Soil Water Use And Photosynthetic Characteristics Of Different Wheat Varieties Under Soil-moisture Monitoring Supplemental Irrigation Conditions

In order to evaluate the effects of soil moisture on the photosynthetic characteristics of different wheat varieties,a field experiment was conducted in Shijiawangzi Village,Xiaomeng Town,Yanzhou City,Shandong Province,China,during the 2016-2017 and 2017-2018 wheat growing seasons.Two wheat varieties,Jimai 22(JM22)and Liangxing 99(LX99),were selected for the experiment.Based on the water content of soil layers at depths of 0-40 cm,five water treatments were used for each wheat variety,including no irrigation during wheat growth stages(W0),and irrigating until the relative moisture of the 0-40 cm soil layers during the wheat plant jointing and anthesis stages reached 65%(W1),70%(W2),75%(W3),or 80%(W4).The experiment used a split zone design,where the main zone was the wheat variety,and the sub zone was the relative moisture content of the soil.The differences in water and nitrogen uptake,and utilization characteristics of the two different wheat cultivars in relation to different soil moisture contents,and their physiological basis were evaluated.This data can be used to provide a theoretical basis for water-saving and high-yield wheat cultivation techniques.The results were as follows: 1 Differences in water consumption characteristics of different wheat varietiesDuring the two wheat growing seasons,under treatments W1,W2,and W3,the total irrigation and supplemental irrigation during the jointing stage,and the relative water content of the 40-120 cm soil layer were significantly lower for wheat variety JM22 than for wheat variety LX99.Supplementary irrigation water consumption at anthesis,soil water consumption,and its proportion to total water consumption and soil water consumption in the 40-120 cm soil layer were higher for wheat variety JM22 than for wheat variety LX99.In the W2 treatment,the water consumption,daily consumption,and consumption percentage at the stages from jointing to anthesis,and anthesis to maturity were all higher for wheat variety JM22 than for variety LX99.Under treatments W2 and W3,the relative water content and water potential of flag leaves at 14 d,21 d,and 28 d after anthesis were higher for wheat variety JM22 than for wheat variety LX99.These results indicate that wheat variety JM22 consumed less water before the jointing stage,and consumed more water after anthesis,which could make full use of soil water storage and allow for efficient water use.2 Differences in flag leaf photosynthetic characteristics and dry matter accumulation and distribution of different wheat varietiesDuring the two wheat growing seasons,under treatments W1,W2,and W3,the canopy photosynthetic effective radiation interception rate of wheat variety JM22 at 20 d and 30 d after flowering was higher than that of wheat variety LX99,and the transmittance was significantly lower in wheat variety JM22 than in wheat variety LX99.The flag leaf net photosynthetic rate,transpiration rate,and stomatal conductance of wheat variety JM22 at 14 d,21 d,and 28 d after anthesis were significantly higher than those of wheat variety LX99.Under treatments W2 and W3,the relative chlorophyll content,relative electron transfer rate,photochemical quenching coefficient,actual photochemical efficiency,maximum photochemical efficiency,and flag leaf sucrose synthase activity at 14 d,21 d,and 28 d after anthesis were higher in wheat variety JM22 than in wheat variety LX99.The accumulation of dry matter in the mature stage and its distribution in the grain,the distribution of the assimilate in the grain after anthesis,and its contribution to the grain were higher in wheat variety JM22 than in wheat variety LX99.These results indicate that the photosynthetic capacity,material production capacity,and dry matter transfer capacity of wheat variety JM22 were better than those of wheat variety LX99 during the middle and late filling stages.3 Differences in nitrogen accumulation and distribution in plants of different wheat varietiesDuring the two wheat growing seasons,under W1,W2,and W3 treatments,nitrogen accumulation in wheat plants during the jointing,anthesis,and mature stages was higher in wheat variety JM22 than in wheat variety LX99.The amount of nitrogen distributed in various organs at maturity,the amount of nitrogen transported into the grain from the vegetative organs before anthesis,and its contribution to the grain were higher in wheat variety JM22 than in wheat variety LX99.Under the W2 treatment,the soil nitrate nitrogen content in the 40-120 cm soil layer during anthesis and in the 60-140 cm soil layer during maturity were lower for wheat variety JM22 than for wheat variety LX99.These results indicate that the accumulation of nitrogen in wheat plants,and the amount of nitrogen transported into the grains from vegetative organs during flowering were higher in wheat variety JM22 than in wheat variety LX99.4 Differences in yield and water and nitrogen use efficiency of different wheat varietiesDuring the two wheat growing seasons,under W1,W2,and W3 treatments,the grain yield,water use efficiency,partial nitrogen productivity,and irrigation efficiency were higher for wheat variety JM22 than for wheat variety LX99.Regarding the JM22 variety,the grain yield,water use efficiency and nitrogen partial productivity under the W2 and W3 treatments were significantly higher than under the other treatments.Regarding the LX99 variety,the grain yield,and nitrogen partial productivity were highest in treatments W2,W3,and W4,and the grain yield and nitrogen partial productivity were higher in these treatments than in treatment W1.The lowest grain yield and nitrogen partial productivity were recorded in treatment W0.These results indicate that irrigating the soil until the relative moisture of the 0-40 cm soil layers during the jointing and anthesis stages reached 70%(i.e.the W2 treatment)was the best treatment.Furthermore,wheat variety JM22 had higher water use efficiency and higher yield than variety LX99.