Response of Root-Canopy Index of Winter Wheat on Persist Drought
LIU Rong-hua, CHENG Lin, HU Cheng-da
2019, 40(11):
702-711.
doi:10.3969/j.issn.1000-6362.2019.11.004
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In order to clarify the response characteristics of winter wheat root and canopy index to drought sustainable development, two years of drought persist experiments in 2015/2016 and 2016/2017 after returning green stage of winter wheat were conducted, and the influence of soil moisture persistently reduction on leaf water content, root activity, stomatal conductance, etc. were studied. The results indicated that, under the condition of soil moisture reduced continuously, the water content in different organs of winter wheat decreased nonlinearly, and the decreasing rate was much more obviously after jointing, among them, the leaf sheath water content decreased the most by 41.9% on average. With drought duration, the difference of leaf gas exchange parameters between treatments of drought persistent and control was increased, the net photosynthetic rate decreased further with continuous drought, the stomatal conductance as well as transpiration rate of leaves increased differently at returning green stage, and turned decline continuously after jointing. The longer the drought lasted, the more obvious that non-stomatal limiting factors affecting photosynthesis. The continuous drought changed root distribution in deep soil. Root volume percentage in 60?80cm soil layer in drought treatment was significantly higher than that in the control group. Meanwhile, the physiological function of the root system was senescent prematurely, especially during jointing and booting stage, the root activity dropped sharply, and after booting stage, the root activity reduced more than 60% comparing with the control group. On the whole, the indices such as plant water content, leaf gas exchange parameters and root activity had generality and individuality response to persistent drought, the sensitive coefficient of root activity to soil moisture variation was highest, and the response speed of plant water content to soil moisture was lowest.