EFFECTS OF NITROGEN APPLICATION ON BIOMASS ACCUMULATION, REMOBILIZATION, AND SOIL WATER CONTENTS IN A RAINFED WHEAT FIELD
Wenxue Duan, Zhenwen Yu, Yongli Zhang, Dong Wang, Yu Shi, Zhenzhu Xu
Abstract
This study examined the effects of different levels of N fertilization on dry matter accumulation and remobilization, and soil water contents in a rainfed winter wheat field. The experiments were carried out during growth seasons in 2009 – 2012 in a hilly region in Shandong Province, China. The N rates applied were 0 (N0, the control), 90 (N1), 120 (N2), 150 (N3), 180 (N4), and 210 (N5) kg N ha 1 . Our results showed that N fertilization significantly increased dry matter accumulation and post-anthesis assimilates compared with controls. At anthesis, total above-ground biomass increased significantly with increasing N rate up to 150 kg ha 1 and then leveled off in the 2009 – 2010 and 2011 – 2012 growth seasons. However, the biomass in the 2010 – 2011 growth season did not vary with different N rates. At maturity, the accumulation of dry matter in vegetative organs significantly increased with increasing N rate up to 150 kg ha 1 and then leveled off in all growth seasons. Of all the treatments, N3 and N4 had relatively higher total above-ground biomass at maturity. In contrast, dry matter remobilization efficiency showed a declining trend under increasing N rate. The higher post-anthesis assimilates and the contribution of pre-anthesis assimilates to grains were obtained at N rates of 150 and 180 kg ha 1 in all growth seasons. Soil water contents in 0 – 120, 0 – 100, and 40 – 160 cm soil layers during each growth season decreased significantly with increasing N rate up to 150 kg ha 1 . The maximum grain yields were obtained under N rate of 150 kg ha 1 in all growth seasons, with the highest grain yield being 7160.8 kg ha 1 in the 2011 – 2012 growth season. Our results suggested that N fertilization at 150 kg N ha 1 was optimal for grain production via promoting above-ground biomass and soil water consumption in deep soil layers. These results should help provide guidance for N fertilization management for optimal and sustainable wheat production in the said region.
Effects of Different Water Stress Levels on Biomass Yield and Agronomic Traits of Switchgrass (Panicum virgatum L.) Varieties under Semi-Arid Conditio
Erdal GONULAL, Suleyman SOYLU, Mehmet SAHIN