with Dr Cooper, at the Plant Breeding Station in Wales. In much the same way as I was looking at sub clover, he had begun to look for the characters controlling the responses of rye-grasses for flowering. Of course, in the process of going from Greece up to northern Sweden I took every opportunity to visit research stations working on the peas, and the very few that had begun to work on pasture plants.

You mentioned getting data in Cambridge to compare with what you had from Melbourne. What problems were you hoping to solve?

They related mainly to climate differences. One problem was the very short growing season. In trying out and testing varieties, the idea was to test only one character, one situation at a time. So in thinking about a short growing season you began to wonder, 'Now, what happens when you go up the side of a mountain?' That would be the place to put your plots at, say, three different levels, plant them on the same day or two, and find out how the same varieties reacted to increasing cold. Then you would think, 'And what can you do in Australia?' This applied to the sub clover very much, as soon as we found that at least the late one refused to get into the flowering state when the temperature was too high. You'd suppose that would be controlling their use in Queensland, so I got my friends in the research side there to plant seeds and so on as part of my sub clover research. And thinking about Australian temperatures, I realised that to get your natural higher temperature you'd have to go miles away from Melbourne, even up to the Northern Territory.

As I started looking out for those different kinds of growing seasons in Australia, another side of the same thing occurred to me. What about different altitudes? There is very little to choose from in Australia, but surely an island in Hawaii would give you the range of temperature. You could try California, too – although they are at the same latitude as we are, their mountains provide the necessary range in temperature. So I was beginning to think of that kind of combination.

My 1955 leave enabled me to do the first such test that I could do easily. Because Cambridge is at a latitude of 56 degrees north, whereas we are at 38 degrees south, I could get a set-up for the spring growth in the higher latitudes to contrast with what I knew happened down here. It got to be very much a pressing fever in my mind. The chance of a sabbatical leave gave me that first experience and led to the idea that a plan, a group of species which would be limited but representative of both your crop and your pasture sides of agriculture, would be very worthwhile.

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Widening cooperative climate plot research

In a sense you had cooperative growing arrangements to support your work in Australia. Were you able to get similar arrangements in other countries?

Yes. When I took my 1963 sabbatical I went to visit four important people who were going to help me with getting some more information about the reactions of my set of experimental species to different climates.

The first one was Dr Heise, from the Carnegie Institute of Washington, in California, who had many years of experience on growing some of the native species of plants in California at three different levels of altitude. Concentrating on perennials that could be subdivided, rather than annuals and seeds, he grew rooted divisions of the same plant at each level. Since they had the same genotype, any differing reactions were their responses to the range of temperature – from sea level, with temperatures like those in Melbourne, to the middle level at about 4000 feet, behind a reservoir for San Francisco, and then to 10,000 feet (3000 metres) in the mountains along the edge of the driest states. He was quite interested in my idea that I could sow plants from my set of varieties and species in that wonderful range of altitudes and watch for the reactions that showed up, and he even promised me a patch in the office for a desk.

Another person was someone I had met at a conference, who came from the Oregon State University at Corvallis. He was interested in the same experiments and promised to grow at the times I asked for and take the observations. Also, there was Dr Cooper, whom I had met at the Welsh Plant Breeding Station in 1955. He was able to say yes, he would do the plantings for me, and not only in spring but in autumn, which meant that I got the local information about the two seasons. And Dr Britton, in the University of Hawaii, could help me greatly with the problem of growing the same genotype at different levels up the side of a mountain.

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'Every single variety was reacting to temperature'

So you continued to develop your climate plots. Just what work did you do on them?

The climate plots were designed to give me information about how fast the actual varieties grew and developed in the real environment of the farming field, where the crops are actually grown or the pasture plants are actually eaten by animals. This situation is particularly valuable because that type of data is mostly missing in the usual research on the factors affecting the development of plants – the experiments are done in laboratories and there is such a rush on the equipment that the time to get your information can't be spared.

I found that flower initiation in the early-maturing varieties was less affected by the climatic factors than in the slowest or the late ones, which meant you could generalise and say that the temperature as such was a major factor in the rate at which a variety would grow from the beginning to the end. That variety would be responding according to its genotype, and that genotype would be reacting according to the climate, involving both the temperature and the day length of that situation. But day length was more exceptional as a factor in the plants' reactions. A number of varieties were not sensible to the photoperiod, but every single variety was reacting to temperature (sometimes in opposite directions). That was a great discovery from the field point of view.

As a result of this work in 1969 the degree of Doctor of Agricultural Science was conferred on you.

Yes. I was surprised that I had managed to get to that stage after so many years, but the conferring of that doctorate was a great pleasure.

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Plant sensitivity to the photoperiod

Having found out how important temperature was, were you able to follow up the significance of the photoperiod as well?

Yes, working largely in Peru and the highlands of Mexico, and in Alaska. I had a few plant varieties that were sensitive to the photoperiod and I used the contrasting environments to get evidence on how they would react when they were grown in the highlands of Mexico at about 12 hours' daylight in the summer, and by contrast in Alaska in the spring/summer, which got to 24 hours. I spent five months in Alaska first and then came down to the Mexican highlands to sow duplicate seeds of the varieties in that climate, where I spent the final five months or so of the year's leave. The sensitive varieties gave most satisfying slowing-up evidence in Mexico. They were so retarded by the low number of hours a day that they took three times as long to get to a given stage as they did in Alaska.

I took the opportunity also to travel to universities and agricultural research institutes in the United States, southern America and Europe for discussions with scientists working on the physiology of plants suited to short growing seasons.

In 1975 I was able to go again to Mexico: during my last leave, which was only six months instead of a year, I went to CIMMYT, a research organisation outside Mexico City that was one of the first to deal with the major food crops of the world. It was concentrating on wheat and maize, so I was able to plant a second part of my plan and research on maize. I had done the first part in Melbourne 2 years before, growing a range of the maizes from the high altitude section of the mountains in Mexico and Peru and also other varieties in between, that I got as samples, and some Australian ones. Being able to repeat that experiment by planting at CIMMYT gave me the contrast between how the plants developed in their original location and how they developed in Melbourne, in the temperate zone and in a day length that was two hours more in the summertime than in the highlands of Mexico.

The satisfying thing was that some of the varieties from Mexico which had been fairly fast-developing had a response inside themselves that made them go slow when they got the extra two hours of daylight in our summer. Other people had found that sort of thing, but I was anxious to get evidence of how the maize varieties would be acting in temperate places. (The action was actually the opposite to what the temperate ones had told me in my previous experiments.) Anyway, I got enough good data to write a reasonable paper on the effect of location on the maturity of the maize varieties.

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Maturity genotype versus climate reaction

You did a lot of research on plant flowering, publishing the outcome up to 1974 as a book entitled Flowering Time, Climate and Genotype. Can you summarise for me what you were trying to establish in your research?

I had been trying to understand the way the plants reacted to temperature and day length as climate factors, alongside finding out, wherever I could, other angles to the genetic controls of the rate of reproductive development. My climate plots had given me excellent indication of how powerful the climate reactions were.

When I began to analyse the data, comparing all that latitude work with the controlled environment work here, I was able to get some ideas about extra reactions that were inside the plant and needed to be added to the recipe of knowledge on their responses to the environmental factors. When I then compared my set of nine plants (some grasses, some legumes) it was a kind of revelation to see how they could be put together precisely on the pattern that they reacted to: how intensely they reacted to the kind of factors they had inside themselves and how important that was as a foundation factor inside them. I called it the 'tendency to flower': the changeover point from the vegetative to the reproductive.

I found I had some varieties that represented the presence inside them of a basic factor called 'intrinsic earliness' telling them when to react, and they were utterly uninterested in the climate. One of those was an oat plant I had collected – I wasn't expecting it, I was just looking for the earliest, but it was that sort of plant and so I could use it as a base on which I could class, in a grade of slight to intense reactions, the other varieties I had. The latest ones were always the ones that had very strong reactions to the climate set-up. Without that a plant was very early, and would be bottom of the possibilities. So for the first time I could think up a 'maturity genotype', a graded grouping of varieties. Another such variety, which I found pretty early on because of the collecting, was in peas. And the third one was in maize. It came from a plant breeder in the United States, and helped to make me so keen on getting maize.

Those three small varieties which were sensitive to an urge inside them to get quickly into the family state enabled me to say, 'No, they haven't got any climate responses. They are typically just very early ones.' Later on I found that a very common variety in peas called Dun Peas (from England, and grown here for split peas) was less anxious to get to that reproductive stage: it was just slow and you couldn't speed it up much at all. So here I had a picture, a way of describing and grouping plants, that other people could use – once they got down to the discipline of looking for the dates and sowing to flower initiation rather than going from sowing to flowering and ripe seed. They could benefit from that extra bit of skill and knowledge about how the plant changed over, under the climate influences, into the reproductive stage.

The next change, from flower initiation to flowering, could also be held up by a couple of small reactions, but not nearly as much as that very first one. And usually you could guess how many months, according to temperature, the plant needed from the flower to the seed – except for where I found a faster-developing one. It was a key thing for using Alaskan wheat. I grew an Alaskan wheat variety and our typical Australian one side by side. The Australian grain got hit by just one hard frost overnight, but the Alaskan one was perfectly all right. Therefore I could say that in wheat the character of being more speedy in ripening from a given time could be valuable in drastic climates where you can get hard frosts. And out of that work eventually came my book concentrating on the control side, with a lot of good evidence from my results.

I used to consult a very important friend in the soil section of our staff about my papers. His group was always interested in what I was doing from the plant side, and he himself was keen on clear and simple writing. (He wrote little newspaper articles about how important it was and how bad scientists were at it.) My last consultation with him took place when I was trying to write up the climate plots. I was planning to do two papers and asked would he look at them. His advice, though, was that people don't read papers. 'Make it into a textbook,' he said. Oh dear. That sounded impossible to me. But he agreed to help me by checking my writing and so on, and eventually the book was published and printed.

Meanwhile I had written to find out how I should apply for promotion. I found you had to show that you had done all sorts of things to be thought worthy, and apparently that book enabled me to be promoted to Reader, which happened in 1975. It was certainly a different process from my 1957 promotion, for which Professor Wadham had made arrangements just before he retired.

One review of your book stated, 'Dr Aitken's command of her subject as expressed in her book ensures that it will be the authoritative text in its field for years to come.'

Well, that comment was very gratefully received, but I don't think many people have read it because various other discoveries on such things came in with regard to the use of computers and genetic engineering. Over time it will still be useful, I hope.

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Sharing the word

You have contributed to some other books too, I believe.

Yes. I helped to write a textbook on agriculture. It arose because in those days teaching staff from the various faculties, together with secondary school teachers, were on boards for the secondary school examinations by which students got their university matriculation standard. Our group consisted of Jack Wilson and I, representing the plant crops and pastures side of teaching, and two good people on the animal management side: Dr Tribe and someone else. We four had to draw up the examination figures and we were landed with the exam papers at the end of the year. Also, the syllabus said the children had to learn how to make collections of plants and to name them, and they had to present that as their practical work, so we had to mark it for a pass or fail. That all resulted in a long list of how the students fared in the way of passing or failing. It was a surprisingly time-consuming job, but very interesting – particularly when we found that the teachers didn't have a good textbook. And some of the teachers weren't scientists but just school people who were interested and taught science when the schools couldn't find scientists to do it. I can remember Dr Tribe racing up the stairs and telling Wilson and me, 'We've got to make a textbook!' We had to agree that it was needed, and working together we made quite a good one, I think. (But it took a year or two to come out, much longer than we thought it would.) It was a good base for those teachers. We planned a refresher day after the exams, at the beginning of the next year. We kept exam papers with poor answers and good answers, and did all we could to increase the teachers' ability to do the job properly.

I did manage to be included in a particularly interesting book. A very good scientist based in Israel was interested in the flowering and development controls on plants. (He was on the horticultural side, but he had gone on for many years and was one of the leaders in the field.) He decided to make a whole set of books that drew together all the plant research being done throughout the world. He wrote to the people who had specialised in various angles on plant growth, and I was apparently selected because I had done a few papers concentratedly on pastures and agricultural plots – grazing and so on. I got this request just on the basis of the few species I had studied, so then I read up all the research I could find and tried to make a chapter connecting my findings with those of a few other people. And it was accepted. I was very pleased about that one.

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An excursion into wheat-growing history

One of your research sidelines was some fascinating work on the history of wheat-growing in Australia. Would you like to say something about that?

In 1962, in conjunction with the Department of Agriculture in Sydney, I worked on the problem of what kind of wheats were grown in the very first years of settlement. There were some records that people had planted Lammas wheat, a slow-developing one very commonly grown in England, where it came to harvest time somewhere around the end of the summer. That did not fit with my beginning knowledge on how a slow-developing wheat would go in Victoria or, probably, New South Wales. So I discussed it with my wheat expert friends in Sydney University and we worked out a plan of several of the most early-planted wheats which they would plant and grow for me in Sydney, at the same time as I did that in Melbourne. We managed to get Lammas wheat from the collections back in England, where it is still kept alive in the seed, and sowed it with Purple Straw, an old variety that in the early days in Australia was called an early variety, and also two of our modern wheats that were typical short-term ones in both Melbourne and Sydney. So we had the contrasts being grown in both places. The Sydney evidence would be the more important, of course, being relevant to the old days, but I would have backing-up evidence myself.

We got a season's results from that, showing that the Lammas wheat was very unlikely to have been any use. Because it was simply one of those very late, slow-growing ones, it took extra time to come into the stage of ripe seed – and in the Sydney climate, with not only a bit of drought but also an awful lot of rust afflicting the wheats that were being grown, it definitely was too slow. That made just a very little paper, an article, but it was an interesting trial in reconstructing the early days.

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Persuading maize to like cold weather

Besides your research on subterranean clover, peas and even early wheat varieties, you have done quite a bit of work on maize and have carried that on into your retirement years. What are you looking for in your maize research?

That research was based on my curiosity to see how a tropical plant would react, but it soon had relevance to the growing of silage for milking cows. Up at Kyabram, near the Murray River where irrigation was used for good pastures, the Agriculture Department had a development with the specific purpose of helping the dairy farmers in the area to feed their cattle to the utmost and so increase milk production. A Californian custom of growing maize for silage came out in a large-scale work as very important for milking cows' rates of producing milk, and that interested the department. So the idea was transported, along with the knowledge of varieties, to Kyabram research station.

I knew about the research there, but for a while I was too busy doing crossings to take much notice. Then I reached the stage when I needed a place in the cooler parts of Victoria to grow some of my crossings. I had planned and begun them with the idea of getting the very early varieties of maize from up and down the Andes, where they were grown by the local people, and applying them to practical use in Australia if we were trying to grow maize in places where it was cool but maize did not normally grow well.

I started off with seeds of some early-flowering varieties in my hand, and the information about how they grew. But they were fitted to the American Indian set-up, not ours. So I began crossing those early varieties with the earliest other one that I had here – one from Alaska, where it was grown for sweet corn. I told the Department of Agriculture people at Ballarat that I had this material, but the department thought the project was too vague. However, word reached a farmer from Bungaree, a potato-growing place near Ballarat, whose job was to grow crops and pastures to feed a dairy herd which his brother was looking after.

Hearing from a department circular about this wonderful new feeding device up at Kyabram, the farmer went up there, saw the magnificent crop of maize, found out its variety, came back and ordered seed for the next year, and grew it at Ballarat. He was disappointed, though, and rang up the Ag Department: 'What's happened? My crop is pretty good, I suppose, but it's only about half as high as the one at Kyabram.' The man at the other end knew a bit about the low temperature in Ballarat and explained that it would make a lot of difference to tropical plants – to the surprise and interest of the farmer, who had never travelled outside southern Victoria. The man in the department told the farmer about my young plants and the immediate response was, 'Tell her to bring all her work to our farm. We'd love to be in on that.' And I have since become friends with the farmer and his family.

Anyway, that's how I started, just a couple of years after I had retired. Because the work involved crosses of two fairly different kinds of genotypes, it took a long time before we could pick out something that was both early and sturdier than the ones from America. That eventually came after about 10 or 15 years of pulling out only the rarities, and now we're just finishing. We've got the variety, and it could be a help to farmers in cool places.

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Enjoying and linking interests

I can see that your scientific interests have never waned. Have you been able to find spare time for any other interests?

My mother was very keen on history, and that got into me very easily. Also, when I was convalescing from my illness I learnt how to do spinning, and eventually weaving, through the Country Women's Association – it had skilled people who would go round to different places to give lessons in such things. My father made me a spinning wheel from a bicycle wheel and other oddments, and later he built me a small loom. And I played around with getting dyes out of gumtree leaves and that sort of thing. So I had lots of occupations.

I also started playing round with painting, especially watercolours of places I'd been to. It was a wonderful change, actually, after whatever else you had been doing for hours, to just have a go – especially when it was to do with what you liked looking at.

I know you liked teaching. What did you most enjoy about that?

I particularly liked teaching when you had a few enthusiastic students in the class! But I liked the students in general; it was only when odd ones played up you got a bit sick of it. In general, though, even they could grow to be enthusiastic if there were a couple of leaders there already, and often the practical classes got them a little more interested – so long as it was important in the exam questions. (They had to have biochemistry, economics and other things that they quite often found very difficult.)

I had to devise a special course for civil engineering students. The university had made a new diploma for agricultural engineers, a special group who were taught civil engineering and then specialised on the design of machinery for agricultural purposes rather than bricks and mortar for houses or roads or so on. It was the only course being taught in Australia, so people might apply through their university training in New South Wales, Victoria or elsewhere. You might have just two or three students who came, without any biological subjects from their school days onwards. The very first one was like that: he had no biology at all in his brain but he had been appointed in charge of the peanut silos in Queensland. (They have to be near where the peanuts are grown so that when the nuts are harvested they can be kept in dry conditions and then gradually dried out for the seed to be removed.) He benefited very much. He was a keen student and he began to link it all up: for example, if you let water come into the silo, onto the peanuts, you would end up with mouldy stuff and everything would go to waste.

I designed the course to have much less talking than usual. I had so many lectures to give them, but beyond that they did experiments planting out some of the standard things like wheat, peas and so on in their plots here when they first began, and taking notes on the development over the next, say, six weeks. I then gave them something in the way of looking at the plant getting to the flowering stage and ripe seed, and also a bit of background on the agricultural management. I think that because they were looking at these things, growing them and having to give reports, it penetrated better than any standard work we could have done.

Yvonne, you have obviously made a most enormous contribution to your discipline, and I have very much enjoyed talking to you. Thank you very much for participating in this interview.

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© 2017 Australian Academy of Science

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