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Nitrogen Uptake and Partitioning in Stay‐Green and Leafy Maize Hybrids
Author(s) -
Subedi K. D.,
Ma B. L.
Publication year - 2005
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci2005.0740
Subject(s) - biology , hybrid , leafy , dry matter , agronomy , nitrogen , horticulture , botany , chemistry , organic chemistry
Nitrogen requirement, uptake, and remobilization patterns have been extensively studied for normal maize ( Zea mays L.), but there is limited published work for the stay‐green (SG) and Leafy hybrids. Under controlled greenhouse conditions, growth, N uptake and partitioning patterns of three contrasting maize hybrids (a conventional, ‘Pioneer 3905’, one bearing the SG trait ‘Pioneer 39F06 Bt’, and one with Leafy trait ‘Maizex LF850‐RR’) were investigated. Individual plants grown in 6‐L plastic pots were subjected to five different N fertilization regimes: (i) no N supply from seeding to V8, (ii) withholding N supply after V8, (iii) withholding N supply after silking, (iv) withholding N supply from 3 wk after silking to physiological maturity, and (v) continuous N supply from emergence to physiological maturity (control). Leaf chlorophyll content, dry matter, N uptake, and accumulation in different plant parts were measured. The Leafy hybrid had a greater number of leaves and total plant dry matter while kernel yield was similar to that of the other two hybrids. There were no differences in total N uptake and partitioning among the hybrids studied across all five N treatments. The SG hybrid (Pioneer 39F06 Bt) remained green until physiological maturity only when there was a continuous N supply in the growing medium. For all hybrids, N supply was more critical before silking than after silking as limiting N supply reduced ear size, kernel yield and N uptake. Restriction of N supply from seeding to V8 caused an irreparable reduction in ear size and kernel yield (30%). Withholding N supply fromV8 to maturity reduced kernel yield by 22% and N uptake by 53%. There was no yield reduction when N was restricted from silking, or 3 wk after silking to physiological maturity. The results indicate that stay‐greenness in maize was exhibited only when there is an adequate supply of N in the growing medium and is not associated with greater N acquisition or remobilization than the conventional hybrids even with full N fertilization.