Submitted to: Journal of Cereal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 20, 2002
Publication Date: January 20, 2003
Citation: ALTENBACH, S.B., DUPONT, F.M., KOTHARI, K.M., CHAN, R., JOHNSON, E.L., LIEU, D. TEMPERATURE, WATER AND FERTILIZER INFLUENCE THE TIMING OF KEY EVENTS DURING GRAIN DEVELOPMENT IN A US SPRING WHEAT. JOURNAL OF CEREAL SCIENCE. 2003. 37(1)p. 9-20. Interpretive Summary: When wheat is grown at different locations, variations in grain yield and quality result that are due largely to differences in environmental conditions. We have studied effects of temperature, water and fertilizer on the growth of the plant and the developing grain in a US wheat variety. Wheat plants were grown in greenhouses under carefully controlled conditions. During the period of grain development, plants were subjected to either moderate (24oC) or high (37oC) daytime temperatures or a combination of high (37oC) daytime and high (28oC) nighttime temperatures. Plants were either well-watered or subjected to drought and either supplied with ample fertilizer or deprived of fertilizer after flowering. The effects of environmental variables on the appearance of the plants and the timing of key events in kernel development were assessed. The accumulation of protein and starch, the reserve materials that provide economic value, was also evaluated under the different environmental conditions.
Technical Abstract: Controlled environments were used to define the manner in which temperature, water and fertilizer affect the timing of key transition points during grain development and to investigate the effects of combined environmental factors in a US spring wheat (Triticum aestivum (L.). When plants were subjected to very high temperature regimens (37/17oC or 37/28oC day/night) during grain development, the times to maximum kernel water content, maximum dry weight and harvest maturity were shorter than in plants maintained under a 24/17oC day/night regimen. Starch accumulated at similar rates, but the onset and cessation of starch accumulation occurred earlier. Apoptosis in endosperm tissue also occurred earlier under high temperatures and coincided with physiological maturity. The addition of drought to the 37/17oC regimen further shortened the time to maximum water content and dry weight and reduced the duration of starch accumulation, but did not influence the timing of protein accumulation or kernel desiccation. Post-anthesis fertilizer had little effect on time to maximum water content, dry weight, apoptosis, or harvest maturity under any of the temperature regimens and did not influence the timing of starch accumulation. However, both the rate and duration of protein accumulation were reduced when post-anthesis fertilizer was omitted.