| The conflict between winter wheat production and water scarcity in the Haihe Plain has become a growing issue.It is critical to optimize the irrigation system while balancing crop yield improvement and water usage efficiency with limited water resources.Based on previous researches,in this study we built a sufficient winter wheat population with strong individual before winter and improved drought resistance through sufficient moisture sowing and optical the sowing date and sowing rate.The study was conducted in Shenzhou experimental station of Drought Agricultural Experiment Station of Hebei Academy of Agriculture and Forestry Sciences and Hebei Xinji experimental station of China’s special scientific and technological innovation for grain yield and efficiency in the wheat season from 2018 to 2020.The study was conducted with two types of winter wheat varieties,two sowing date and six irrigation treatments.The two types of winter wheat varieties studied were drought-tolerant group(Shinong 086,Jimai 585,and Shixin 828)and drought-sensitive group(Shimai 22,Hengguan 35 and Jimai 418).Two sowing dates including suitable sowing date and later sowing date(W)were stuied.The six irrigation treaments were 1)control treatment(CKⅡ),wheat was irrigated at the 3-leaf stage and at the anthesis stage;2)wheat was irrigated at the 3-leaf stage(L3);3)wheat was irrigated at the 4-leaf stage(L4);4)wheat was irrigated at the 5-leaf stage(L5);5)wheat was irrigated at the 6-leaf stage(L6);6)No irrigation treatment in spring(CK0).The optimal irrigation period of single irrigation in spring was determined by analyzing the water consumption,yield composition,and morphological characteristics of winter wheat cultivars under various treatments,and the molecular physiological mechanisms of winter wheat in response to drought stress and rehydration under water-limited irrigation were further determined.The major results are as follows:1.Upon water-limited irrigation in spring,0-60 cm soil layer served as the primary water supply layer for wheat growth,and changes in water content(swc60)in this layer had a significantimpact on wheat growth and yield formation.With single irrigation in spring,the best irrigation period for winter wheat was at the 4-leaf stage.The average irrigation volume in L4 treatment was reduced by 62.7 mm when compared to the CKⅡtreatment.Drought stress was low prior to irrigation,and the swc60 was less than 60%until the end of milk maturity period after irrigation.Although the soil drought stress was low during the late filling stage for L5 and L6 treaments,soil drought stress was intensified before irrigation,which had a significnat negative impact on crop growth and development.On the contrary,soil drought stress for L3 treatment was too severe in the later stage,which slowed filling speed and resulted in a significant decrease in grain weight and yield.Along with delating the single irrigation in the spring,total soil water consumption was decreased,the proportion of irrigation consumption was increased,and the proportion of soil water storage consumption was decreased.If water consumption from jointing stage to flowering stage was decreased,tleading to water consumption in flowering and maturity stages increased significantly.2.Under water limited irrigation in spring,the yield of winter wheat decreased significantly,and yield loss of drought-tolerant group was lower than that of drought-sensitive group.For the overall performance of single irrigation treatment with different leaf ages in spring,the lowest yeild loss was irrigation treatment at 4-leaf stage in spring,with an average reduction of about 11.2%,whereas the irrigation yield of spring 3,5 and 6 leaf stage treatments decreased by 17.1～38.0%.Compared with the suitable sowing treatment,the average yield of WCKⅡ treatment with late sowing was lower than that of CKⅡ treatment,but there was no significant difference on yield of single irrigation treatment in spring and corresponding suitable sowing treatment.While,the yield,WUE,and IPE of spring 4 leaf age irrigation treatment(L4 and wl4)were significantly higher than those of other spring single irrigation treatments.With the delay of irrigation in spring,the kernel number gradually decreased and the 1000 grain weight gradually increased.The spike number of irrigation treatment at 4-leaf stage in spring was the highest,which was 16.5%higher than that of other one-time irrigation treatments in spring.The three yield composition were more balanced and coordinated.3.Under water limited irrigation in spring,with the delay of the first irrigation in spring,the spike differentiation process of winter wheat was accelerated after floret differentiation.the degree and duration of soil drought stress were increased significantly,which has shortened the time of floret primordium differentiation to anther tetrad stage,increased the number of floret degradation,reduced the kernel number,the plant height,top 3 leaf area,and leaf area index(LAI)of winter wheat.Decreases of plant height and leaf area in drought-tolerant variety Hengguan35 were lower than those in drought-sensitive variety Shinong086.LAI was decreased slightly at 3 and 4 leaf age irrigation treatments in spring,and dramatically reduced when irrigation was delayed to 5 and 6 leaf age.Early irrigation(spring 3 leaf age)accelerated the senescence process of flag leaves from 15 to 30 days after anthesis of winter wheat,whereas late irrigation(spring 6 leaf age)resulted in lowered photosynthetic rate and transpiration rate of flag leaves after anthesis of winter wheat.Irrigations at spring 4 and 5 leaf age were conducive to maintain higher photosynthetic rate and transpiration rate after anthesis of flag leaves.In addition,water limited irrigation led to the advance of a rapid increase period of grain filling and decrease of grain filling rate in winter wheat plants,which was more obvious in Shinong086.With the delay of single irrigation time in spring,the effective filling period was prolonged,the peak filling rate and fitting 1000-grain weight increased,which improved the contribution ratio of dry matter assimilates to grains after anthesis.However,the transport amount of dry matter to grains after anthesis decreased significantly,resulted in the reduction of the total amount of dry matter transported to seeds during anthesis.4.Under water-limited irrigation in spring,drought stress rehydration activated the damage of reactive oxygen species and osmotic stress to wheat growth and development,significantly reduced the antioxidant level and hormone content in plants,and alleviated the pressure of cell osmotic stress.After rehydration at 3 and 4 leaf ages in spring,winter wheat had strong ability to restore oxidative balance,osmotic tolerance,and hormone regulation.Delaying irrigation to 5 and 6 leaf age in spring lengthened dry period,increased the severity of the stress,and hampered recovery..The drought-tolerant variety Hengguan35 showed less oxidative damage,reduced antioxidant enzyme activity,and increased accumulation of stress-related ABA,JA,and SA hormones,as well as decreased osmotic stress.The drought-sensitive variety Shinong086,on the other hand,showed a high sensitivity to rehydration conditions.5.At the same time,the expression of these genes was decreased after rehydration at 4 and 5 leaf ages in spring,indicating an important mechanism of winter wheat response given rehydration compensation.The expression profile of genes involved in redox homeostasis showed that the degree of activation or suppression of DEGs in spring 3 and 4 leaf age rehydration treatment was lower than that in spring 5 and 6 leaf age rehydration treatment.Abundance of IAA was increased after rehydration at different leaf ages;ABA,JA,and other hormones were decreased;L-tryptophan was decreased;serine,L-aspartic acid,and L-glutamate were increased in L3,L4 and L5 treatments,and reached summit in L4 treatment.In conclusion,sufficient winter wheat population was constructed through sufficient moisture sowing,sowing date the matched suitable sowing amount.Water-limited irrigation in spring was reduced from twice to single time.Spring 4 leaf age was the best irrigation period,with minimum yield loss and the highest WUE behavior.Spring 4 leaf age irrigation can better coordinate the drought stress before irrigation and the drought stress in the middle and late filling stage of winter wheat,better regulate the plant height,leaf area and total stem number,which is conducive to maintaining a high photosynthetic rate and transpiration rate after anthesis,and maintaining dry matter transport to grains after anthesis.The higher panicle number and 1000 grain weight compensate for the negative effect of panicle grain number reduction.This study clarified the functions and metabolic pathways of genes,proteins,and metabolites in response to drought stress rehydration,and systematically revealed that rehydration alleviated the peroxidation and osmotic stress caused by water deficit in both cultivars.To achieve a greater level of rehydration compensation and drought tolerance,HG35 used a more sensitive abscisic acid signal transduction and a balanced reactive oxygen species pathway than SN.Finally,we provided insights into the mechanism of water limited irrigation on the growth and yield formation of winter wheat in spring,as well as a foundation for deviloping a precise and efficient spring water-limited irrigation system of wheat. |
PDF Full Text Request