Growth and productivity of maize under nitrogen stress
1997
Below, F.E.
While it is well established that nitrogen (N) supply affects the reproductive development and yield of maize, the mechanisms involved are not fully understood. This presentation will summarize some of my laboratory's recent research on the role of N in maize productivity. Data obtained under controlled conditions using in vitro culture will be presented along with results of field trials to assess the impact of N supply on reproductive development. Except at the lowest levels of N supply, yield increases from N fertilizer additions in the field were mostly the result of more filled kernels due to less kernel abortion. Decreased N accumulation after flowering appeared to be most closely associated with N-induced kernel abortion. In general, N deficiency decreased the proportion of N partitioned to stalks and leaf sheaths, increased the proportion in reproductive fractions, and accelerated N remobilization from the leaves. Omission of N from the culture media of in vitro grown kernels markedly decreased endosperm dry weight, even though high levels of sugars were available. The effect of N availability was greatest during the period (first 12 days) of endosperm cell division. Subsequent decreases were attributed to lower activities of starch synthesis enzymes. These data show that N supply plays important roles in maximizing kernel initiation and set, and in the establishment and filling of the kernel sink.
Показать больше [+] Меньше [-]