CROP IMPROVEMENT

Press, Volume XCVII, Issue 28701, 26 September 1958, Page 5 (Supplement)

CROP IMPROVEMENT

By

C. M. DRIVER,

Acting-Director, Crop Research Division, Lincoln.

VX/TIILE it i& possible to increase the yields of crops ’ ' by improved farming methods, the ambunt of increase possible is limited by the plant. Yielding ability is inherited, and many varieties selected when fertility. and management were not as good as they are now, are unable to make full use of the better conditions.

Consequently, in any scheme for crop improvement in Canterbury we must look first at our crop varieties.

The work on wheat at Lincoln is a good example of the value of producing varieties to suit the farming conditions under which they are to be grown. In the 1930’5, when the header harvester was replacing the binder, with a great saving of labour,, the Wheat Research Institute was able to release Cross 7, a high-quality, lodging-resistant, non-shattering wheat suitable for direct heading. It rapidly became the predominant variety on the

moderately fertile country in Canterbury. Over the last 20 years, the general level of fertility of the soils of Canterbury has risen under pastoral farming, and it would appear that Cross 7, when autumn sown, is not able to make full use of the improved fertility. The new variety, Aotea, released by the Crop Research Division, is able to take advantage of a higher level of fertility than Cross 7 and promises to yield about 20 per cent. more.

Our present techniques of management for maximum crop production are naturally based upon the behaviour of our standard varieties. New methods may give disappointing results because the old varieties are not sufficiently adaptable.

f that by further breeding, and by j selection at various fertility levels, 1 we can produce varieties that can - use more nitrogen to give still r greater yields. 2 Yield is, of course, only one - facet of crop production. Disease resistance, ease of harvesting; and

A new variety such as Aotea can open up the field for new cultural treatments for there is always the chance that it will respond to methods which had little effect upon the old varieties. For instance, nitrogenous fertilisers have had little effect upon the yield of Cross 7. On the other hand, some trials by the Extension Division of the Department of Agriculture have shown that Aotea can give an economic response to high rates of these fertilisers. It is possible

quality are also important. For instance, Cross 7 set new standards for milling and baking quality and for suitability for heading. Hilgendorf set an even higher standard for baking quality, and Aotea and. Arawa have a better resistance to many diseases than do Cross 7 and Hilgendorf.

A new growth chamber at Lincoln, in which four successive crops of wheat can be grown in less than a year, is accelerating the work of breeding disease-

resistant strains of our wheat varieties. The same process of crop improvement is being followed, in other crops. For instance, in Canterbury, rape is often wiped out by aphids or “blight," especially in dry seasons when the feed is most needed. An aphid-resistant variety has been bred at Lincoln and should be available to farmers in about three years’ time. The, new swede variety, Calder, is resistant to aphids and turnip mosaic, and progress is being made in selecting turnip and swede varieties for resistance io clubroot and dry-rot. The mosaic disease of turnips which recently has been very destructive, is being investigated in the hope that the breeding of resistant varieties may be possible. Although most potato varieties are able to give high yields under good conditions, they are normally severely limited by disease, soil conditions and climate. Conse-

quently, as well as breeding for yielding ability, we are endeavouring to introduce disease and drought resistance Into our new varieties so that yields will be more even and not subject to seasonal fluctuations. The role of crop Improvement as visualised at the Crop Research Division is to Introduce or breed new crop varieties which will be more suited to improved farming conditions than our old varieties, and to give a lead to the farmer by better rotations and cultural practices which will enable high production to be maintained over long periods. We aim to provide under certification, varieties with higher yield capacity, disease resistance, drought resistance, and quality. As each variety nears the limit of its capacity with the better farming systems, more new varieties will be released, so that production will not be limited by the failure of a variety to jive a higher yield under better farming.