Olugbemi, L. B.2011-11-022011-11-021968https://hdl.handle.net/10182/3992All plant activities take place within certain well defined conditions. For normal plant growth, certain environmental conditions such as temperature, light, moisture and mineral nutrients must be met. These requirements must be present at least in minimum quantities before manifestations of growth can be sustained. When the requirements are present at optimal levels, growth activities proceed at their highest rates, slowing down again as these optima are surpassed. For instance, when optimum temperature is exceeded, plant growth is slowed down and when maximum temperature is reached plant growth may either cease or the plant dies, depending upon the duration of the stress. The same is true of minimum temperature. The effects of temperature on plant growth do not only vary from one plant to the other or in different parts of a plant but also with stage of development. It is generally believed that plants are most sensitive to any given stress at their most active stages of growth. While much literature has accumulated on the effects of cold stress on plant tissues and on the screening of various varieties of crops for frost resistance, only little attention has been paid to the injurious effects of temperature stress on cereals. Almost nothing has been published in New Zealand in this field, even though late spring frost damage to wheat has been a regular occurrence over the last two to three decades. While it is true that reference has been made to the depressing effect of frost on yield of wheat, some of this information has been based on field observations where other stresses notably drought, might have interacted with temperature. It was deemed necessary, therefore, to investigate the effect of cold and heat stresses on at least one of the varieties of New Zealand wheat with the objective of determining the effect of temperature stress on (a) plant growth, (b) reproductive development and consequently grain yield per shoot, (c) the enzymatic activities of the developing grains and (d) the stage (or stages) of development at which the effects were most marked. In order to obtain adequate replication, this investigation was limited to one variety, Hilgendorf ‘61. This variety was chosen because it is one of the most widely grown wheats in the South Island, New Zealand, second only to Aotea and because owing to its early maturity it is most adversely affected by frost (Copp, pers. comm.).126 pagesenhttps://researcharchive.lincoln.ac.nz/pages/rightswheatgrain yieldplant growthenvironmental conditionstemperature stressgrain developmentplant physiologyfrost resistenceThesisDigital thesis can be viewed by current staff and students of Lincoln University only. If you are the author of this item, please contact us if you wish to discuss making the full text publicly available.ANZSRC::070305 Crop and Pasture Improvement (Selection and Breeding)ANZSRC::070302 AgronomyANZSRC::070303 Crop and Pasture Biochemistry and PhysiologyQ112836347