干旱区水氮调控对棉花根、冠生长特性及产量的影响

摘要

Water and nitrogen ( N) are two important factors impacting crops growth, it is necessary to pay much attention to the synergistic regulation effects of water and nitrogen on crops in arid areas, especially in northwest China. To address the coupling effects of water&N interaction on yield and photosynthetic parameters of cotton, a field experiment was carried out to study the growth characteristics in terms of belowground ( root) and aboveground ( shoot) parts in cotton growing stages and the synergetic effects of water and N regulation on cotton yield components. In this study, three irrigation quotas (i. e. 3 300, 3 900 and 4 500 m3·hm-2) and four N rates (i. e. 150, 225, 300 and 375 kg·hm-2) were set up in a completely ran-domized block design with three replicates. Results showed that the treatment with water and nitrogen amounts at 3 900 m3 · hm-2 and 300 kg·hm-2 promoted photosynthetic parameters ( Pn, Tr) and SPAD value and leaf WUE of cotton leaf in differ-ent stages. Dry weight of cotton root showed a parabolic curve with nitrogen amounts increasing, while shoot parts increased gradually with nitrogen application amounts increasing. Dry weight of cotton root under different irrigation amounts reached the maximum in each growing stage at N 300 kg·hm-2 , but the root/shoot ratio of cotton present declined gradually, also the ra-tio decreased with irrigation amounts increased. Deficient irrigation ( W3 300 treatment) was benefit to increase the ratio of root to shoot, but it led to a significant decline in photosynthetic parameters ( Pn, Tr) and SPAD values and leaf WUE. In this experiment, it generated a pleasant cotton height at 79 cm and an improvement in numbers of available bolls and single boll weight when irrigation quota at 3 900 m3 ·hm-2 and N rate at 300 kg·hm-2 , available bolls increased 1. 0 and 0. 4 per plant, single boll weight increased 0. 16 and 0. 09 g, yield was increased by 8. 35% and 4. 62%, and the lint percentage was in-creased by 1. 4% and 0. 7%, compared with those of the treatments of W3 300 and W4 500 . Therefore, the suitable ratio of root to shoot of cotton was about 0. 111.%为了探明水分和氮素对棉花生长发育的影响,设置了3个灌溉水量和4个施氮量,研究了棉花生育时期地下(根)和地上部分(冠)的生长特性,揭示了水氮调控对棉花根、冠生长以及产量的影响效应。试验结果表明：不同生育时期,灌溉水量为3900 m3·hm-2、施氮量为300 kg·hm-2时能提高棉花叶片光合速率( Pn)、蒸腾速率( Tr)、叶绿素SPAD值和水分利用效率( WUE)。随着施氮量的增加,棉花根系干物质量呈先增加后降低而地上部分干物质量呈逐渐增加的趋势,在不同灌溉水量下,施氮量为300 kg·hm-2时棉花各生育期根系干物质量均达到最大,但棉花根冠比呈逐渐降低的趋势,且随着灌溉水量的增加棉花根冠比也呈降低趋势。水分亏缺( W3300处理)有利于棉花根冠比的增大,但显著降低了棉花光合参数( Pn、 Tr)、叶绿素SPAD值和WUE。在本试验条件下,当灌溉水量为3900 m3·hm-2、施氮量为300 kg·hm-2时棉花株高适宜(79 cm左右),有效铃数和单铃重较高,较W3300处理和W4500处理有效铃数分别增加1．0、0．4个·株-1,单铃重增加0．16、0．09 g,产量提高8．35%、4．62%,衣分增加1．4%、0．7%,棉花适宜的根冠比为0．111。