Abnormal seedling growth of wheat cultivar Rongotea : A dissertation submitted in partial fulfilment of the requirements for the Diploma of Agricultural Science in the University of Canterbury

Abstract

Wheat (Triticum aestivum L.) cultivar Rongotea has been released in 1979. It was derived from the cross of Raven with 66RN430, a Mexican semi-dwarf line, made in 1966. It is a medium short-strawed wheat, taller than Karamu but shorter than Kopera. It has dark green foliage, a fully awned ear, white chaff, and large-sized red coloured semi-hard grain, some sprouting resistance, and good resistance to shattering. Rongotea also has some resistance to Septoria leaf blotch when autumn sown in Canterbury. Milling quality of the grain is similar to that of Aotea on the Wheat Research Institute's Buhler mill, and baking quality of the flour is markedly superior to that of Karamu, and at least equal to Kopara and Aotea. It is well adapted to all spring wheat areas of the country and should be a satisfactory replacement for Karamu, particularly as a winter sown crop in Canterbury. It could also be an alternative to Kopara in the Canterbury region for autumn sowing, as it is only two or three days earlier than Kopera in ear emergence (McEwen and Hadfield, 1978). It has been observed that there is a particular Rongotea seed line that produces some degree of abnormality at the seedling stage. Some characteristics of abnormality found on other wheat cultivars (Chernyl, 1969) were: a) the first leaf emerging from the coleoptile was spirally twisted; b) coleoptiles split with twisted leaves emerging from them; c) after emerging from the coleoptile some of the first leaves split and d) the first leaves were unable to push up through the tips of the coleoptiles thus becoming crumpled. The project was, therefore, conceived to study the effects of abnormality in the growth of the seedlings and to find the possible causes and solutions to the abnormality of this particular wheat cultivar.