Department of Agronomy, NWFP Agricultural University, Peshawar, Pakistan.
J Sci Food Agric. 2010 Jan 15;90(1):21-9. doi: 10.1002/jsfa.3769.
Efficient use of nitrogen (N) is considered one of the most important inputs needed for increasing grain quality and crop productivity. Hypothesis was that grain quality and yield of maize (Zeamays L.) in north-west Pakistan are enhanced by increasing the rate of N, and that response to applied N is greater with an increase in the number of N split applications at high plant density compared to low density.
Field experiments were carried out on maize (cv. Azam) in summer 2002 and 2003 consisting of two planting densities and three N rates as main plots, and six split N applications as sub-plots. Year 1 had higher shelling percentage and stover yield (SY). Harvest index (HI) decreased but SY increased with increase in plant density. Increase in N rate and number of split N applications increased grain weight and protein content, HI and SY.
The highest N rate in four to five split applications increased maize grain quality and yield at both densities. Maize response to the interactive effect of year x plant density, year x N rate, and year x N timing suggests zonal specific effective N management practices for sustainable maize production in different agro-ecological zones.
高效利用氮（N）被认为是提高粮食质量和作物产量的最重要投入之一。假设在巴基斯坦西北部，通过增加氮的施用量，可以提高玉米（Zeamays L.）的籽粒品质和产量，并且与低密度相比，随着施氮次数的增加，高种植密度下对施氮的反应更大。
2002 年和 2003 年夏季在玉米（品种 Azam）上进行了田间试验，包括两个种植密度和三个氮水平作为主区，以及六个氮分施作为副区。第 1 年的脱壳率和秸秆产量（SY）较高。随着种植密度的增加，收获指数（HI）降低，但 SY 增加。增加氮水平和氮分施次数增加了籽粒重量和蛋白质含量、HI 和 SY。
在两个密度下，四到五次分施最高氮水平提高了玉米的籽粒品质和产量。玉米对年 x 种植密度、年 x 氮水平和年 x 氮时间的互作效应的反应表明，在不同的农业生态区需要特定区域的有效氮管理实践，以实现可持续的玉米生产。
