核桃凋落叶分解对小麦生长及生理特性的影响

采用盆栽试验,研究了核桃(Juglans regia)凋落叶分解对小麦(Triticum aestivum)生长及抗氧化酶系统、渗透调节物质含量的影响。试验设置A1(30 g/盆)、A2(60 g/盆)、A3(90 g/盆)和对照(CK)4个凋落叶水平,将各处理的凋落叶分别与8 kg土壤混合后装盆。同时设置补充试验,将称好的核桃凋落叶蒸煮12 h,先后用80%丙酮和乙醇充分浸泡24 h,再蒸煮12 h,其他处理方法和条件相同,观测分析浸提蒸煮后的核桃凋落叶在施入土壤后对受体植物的影响。结果表明:核桃凋落叶分解(0—160 d)明显抑制了小麦茎秆地径、茎高、株高、地上部分干重,并随凋落叶量的增加抑制作用增强;随凋落叶量的增加,75—115 d小麦叶片超氧化物歧化酶SOD活性增强,但过氧化氢酶CAT和过氧化物酶POD活性显著低于CK但各凋落叶处理之间变化不明显;75—95 d小麦叶片丙二醛MDA含量变化不明显,115 d时随凋落叶量增加MDA含量显著增加;75—115 d随凋落叶量的增加可溶性糖含量显著增加,但可溶性蛋白含量呈现出下降的趋势;各处理凋落叶对小麦的化感综合效应CE均表现为抑制效应,0—115 d抑制效应增强,115 d后抑制效应减弱,这是由于核桃凋落叶在土壤中分解释放的有害次生代谢物质已明显减少;在补充试验中,各处理间无明显形态差别,CK、B1(30 g/盆)和B2(60 g/盆)水平下各生长指标差异不显著(P0.05),B3(90 g/盆)水平下化感效应指数RI的绝对值与A3相比明显减小,表明在一定的凋落叶施入量范围内,其对土壤物理性质的影响和对小麦根系生长的物理阻隔不会显著抑制小麦的生长。综合各项指标,表明核桃凋落叶分解过程中释放的次生代谢物质显著抑制了小麦生长和生理特性。

Effects of decomposing leaf litter of Juglans regia on growth and physiological characteristics of Triticum aestivum

A pot experiment was conducted to study the effects of decomposing leaf litter of Juglans regia on the growth, antioxidase system, and osmoregulation substances content of Triticum aestivum. Each pot contained 8 kg soil mixed with leaf litter (0 g/pot, CK; 30 g/pot, A₁; 60 g/pot, A₂; and 90 g/pot, A₃). Supplementary experiment was conducted as following: Leaf litter of Juglans regia was steamed for 12 h, then soaked in 80% acetone and alcohol for 24 h respectively, and then steamed again for 12 h, the other methods were the same as above. The results showed that: During 0-160 d, the ground diameter, stem height, plant height, and dry weight aboveground of T. aestivum were inhibited significantly, and the inhibition effect was getting stronger with the increasing amount of the leaf litter addition; During 75-115 d, the activity of superoxide dismutase (SOD) increased with the increasing amount of leaf litter, while the activities of catalase(CAT) and peroxidase(POD) under leaf litter treatment were significantly lower than control and the differences between all litter treatments were not significant; During 75-95 d, there was no obvious difference of in leaf Malondialdehyde(MDA) content. On 115 d, the soluble sugar contents of wheat leaf increased significantly with the increasing amount of leaf litter, while the protein contents showed a significant downward trend; The allelopathic compound effects(CE) of all litter treatments were negative, and the inhibition effect was getting stronger over time, bue after 115 d it decreased, the reason might be that the allelochemicals of leaf litter of Juglans regia had obviously reduced or almost no longer released; In supplementary experiment, there was no obvious difference of morphological feature and no significant difference in growth indicators between B₁ (30 g/pot), B₂ (60 g/pot) and CK, and the absolute value of RI under B₃ (90 g/pot) was significantly decreased compared with the one under A₃, this indicated that Triticum aestivum was not significantly inhibited by the effects of leaf litter on soil physical properties and physical barrier of root growth. Taking into account all parameters, the growth and physiological characteristics of Triticum aestivum were significantly affected by the allelochemicals released from the decomposing leaf litter of Juglans regia.