Maize population improvement for low soil N: Selection gains and the identification of secondary traits
1997
Lafitte, H.R. | Banziger, M.
Tropical maize is frequently grown under slab-optimal levels of soil N. Cultivars with improved tolerance to low N can be developed by simultaneously selecting for greater grain yield under stress and for secondary traits expected to confer an advantage under stress. Several traits were combined for ideotype selection in the tropical maize population Across 8328 BN. Gains over five cycles of full-sib recurrent selection averaged 84 kg grain/ha/year (4.5 Per cent per year) at low N and 120 kg grain/ha/year (2.3 Per cent per year) at high N. Selection under low N using this ideotype was associated with increased vegetative biomass, increased movement of N from vegetative parts to the grain, delayed senescence, decreased floret number, and an increase in the length of the lag phase of grain growth. Another approach to improving yield under low N is the use of controlled drought as a surrogate stress. Four tropical maize populations were selected for tolerance to drought at flowering and during grain filling. Gains over two to eight selection cycles averaged 100 kg grain/ha/year (3.4 Per cent per year) at low N and 75 kg grain/ha/year (1.2 Per cent per year) at high N. Two possible mechanistic explanations for improved performance under low N of populations selected for drought tolerance are reduced ear abortion and delayed leaf senescence.
اظهر المزيد [+] اقل [-]الكلمات المفتاحية الخاصة بالمكنز الزراعي (أجروفوك)
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