a1_Soil water deficit is a major limitation to agricultural productivity in arid regions. Leaf photosynthesis can quickly recover after rewatering and remains at a higher level for a longer period, thus increasing crop yield and water-use efficiency (WUE). We tested our hypothesis that leaf photosynthesis and root activity of water-stressed cotton (Gossypium hirsutum L.) plants could quickly recover after rewatering at a certain growth stage and it should not influence a cotton yield but increase WUE. Treatments in this study included two degrees of water stress: mild water stress (V1) and moderate water stress (V2) imposed at one of four cotton growth stages [i.e., S1 (from the full budding to early flowering stage), S2 (from early flowering to full flowering), S3 (from full flowering to full bolling), and S4 (from full bolling to boll-opening)]. The soil water content before and after the water stress was the same as that in the control treatment (CK, 70-75% of field capacity). Water deficit significantly reduced the leaf water potential, net photosynthetic rate, and stomatal conductance in cotton. The extent of the decline was greater in S2V2 treatment compared to others. Water deficit also reduced root activity, but the extent of inhibition varied in dependence on soil depth and duration. When plants were subjected to S1V1, the root activity in the 20-100 cm depth recovered rapidly and even exceeded CK one day after rewatering. An overcompensation response was observed for both photosynthesis and aboveground dry mass within one to three days after rewatering. Compared with the CK, S1V1 showed no significant effect on the yield but it increased total WUE and irrigation WUE., a2_These results suggest that even a short-term water stress during the S1, S2 and S4 stages mitigated, with respect to the root activity, the negative effect of drought and enhanced leaf photosynthesis compensatory effects of rewatering in order to increase cotton WUE with drip irrigation under mulch in arid areas., H. H. Luo, Y. L. Zhang, W. F. Zhang., and Obsahuje seznam literatury
The effects of moisture stress on leaf water potential ('ť|eaf)> photosynthetic rate (/^n) and stomatal resistance (r^) of cotton, Gossypium hirsutum L., were studied under field conditions. Sprinkler irrigation trials were conducted using the single source line technique. r^ increased and decreased as a result of moisture stress, more than in a concurrent drip irrigation experiment, r^ was only slightly affected by irradiance when the plants were subjected to moisture stress, but it decreased in response to an increase in irradiance (/) in the well irrigated plants. A linear relationship between T^ieaf and r^ and between 'ťigaf and found in both experiments at low /, whereas exponential relationship was found at high I. Even though high values of r^ were recorded under the extreme moisture stresses of both experiments, intemal CO2 concentration (cj) increased during the day, indicating that non-stomatal factors (such as mesophyll resistance) are the main factors limiting the photosynthetic process.