不同间作模式对田间小气候特征及凤丹光合特性和种实性状的影响

Effect of different intercropping patterns on field microclimate characteristics and photosynthetic characteristics and seed and fruit traits of Paeonia ostii

以凤丹(Paeonia ostii T.Hong et J.X.Zhang)单作模式为对照,对凤丹与女贞(Ligustrum lucidum Ait.)、木瓜〔Chaenomeles sinensis(Thouin)Koehne〕、香椿〔Toona sinensis(A.Juss.)Roem.〕和胡桃(Juglans regia Linn.)间作模式下4月份至8月份田间小气候特征以及凤丹叶片叶绿素含量、光合特征参数和种实性状的变化进行了研究,并对影响凤丹叶片净光合速率的主要因子进行了分析。结果显示:不同间作模式下田间空气温度(Ta)、空气相对湿度(RH)和光合有效辐射(PAR)以及凤丹叶片的叶绿素含量、净光合速率(Pn)、气孔导度(Gs)、胞间CO2浓度(Ci)和蒸腾速率(Tr)的变化趋势总体上均存在差异。与凤丹单作模式相比,间作模式下田间Ta和PAR值均不同程度降低,但RH值变化不明显,其中,凤丹-女贞间作模式对田间Ta值的调节作用更明显,而在凤丹-木瓜间作模式下田间PAR值的降幅最大。在不同间作模式下,凤丹叶片叶绿素含量总体上显著高于凤丹单作模式,以凤丹-木瓜间作模式下叶绿素含量最高;总体上看,凤丹叶片的Pn、Gs和Tr值以及单株果荚数、单果种子数、果实直径、种子千粒质量和种子产量在凤丹-女贞和凤丹-香椿间作模式下均高于凤丹单作模式,但在凤丹-木瓜间作模式下则整体较低,而Ci值则明显波动。相关性分析及多元逐步回归分析结果显示:在不同间作模式下,凤丹叶片Pn值与气体交换参数和田间环境参数呈现不同程度的相关性,且影响Pn值的主要因子存在差异。其中,在凤丹-女贞间作模式下凤丹叶片Pn值随PAR值的升高而减小;在凤丹-木瓜间作模式下凤丹叶片Pn值随Ci、Ta和PAR值的升高而减小;在凤丹-香椿间作模式下凤丹叶片Pn值随Gs和Tr值的升高而增大,随Ci值的升高而减小;在凤丹-胡桃间作模式下凤丹叶片Pn值随RH值的升高而增大。综合分析结果表明:与凤丹单作相比,凤丹与其他树种间作可有效调节田间小气候,降低田间空气温度和光合有效辐射,且可不同程度影响凤丹叶片净光合速率和种实发育,其中,凤丹-女贞和凤丹-香椿间作模式对田间小气候的调节效应更强,可使凤丹叶片净光合速率增大,种子产量提高。

Taking monoculture pattern of Paeonia ostii T.Hong et J.X.Zhang as the control,change in field microclimate characteristics and leaf chlorophyll content,photosynthetic characteristic parameters and seed and fruit traits of P.ostii under intercropping patterns of P.ostii with Ligustrum lucidum Ait.,Chaenomeles sinensis(Thouin)Koehne,Toona sinensis(A.Juss.)Roem.and Juglans regia Linn.from April to August were studied,and the main factors affecting net photosynthetic rate in leaf of P.ostii were analyzed.The results showed that under different intercropping patterns,variation trends of air temperature(Ta),air relative humidity(RH)and photosynthetic active radiation(PAR)in field,and chlorophyll content,net photosynthetic rate(Pn),stomatal conductance(Gs),intercellular CO2 concentration(Ci)and transpiration rate(Tr)in leaf of P.ostia are different in general.Compared with monoculture pattern of P.ostii,field Ta and PAR values under intercropping pattern decrease in different degrees,but change in RH value is not obvious,in which,regulation effect of intercropping pattern of P.ostii-L.lucidum on field Ta value is more obvious,and the decreasing amplitude of field PAR value under intercropping pattern of P.ostii-C.sinensis is the largest.Under different intercropping patterns,chlorophyll content in leaf of P.ostii is significantly higher than that under monoculture pattern of P.ostii,and that under intercropping pattern of P.ostii-C.sinensis is the highest;on the whole,Pn,Gs and Tr values in leaf,and pod number per plant,seed number per fruit,fruit diameter,1000-grain mass and seed yield of P.ostii under intercropping patterns of P.ostii-L.lucidum and P.ostii-T.sinensis are higher than those under monoculture pattern of P.ostii,but those under intercropping pattern of P.ostii-C.sinensis are generally lower,while Ci value fluctuates obviously.The results of correlation analysis and multiple stepwise regression analysis show that under different intercropping patterns,Pn value in leaf of P.ostii shows different degrees of correlations with gas exchange parameters and field environmental parameters,and the main factors affecting Pn value are different.In which,Pn value in leaf of P.ostii under intercropping pattern affecting of P.ostii-L.lucidum decreases with the increase of PAR value;that under intercropping pattern of P.ostii-C.sinensis decreases with the increases of Ci,Ta and PAR values;that under intercropping pattern of P.ostii-T.sinensis increases with the increases of Gs and Tr values,and decreases with the increase of Ci value;that under intercropping pattern of P.ostii-J.regia increases with the increase of RH value.Comprehensive analysis result shows that compared with monoculture of P.ostii,intercropping of P.ostii with other tree species can effectively regulate field microclimate,reduce air temperature and photosynthetic effective radiation of field,and affect net photosynthetic rate in leaf and development of seed and fruit of P.ostii in different degrees,in which,intercropping patterns of P.ostii-L.lucidum and P.ostii-T.sinensis have stronger regulation effects on field microclimate,which can increase net photosynthetic rate in leaf of P.ostii,and increase seed yield.