间作对桑树和谷子生长和光合日变化的影响

以桑树和谷子为研究材料,探讨了大田条件下,桑树-谷子间作对桑树和谷子的干物质生产、土地利用率和光合日变化的影响.结果表明:桑树-谷子间作条件下,间作桑树的株高、地茎、根长和枝条数分别比单作桑树增加了6.0％、13.7％、6.8％和14.8％,且间作桑树的产叶量比单作桑树增加了31.3％；间作谷子与单作比较,其株高和根长的变化不大.桑树-谷子间作增加了土地当量比,提高了土地利用率.单作、间作桑树和谷子叶片在12:00时均表现出明显的光合午休现象,且单作桑树的光合午休现象比间作桑树严重.桑树-谷子间作提高了中午时桑树叶片气孔导度和水分利用率,增加了桑树光合碳同化能力,抑制了桑树叶片实际光化学效率、电子传递速率和最大光化学效率的下降,从而减缓了桑树的“光合午休”现象.桑树-谷子间作能明显提高桑树叶片的光合生产能力.

Effects of Morus alba and Setaria italica intercropping on their plant growth and diurnal variation of photosynthesis

A field investigation was conducted to study the effects of intercropping Morus alba and Setaria italica on their dry matter production,land use efficiency,and diurnal variation of leaf photosynthesis.Under intercropping,the plant height,basal diameter,root length,and branch number of M.alba increased by 6.0%,13.7%,6.8%,and 14.8%,respectively,and the leaf yield of M.alba was increased by 31.3%,as compared with monoculture M.alba.In contrast,the plant height and root length of intercropped S.italica had no significant difference with those of monoculture S.italica.Intercropping enhanced the equivalent ratio and use efficiency of arable land.For both M.alba and S.italica in monoculture or intercropping,their leaf photosynthetic depression all occurred at midday(12:00),but the leaf photosynthetic depression of monoculture M.alba was heavier than that of intercropped M.alba.Intercropping promoted the leaf stomatal conductance(gs) and water use efficiency(WUE) of M.alba at midday,increased the photosynthetic carbon assimilation of M.alba,and inhibited the decline of M.alba leaf actual photochemical efficiency of PSⅡ(ΦPSⅡ),photosynthetic electron transport rate(ETR),and the maximal photochemical of PSⅡ(Fv/Fm),which might contribute to alleviate the leaf photosynthetic depression of M.alba at midday.It was concluded that M.alba and S.italica intercropping could obviously improve the leaf photosynthetic capacity of M.alba.