摘要：

A pot experiment was conducted to study the effects of leaf litter decomposition of Juglans regia on the growth,photosynthetic and resistant physiology of the recipient plant spinach(Spinacia oleracea).Four levels of leaf litter addition were applied to soil including A_1(30 g/pot),A_2(60 g/pot),A_3(90 g/pot) and CK(no leaf litter added).1) When the leaf litter decomposed to 75 d,the plant height,taproot length,belowground and aboveground biomass of S.oleracea significantly decreased with more leaf litter addition;when the leaf litter decomposed to 95-115 d,the inhibition effect on the same indicators was weakened;the growth of S.oleracea was even promoted when leaf litter decomposed to 135 d.2) Before 115 d of leaf litter decomposition,the contents of chlorophyll and carotenoid in S.oleracea in all treatment were lower than those in CK,with the lowest at 75 d.However,when leaf litter decomposed to 135 d,the contents of chlorophyll of S.oleracea were significantly higher than that in CK.3) The net photosynthetic rate(P_n),stomatal conductance(G_s) and transpiration rate(T_r) of S.oleracea with leaf litter added were significantly lower than those in CK.Moreover,the intercellular CO_2 concentration(C_i) in treatment A_1 was lower than that in CK,while that in A_2 and A_3 was higher than in CK.4) The activity of superoxide dismutase(SOD),peroxidase(POD) and Catalase(CAT) in S.oleracea were first enhanced with the increase of leaf litter addition(75 d),then significantly decreased(95-115 d),and then significantly increased at last(135 d).The content of MDA did not show significant difference compared to that in CK(75 d),but significantly increased with leaf litter addition(95 d).But this increasing trend slowed down(115 d),and restored to normal condition(135 d).The results indicated that J.regia leaf litter has strong allelopathic effect on S.oleracea especially in the initial stage of J.regia leaf litter decomposition(75 d).The growth of S.oleracea is first inhibited probably because the application of leaf litter leads to oxidative damage of plant,inhibiting synthesis of chlorophyll and therefore reducing photosynthetic capacity.With further decomposition of leaf litter(after 135 d),the allelochemicals released from litter gradually decreases and the nutrient substance released from litter greatly increases,the decomposition of leaf litter turns to promote the growth of S.oleracea.

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