秸秆覆盖和滴灌制度对冬小麦光合特性和产量的影响

Effects of straw mulching and drip irrigation scheduling on photosynthetic characteristic and yield of winter wheat

确定不同滴灌和秸秆覆盖模式下的光合参数是理解其节水增产内因的基础。该研究通过4 a连续试验测定了覆盖和滴灌结合的6种处理(T1~T6分别表示低水覆盖、低水不覆盖、中水覆盖、中水不覆盖、高水覆盖和高水不覆盖处理)冬小麦旗叶的关键光合参数,并分析了光合参数处理间差异来源及其与作物产量的关系。结果表明:提高滴灌水量和覆盖处理能显著提高光合能力和最大羧化速率(P<0.05),而二者交互作用对光合参数影响不显著(P>0.1)。多重比较结果显示T5的光合参数最大(P<0.05);除2016年第一次测定外,T6和T3的相应值略低但与T5差异不显著(P>0.1);而T2的相应值则均显著低于T5(P<0.05),即高水处理下,覆盖与否对光合参数的影响不大,中水结合覆盖处理可使光合参数不显著降低,而低水处理下不覆盖则会使光合参数显著降低。处理间光合能力和最大羧化速率的差异能用叶片氮含量来解释,而所有年份的产量又均与光合能力和最大羧化速率分别线性相关(R^2>0.80)。因此,通过测定叶片氮含量,可以推算光合能力和最大羧化速率,研究结果可为产量估算提供参考。

Determining the photosynthetic parameters is the basis for understanding the physiological causes of water saving and yield increasing under drip irrigation modes. In this study, intrinsic photosynthetic parameters were determined during four years experiments in winter wheat field treated with six drip irrigation modes （T1 to T6, stands for treatments of lower irrigation amount with straw mulch, lower irrigation amount without straw mulch, moderate irrigation amount with straw mulch, moderate irrigation amount without straw mulch, higher irrigation amount with straw mulch, and higher irrigation amount without straw mulch, respectively）. The differences in photosynthetic parameters among treatments were statistically analyzed, and the correlations between photosynthetic parameters and crop yield were analyzed. The results showed that increasing irrigation amount and straw mulch enhanced the apparent photon quantum efficiency （a）, photosynthetic capacity （Amax）, maximum carboxylation rate （Vcmax） and maximum electron transfer rate （Jmax）, respectively. However, the interaction effects of irrigation amount and mulching on photosynthetic parameters were not significant （p 〉 0.1）. The effect of drip irrigation on apparent quantum efficiency （a） was significant （P 〈 0.05） during the late periods of the heading and grain filling stages, while the effect of straw mulch on a was not significant （P 〉 0.1）. The effect of straw mulch and drip irrigation on Amax show significant （P 〈 0.05） seasonal differences. The effects of drip irrigation on Vcmax and -/max were significant （P 〈 0.05） during the mid-season periods of the heading and grain filling stages, while the effects of straw mulch were significant （P 〈 0.05） during the later periods of the heading and grain filling stages. The results of multiple comparisons showed that the photosynthetic parameters of T5 were the highest （P 〈 0.05）. Except for the measurements in 2016, the corresponding values of T6 and T3 were slightly lower but with no significant difference from those of T5 （P 〉 0.1）. However, the corresponding values of T2 were significantly lower （P 〈 0.05） than those of T5. These results suggested that, under higher irrigation amount, photosynthetic parameters were not affected significantly （P 〉 0.05） by mulching, but under lower irrigation amount, the parameters significantly （P 〈 0.05） decreased if treated with no mulching. The average values of Amax during the four years from T1 to T6 were 29.59, 26.45, 31.44, 28.68, 32.42 and 30.90 μmol/（m2·s）, respectively. The average values of Vcm^x during the four years from T1 to T6 were 121.42, 107.68, 133.42, 113.55, 141.83 and 129.95 μmol/（m2·s）, respectively. From the point of view of reducing the amount of irrigation, T3 irrigation scheduling can be used as an optimal strategy for winter wheat under drip irrigation with straw mulch, indicating that 65% to 85% of the field capacity was used as the lower and upper limits of soil moisture control. The management practices of drip irrigation with straw mulch can keep the higher photosynthetic capacity of flag leaf for winter wheat. The differences in Amax and Vcmax among treatments could be explained by the leaf nitrogen content （Nmass）. Grain yield for all years were also linearly related to Amax and Vcmax, respectively. Therefore, by measuring Arm one can estimate Amax and VCmax, thus achieving the yield estimates of winter wheat field in this area. In addition, the photosynthetic characteristic parameters can also be applied to the crop model to improve the accuracy of model prediction under different water and mulch regimes.