水氮耦合对大豆生长发育的影响 Ⅱ.水氮耦合对大豆生理特征的影响

EFFECTS OF WATER-NITROGEN COUPLING ON THE GROWTH AND DEVELOPMENT OF SOYBEAN Ⅱ.Effects of Water-Nitrogen Coupling on the Physiological Characteristics of Soybean

通过大豆生长发育各阶段的不同水氮处理,阐明水氮耦合对大豆光合速率、蒸腾速率、气孔导度的影响。结果表明:1、在土壤水分“特涝”条件下,在R2和R4期,气孔导度有不同程度的降低,而蒸腾速率总体有升高趋势,增施N肥降低光合速率、蒸腾速率、气孔导度,对大豆产量形成不利;2、在土壤水分“充足”条件下可以提高光合速率、蒸腾速率、气孔导度,但随着生育期的推进而递减,增施N肥可以提高光合速率、蒸腾速率、气孔导度,对大豆产量形成有利;3、在土壤水分“略旱”条件下,导致各生育时段的光合速率、蒸腾速率、气孔导度降低,特别是R2-R5期,增施N肥可以调节水分对光合速率的作用,同时提高蒸腾速率、气孔导度,增强对逆境胁迫的适应能力;4、在土壤水分“特旱”条件下,光合速率、蒸腾速率、气孔导度降低,增施N肥不能对大豆生理特性起到调节作用,而土壤恢复适宜水分后,N肥对大豆受旱恢复生长的速度起到一定的调节作用。大豆V6期遭遇旱、涝水分条件,全生育期均会受到不同程度的影响,但是随着生育期的推进,这种影响呈递减的趋势。

A pot experiment was conducted for two years to evaluate the effects of water-nitrogen coupling on the physiological characteristics of soybean at different stages of the growth and development. The results showed that： 1） under the condition of over-waterlogging the photosynthetic rate （P） of soybean declined significantly and turned to be more seriously at later stage, at the stages of R2-R4 period and the stomatal conductance （C） decreased as well, but the transpiration rate （E） increased accordingly. The increased application of N-fertilizer would give rise to the decline of P, C and E , which explained the yield loses of soybean; 2） when exposed to the abundant water condition , the P, C and E increased significantly, but they were on the way to decreasing with the growing of soybean plants,the increased application of N-fertilizer would lead to the increase of P,C and E , which account for the high yield of soybean; 3）the condition of a little drought made the P,C and E declined at different stages, especially, during R2-R5 period, increasing the application of N-fertilizer could readjust the effects of water on P and increase C, E and enhance the adaptability to adversity stress; 4）over-drought treatment caused the P, C and E decline so significantly that the effects of water on the physiological characteristics of soybean could not be readjust by increasing the application of N-fertilizer. When suitable soil moisture resumed, the application of N-fertilizer would affect and further restore the growth speed of soybean in the wake of drought stress. In exposure to waterlogging or drought stress at V6 stage, soybean would suffer by different degrees at later stages of the growth and development though on the way to decreasing gradually. Comparatively, R2-R4 were the crucial stages that accounted for the yield, and water fertilizer measures should be conducted. Conclusively, under different water conditions regulating the application of N-fertilizer could ensure the growth and development of soybean and reduced the yield loses. Under the waterlogging condition, increasing N-fertilizer is harmful to soybean, but it will be useless under the drought condition. Increasing N-fertilizer applying is helpful to soybean under the condition of abundance, fitting and a little drought.