| ?Objective?Drought and water shortage is one of the main limiting factors for cotton production in Xinjiang.The root system is the main organ for water absorption of plants,and the relationship between the biological characteristics of roots and water use efficiency is determined.The cotton has its own strong drought-resistance ability,and taps its biological water-saving potential.The high-yield and stable production under the premise of high-yield and stable production is the sustainable cotton in Xinjiang.The key to development.?Methods?In this experiment,different drought-tolerant cotton varieties?min-type Xinluzao 17,L17 and drought-resistant Xinluzao 22,L22?were used as test materials,and three water treatments were set under the tube-planting conditions.For conventional irrigation(CK,irrigation amount is 4500 m3·hm-2),mild drought stress?W1,irrigation amount is 60%of CK?and moderate drought stress?W2,irrigation amount is20%of CK?.The system was used to determine the root morphology?root length,root diameter,root weight,root volume?,physiological Malondialdehyde,antioxidant enzyme activity,root activity)and structure?catheter diameter,number?and other indicators during the critical period of cotton.The relationship between the biological characteristics of roots and the accumulation and distribution of biomass in drought stress on drought stress,the relationship between root biological characteristics and water use efficiency was discussed.1.The root morphology and distribution of different drought-tolerant cotton varieties had different responses to drought stress.Compared with CK,the root weight density?RWD?,root volume density?RVD?and root length density?RLD?of 0-20 cm soil layer decreased under drought stress,and the decrease of L22 was 10.29%lower than that of L17.In the 120 cm soil layer,L22 increased with the increase of drought stress,while L17 showed the opposite trend.Compared with CK,the average diameter of L22roots increased significantly by 19.99%under drought stress,L17 increased by 5.86%during the Shengling period,and 4.32%decreased during the W2 condition.Among the varieties,the distribution ratio of L22roots in 40-80 cm soil layer was 43.95%,which was 18.08%higher than that of L17,but the distribution ratio of R17 and effective root length in 80-120 cm soil layer was significantly higher than L22.2.The physiological activities of roots of different drought-tolerant cotton varieties had different responses under drought stress.Under drought stress,root activity?RV?decreased,malondialdehyde?MDA?content increased,catalase?CAT?and peroxidase?POD?increased under W1 conditions,and varied under W2conditions.Among the varieties,L22 soluble protein?SP?content and RV were 17.67%and 23.78%higher than L17 in 0-40 cm and 80-120 cm soil layers,respectively.Under drought stress,the MDA increase of L17 was 1.33%higher than that of L22.The activity of superoxide dismutase?SOD?was 4.59%lower than that of L17 in the flowering stage,60.39%higher than that of L17 in the Shengling to the boll opening stage.The CAT of L22 was in W1 and W2.Under the condition,the increase was 9.05%and 20.30%higher than that of L17.Compared with W1 treatment,the POD of L17 decreased by 19.14%and L22increased by 2.57%under W2 condition.There was no significant difference in the decrease of RV between the two varieties under W1 conditions.Under the W2 condition,the decrease of L22 RV was 26.17%lower than that of L17.3.The number of cork layers,the number of rhizome conduits and the diameter of the catheter decreased under drought stress,but there was no significant difference between W1 and W2 treatment.Among the varieties,the number of L22 cork,the number of rhizome catheters and the diameter of the catheter increased by 33.33%,23.68%and 7.81%,respectively;the thickness of L17 cortex was significantly higher than that of L22,which was 12.62%.4.Drought stress significantly reduced the dry matter of the above two parts.L17 and L22 decreased by34.76%and 31.03%,25.51%and 52.12%,respectively,under W1 and W2 conditions.Among the varieties,the total dry matter in the upper part of L22 was 31.94%higher than that of L17.The proportion of dry matter to different organs varies depending on the variety and the period of growth.During the period of full bloom and full boll,the distribution ratio of dry matter to reproductive organs was significantly higher than that of L22.During the boll opening period,the distribution ratio of L22 dry matter to reproductive organs was 4.94%higher than that of L17.5.The water consumption and water use efficiency of different treatments vary from species to species.Under the same water condition,the total water consumption of L22 is 6.30%lower than that of L17.Drought stress reduced the total water consumption of the two varieties and improved the water use efficiency?WUE?.The water consumption reduction of L22 was 24.36%and 30.64%higher than that of L17 under W1 and W2 conditions respectively.The increase of WUE of L22 under W1 condition was higher than that of L17.It is 3.83%lower and 19.01%higher than L17 under W2 conditions.?Conclusion?The drought caused the root density of 0-20 cm soil and the root volume density of 0-80cm soil layer decreased,the content of CAT,POD and SOD increased,the content of MDA increased,the number of rhizome and the diameter of the catheter decreased,and the ratio of root to shoot increased.Finally,the above-ground vegetative organs,reproductive organs and total biomass are reduced.Compared with the drought-tolerant variety Xinluzao 17,the drought-tolerant variety Xinluzao 22 has a more uniform root distribution in the 0-120 cm soil layer,and remains higher in the 0-40 cm and 80-120 cm soil layers.The root activity and the higher diameter and number of rhizomes,especially under drought conditions,the roots become thicker,the density increases,and maintain higher RV,CAT,POD,SOD activity,thus ensuring lower soil during the growth period.Water consumption and high water use efficiency,Promoting shoot growth is a physiological mechanism with more drought tolerance and higher yield. |
PDF Full Text Request