Post-silking accumulation and partitioning of dry matter, nitrogen, phosphorus and potassium in maize varieties differing in leaf longevity

Abstract

Maize grains are formed after silking, but not all dry matter (DM), nitrogen (N), phosphorus (P) and potassium (K) deposited in grains are accumulated during grain filling. There is a conflict between sustaining post-silking photosynthesis and the remobilization and recycling of N, P and K from leaves to grain. To study the accumulation and partitioning patterns of DM, N, P and K after silking in maize with different leaf longevity, two field experiments with six maize varieties including early-senescing (old varieties) and stay-green leaves (new varieties) were conducted in successive years. The results demonstrated that new varieties had larger total leaf area and longer green leaf duration, and took up more N, P and K after silking than old varieties. Post-silking leaf appeared to provide sufficient assimilates for grain formation, while large amounts of N, P and K accumulated pre-silking were remobilized and exported from vegetative tissues, especially from leaves, in all varieties during grain filling. Post-silking leaf N export caused a large decrease in leaf N concentration in all maize varieties. Post-silking uptake of N and P account for 11–43% and 16–55% to total content of whole plants at maturity, but a post-silking loss of K from maize plants was observed, especially in old varieties. The export of N, P and K from leaves was similar in all varieties and an un-synchronized accumulation and partitioning of N, P and K during plant development was observed.