Modern cropping is based on relatively high plant density. The improved grain yield per unit area of modern maize (Zea mays L.) hybrids is due to the increased optimum plant population rather than the improved grain yield per plant. High plant density has been widely used to enhance grain yield in maize. Subsequently we review the effect of planting density on physiology, phenology, morphology, nitrogen use efficiency, water use efficiency grain yield information in maize crop. At higher plant populations reduced grain yield also results from the increased pollento-silking interval and the following barrenness. However, it may lead to higher risk lodging hence causing significant yield loss of the crop. Future insights are morphological and physiological basis controlling barren and stalk lodging resistance. How root traits, and anatomy of sheath and stem of maize plants correspond to high plant population and a further study on the physiological and biological basis of organ development that may govern the mechanisms of high plant density would be essential for future research.

Adjustment of sowing date and nitrogen (N) use help alleviate farmland contradiction under fluctuating climate in Jianghuai region of China. In this study, two wheat varieties were used to study the interactive effect between two sowing dates and two basal to topdressing ratios of N fertilizer, each treatment of eight combinations arranged in Randomized Complete Block Design (RCBD) with three replications was conducted in two consecutive growth seasons of bread wheat. As results of two years of investigation, wheat plants with an excessively delayed sowing date showed a significant reduction in flag leaf angle, flag leaf area, main stem spike length and photosynthesis rate, yet a increased basic seedling number and transpiration rate, which corresponded to a notable loss in thousand kernel weight and grain yield. An increase in the proportion of topdressed N led to an increase in flag leaf angle and leaf area index, and a lower spike number per unit and thousand kernel weight, to indicate a loss of grain yield. These findings suggest that excessively delayed sowing date and high N topdressing ratios severely affected the canopy structure and thousand kernel weight of bread wheat, and subsequently reduced grain yield. Based on membership function analysis, a sowing date of 25 October coupled with the N topdressing ratio of 7:3 (the basal to topdressing ratios of N fertilizer) was the ideal combination to optimize the wheat industry in Jianghuai region of China.

Drought is the most important factor limiting plant production in the majority of agricultural crops of the world. Wheat is generally grown on arid-agricultural fields. An experiment was conducted at the Plant physiology research area, Agronomic Research Institute Faisalabad, during winter 2010-11 to evaluate the effect of drought on wheat variety Lasani 2008. The experiment was comprised of following treatments. T 1 Normal moisture (3 IR at CRS, Booting and grain filling), T 2 No irrigation (only rainfed) control, T 3 water spray (100 ppm), T 4 ascorbic acid (100 ppm), T 5 salicylic acid (100 ppm), T 6 calcium chloride (100 ppm), T 7 glycinbetain (100 ppm). According to the resulting data the treatment in which three irrigation were applied produced more no. of tillers (52%), spikelet per spike (41%), spike length (30%), grain per spike (58%), grain yield (54%), biological yield (35%) as compared to control. The treatment in which no irrigation was applied produced less no. of tillers, spikelet per spike, spike length, grain per spike, grain yield, biological yield. Thousand grain weight and harvest index were non significant among all treatments.