玉米‖花生茬口对冬小麦旗叶光化学活性的影响

为探明玉米‖花生茬口显著提高冬小麦旗叶的光合速率和产量的光反应机理,研究了玉米‖花生茬口(间作茬口,ICR)、玉米茬口(MCR)和花生茬口(PCR)及不同施磷水平对冬小麦播前土壤含水量、冬小麦花后旗叶的气体交换参数、光系统Ⅱ(PSⅡ)、光系统I(PSⅠ)及二者间的性能协调性的影响。结果表明,间作茬口较玉米茬口显著提高了冬小麦播前土壤含水量及旗叶的净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)和PSⅡ反应中心供(Wk)/受体侧(Vj)的活性,增强了单位面积吸收的光能(ABS/CSo)、捕获的能量(TRo/CSo)和进入电子传递的光能(ETo/CSo)。间作茬口较玉米茬口显著提高了冬小麦扬花期旗叶PSⅡ初级光化学最大量子产额(φpo)、转化效率(Ψo)、电子传递效率(δRo)及乳熟期的PSⅠ的性能(ΔI/Io)、PSⅡ与PSⅠ协调性(ΦPSⅠ/PSⅡ)和籽粒产量,较花生茬口显著提高了乳熟期的φpo和δRo值。施磷提高了Pn、ABS/CSo、TRo/CSo、ETo/CSo、φpo、Ψo、δRo、ΔI/Io和ΦPSⅠ/PSⅡ值。这说明间作茬口较玉米茬口提高了冬小麦旗叶光反应中心活性,从而提高净光合速率,重要原因可能是间作茬口能保持耕层较高的土壤含水量。

Photochemical activity in flag leaves of winter wheat when following maize,peanut, or a maize-peanut intercrop in a crop rotation

The aim of this research was to verify that photosynthetic activity of flag leaves and yield, in winter wheat, is enhanced when following a maize-peanut intercrop in a crop rotation. Winter wheat was sown into plots in a field experiment which had previously grown a maize-peanut intercrop (ICR), maize (MCR) or peanut (PCR), either without, or with phosphate fertilizer at 180 kg P₂O₅·ha^-1 (P₀ or P₁, respectively). Data gathered included: soil moisture content before wheat sowing, wheat flag leaf gas exchange parameters, and characteristics of photosystem Ⅱ (PSⅡ), photosystem Ⅰ (PSⅠ) and their interrelationships. Compared with MCR, ICR significantly (P<0.05) increased soil moisture content at wheat sowing, the net photosynthetic rate (P_n), stomatal conductance (G_s), transpiration rate (T_r), the performances of electron donor (W_k) and acceptor (V_j) sites of the electron transport chain in the PSⅡ reaction center in flag leaves of winter wheat; and enhanced the absorbed energy flux (ABS/CS_o), trapped energy flux (TR_o/CS_o), electron transport flux (ET_o/CS_o) per cross section (CS) in flag leaves of winter wheat. Compared to MCR, ICR significantly improved the maximum quantum yield of primary photochemistry (φ_po), energy conversion efficiency (Ψ_o), electron transfer efficiency (δ_Ro), PSⅠ performance (ΔI/I_o), coordination between PSⅡ and PSⅠ (Φ_PSⅠ/PSⅡ) in flag leaves, and the yield of winter wheat; and increased the φ_po and δ_Ro at the milk-stage of grain development, as compared to PCR. Supplying phosphate fertilizer increased the P_n, ABS/CS_o, TR_o/CS_o, ET_o/CS_o, φ_po, Ψ_o, δ_Ro, ΔI/I_o and Φ_PSⅠ/PSⅡ in flag leaves of winter wheat. The data indicate that intercropping peanut with maize in a crop rotation benefited the following crop in the rotation. In this experiment, following a maize-peanut intercrop, the activity of light reaction centers in flag leaves of winter wheat were enhanced, so the net photosynthetic rate was increased. Conservation of soil moisture during the maize-peanut intercrop phase of the rotation appears to be an important contributing factor in these results.