Effect of Shading on the Plasticity of Peanut Morphology and Structure
By clarifying the adaptability of peanut plant morphology and leaf structural plasticity to different degrees of shade,we aim to provide a reference basis for alleviating crop shade stress and improving the quality and efficiency of intercropping cultivation in the lower reaches of the Yellow River.The morphology and leaf structure plasticity of peanut plants under no shade(CK),moderate shade(S1,40% shade)and heavy shade(S2,80% shade)were investigated in a pot experiment using Huayu 36 as the research subject.The results showed that S1 and S2 significantly increased the height of main stem(30.59% and 51.87% ),length of first pair of lateral branches(21.83% and 36.40% ),and specific leaf area(32.86% and 59.22% ),and significantly decreased the number of branches(19.81% and 47.17% ),leaf area of single plant(20.87% and 41.52% ),yield(39.06% and 66.95% ),biomass(36.45% and 59.25% )and leaf stomatal density(9.19% and 18.53% ),but did not significantly affect the number of nodes in the main stem;the thickness of peanut leaf blades,thickness of the upper epidermis,thickness of the lower epidermis,thickness of the fenestrated tissues and thickness of the spongy tissues of S1 and S2 were significantly lower than those of CK,and showed a trend of S2<S1<CK.The number of chloroplasts per cell of S1 and S2 did not differ significantly from that of CK,but S1 was 21.44% higher than that of S2.The chloroplasts of S1 leaf cells were slightly flattened,and the number of basal lamellae was increased and densely distributed.The chloroplast peridium of S2 was partially damaged and missing,and the basal lamellae were ambiguous,the number of starch grains was significantly reduced,and the number of osmiophilic granules showed a tendency to increase.The plant morphology and leaf structure of peanut showed high plasticity,and the top ten indexes of plasticity were,in order,branch number,leaf area,specific leaf area,main stem height,leaf thickness,upper epidermal thickness,first pair of lateral branch length,chloroplast width,and palisade tissue thickness,stomatal area.Thus,the differences in morphology and leaf structure of peanut plants are their phenotypic adaptations and plastic responses to shade stress,expressing the survival strategies of peanut under different degrees of shade environments.