Chin J Plant Ecol ›› 2009, Vol. 33 ›› Issue (2): 405-413.DOI: 10.3773/j.issn.1005-264x.2009.02.019

• Research Articles • Previous Articles     Next Articles

EFFECTS OF NITROGEN ON COTTON ROOT GROWTH UNDER DROUGHT STRESS AND AFTER WATERING DURING FLOWERING AND BOLL-FORMING STAGES

LIU Rui-Xian, CHEN Bing-Lin, WANG You-Hua, GUO Wen-Qi, ZHOU Zhi-Guo()   

  1. Laboratory of Crop Growth Regulation, Ministry of Agriculture, Nanjing Agricultural University, Nanjing 210095, China
  • Received:2008-01-11 Accepted:2008-08-13 Online:2009-01-11 Published:2009-03-31
  • Contact: ZHOU Zhi-Guo

Abstract:

Aim Our objective was to study effects of nitrogen on drought resistance in terms of changes in root development and activity of water-stressed cotton plants.

Methods We studied short-term water stress using pot experiments by withholding water for eight days and then watering for ten days at Nanjing Agricultural University in 2005 and 2006. Cotton plants were grown at three nitrogen levels (0, 240 and 480 kg N·hm-2).

Important findings Soil relative water content decreased with increasing N supply during the soil water stress period, while dry matter production and N accumulation increased. The root/shoot ratio and root-N/ shoot-N ratio increased with water stress and were smallest at 240 kg N·hm-2. Application of N increased the activities of peroxidase (POD) and catalase (CAT) of roots, but decreased superoxide dismutase (SOD) activity during water stress as well as during recovery. Malondialdehyde (MDA) content significantly (p<0.05) increased and was smallest in the 240 kg N·hm-2 treatment during water stress. On the 10th day after soil watering, MDA content at 240 kg N·hm-2was similar to that at 480 kg N·hm-2, but was less than that at 0 kg N·hm-2. Root vigor, which was adversely affected by water stress, was highest at 240kg N·hm-2. After soil watering, N application promoted root vigor. Trends of net photosynthetic rate were the same as those of root vigor during water stress. These results suggest that appropriate N supply (240 kg N·hm-2 in this investigation) may contribute to drought resistance of cotton plants by adjusting the antioxidant enzyme activities of roots, decreasing lipid peroxidation and boosting root vigor during water stress; however, excessive N supply (480 kg N·hm-2) had a deleterious effect on plant drought resistance.

Key words: Key words nitrogen, cotton, soil drought, re-watering, roots growth