| Under the background of food security threat and water shortage,the problems of secondary salinization and agricultural production capacity improvement in Hetao Plain need to be solved urgently.Aiming at the problems of spring drought,returning saline-alkali weight and rigid constraint of water resources in saline-alkali land of Ningxia Yellow River irrigation area,a kind of maize salt suppression and yield increase tillage and water-saving irrigation technology is proposed,which has important theoretical and practical significance for agricultural production and ecological sustainable development in this area.Therefore,the split-plot design was used in this experiment The main treatments were silt ridge tillage and conventional rotary tillage.The sub-treatments were four irrigation quotas:local conventional irrigation(4500m3·hm-2),10%water reduction(4050m3·hm-2),20%water reduction(3600m3·hm-2),and 30%water reduction(3150m3·hm-2).The effects of different treatments on soil water and salt dynamics,maize production performance,photosynthetic physiology and water use characteristics were studied.The results are as follows:1.The soil moisture content gradually increased with the deepening of the soil layer.The silt ridge tillage effectively increased the soil moisture content of 0～40cm compared with the ordinary rotary tillage.At the seedling stage,the soil moisture content of 0～20cm and 20～40cm soil layers under the same irrigation quota was 9.8%,20.0%,6.0%,26.8%and 10.1%,7.4%,14.9%,9.2%higher than that of ordinary rotary tillage,respectively.The soil moisture content of 0～20cm soil layer was 49.2%,17.1%,25.2%,35.8%higher than that of ordinary rotary tillage.The total salt content of 0～60 cm soil was significantly reduced by ridge tillage,showing a certain salt suppression effect.In addition,the soil salinity increased with the decrease of irrigation quota,and the reduction of irrigation amount increased the effect of ’returning salt’.There was a significant correlation between soil compaction and tillage methods,and the effect of irrigation amount on soil compaction was not significant.The silt ridge tillage significantly reduced the compactness of the topsoil,improved the soil structure,and laid a good foundation for salt suppression and efficiency.2.Under the same irrigation amount,the water use efficiency and irrigation use efficiency of smash-ridging tillage were significantly higher than those of conventional rotary tillage.Under two different tillage conditions,the water use efficiency and irrigation use efficiency of TIW3(smash-ridging tillage,20%water reduction,irrigation quota of 3600m3·hm-2)and T2W3(conventional rotary tillage,20%water reduction,irrigation quota of 3600m3·hm-2)were the highest,indicating that when the water reduction was 20%,that is,the irrigation quota was 3600m3·hm-2,the production efficiency was the best,and the water could be saved by 20%in actual production.3.Under the condition of the same irrigation amount,the plant height,stem diameter,leaf area index,dry matter accumulation and yield of maize were increased.Under the condition of 20%water reduction,the yield of smash ridging tillage and ordinary rotary tillage decreased by 8.3%and 1.6%respectively compared with the control treatment,but the difference was not significant,indicating that 20%water could be saved without significantly affecting the yield,and water saving and efficiency improvement could be achieved.4.The transpiration rate(Tr),intercellular CO2 concentration(Ci),stomatal conductance(Gs)and net photosynthetic rate(Pn)of maize leaves under the treatment of powder ridge tillage and ordinary rotary tillage were inconsistent at different growth stages.Under the same irrigation amount,the powder ridge tillage effectively increased the photosynthetic intensity at the filling stage.Among them,stomatal conductance increased by 28.3%,34.7%,25.2%and 8.3%respectively compared with rotary tillage,intercellular CO2 concentration decreased by 9.2%,26.9%and 24.5%respectively compared with rotary tillage,and net photosynthetic rate increased by 12.4%,47.6%,34.9%and 68.8%respectively compared with rotary tillage.In addition,the photosynthetic intensity decreased with the decrease of irrigation amount.When the water reduction exceeded 20%,the photosynthetic intensity was significantly affected,which limited the growth and development of plants.5.Tillage methods have little effect on the physiological enzyme activity of maize leaves and irrigation quota.In contrast,powder ridge tillage effectively increases the stress resistance of maize plants.Reducing irrigation amount will significantly affect the physiological activity of maize.When the water reduction is 30%,the SOD,POD,CAT enzyme activity,MDA,Pro content and cell membrane permeability of leaves are significantly increased,and the relative chlorophyll content is reduced.It shows that when the water reduction exceeds a certain amount,it will have a drought stress effect on the plant and affect the plant growth.6.The correlation fitting of each index showed that IWUE was significantly positively correlated with yield.The principal component analysis was used to evaluate the yield benefit.The comprehensive score of T1W3 was the highest,and the best tillage and irrigation mode of maize in Ningxia Yellow River irrigation area was T1W3. |
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