The Effects of Water and Salt Stresses on Growth of Seedlings of Cotton Variety Zhongmian 619

Abstract

【Background】 Cotton production in southern Xinjiang had heavily relied on plastic-film mulching due to its freshwater scarcity, but its long-term application has resulted in soil deterioration, reducing cotton yield and quality. How to alleviate these detrimental impacts of plastic-film mulching has become an urgent issue in sustaining cotton production in southern Xinjiang. The newly bred Zhongmian 619 has proven promising as it is early-mature and does not need mulching. Not mulching, however, increases soil evaporation and salt accumulation, thereby suppressing seed germination and its subsequent growth. 【Objective】 The purpose of this paper is to investigate how water and salt stresses due to removal of the mulch combine to affect the growth of Zhongmian 619 during its seedling stage, in attempts to find a suitable irrigation scheduling for it. 【Method】 The experiment was carried out in an artificial climate room, comprising three water treatments: 100% (I1), 80% (I2) and 60% of evapotranspiration (ET), and three salt stresses which were created by irrigating saline water with concentration 50 mmol/L(T1), 100 mmol/L(T2) and 150 mmol/L(T3) respectively. Irrigation at 100% of ET with freshwater was taken as control (CK). In each treatment, we measured the changes in height, leaf area, root biomass, chlorophyll content (SPAD), photosynthetic parameters and chlorophyll fluorescence of the cotton seedlings. 【Result】 When irrigation amount was the same, increasing salt stress suppressed plant elongation and leaf growth; it also reduced SPAD, and fresh and dry root weights. When salt stress was the same, all above traits increased with irrigation amount first, followed by a decline when the irrigation amount exceeded a threshold. Compared with CK, I2+T1 treatment increased plant height, leaf area, SPAD, fresh and dry root weights by 33.74%, 29.79%, 18.96%, 128.70% and 28.20%, respectively; its photosynthetic and chlorophyll fluorescence parameters were the best among all treatments. 【Conclusion】 Irrigating 80% of the evapotranspiration with saline water at 50 mmol/L concentration is the most suitable irrigation scheduling for Zhongmian 619 seedlings in southern Xinjiang of China.

Keywords

• water and salt stress
• early-mature cotton
• zhongmian 619
• cotton seedling
• photosynthesis
• chlorophyll fluorescence