橡胶-作物农林复合系统中作物光合生理对光照亏缺的响应机制研究

For several decades, extremely high shade density limited intercropping practice in mature rubber plantation. Only few shade-like crops could be intercropped under this condition. Based on previous study, whole production cycle intercropping rubber plantation could be intercropped with many sun-like crops in the intercropping strip in mature stage of rubber under light limitation condition (amount to 18-36% of full length of sunlight). For example, yield of intercropped yam beam in rubber-yam beam agroforestry system was maintained while yield of intercropped peanut was significant reduced. Limitation of light was the dominant factor. Aimed at the mechanism of maintain yield of crop intercropped in this rubber plantation, we importantly determine the relationship between allocation and accumulation rate of photosynthate and net photosynthesis, light saturation point, light compensation point, etc. in situ and artificial shed. Furtherly, we determine the main activity of enzyme of photosynthesis, content of photosynthetic pigment. These aim to reveal mechanism of maintain or reduction of loss of yield of the two crops by how to adjusting its photosynthesis physiology to adapt the light limitation. The current study has a significant of theoretical instruction of revealing the mechanism of intercropped crops adjust its photosynthesis physiology to effect crop productivity under light limitation condition in rubber-crop system.

多年来，常规成龄胶园因郁闭度非常高，仅少数阴生作物适宜生长,可间作模式少。前期研究基础表明，成龄的全周期间作模式胶园在光照亏缺下（18-36%的全光照时长）仍可间作许多喜光作物。其中，间作豆薯产量得以维持，而间作花生则减产严重，光是主要影响因子。围绕该胶园间作作物在光照亏缺下维持生产力的机制的问题，通过大田和仿真大棚盆栽试验相结合的方法，重点研究光照亏缺下豆薯和花生的作物光合产物积累、分配与净光合速率、光饱合点、光补偿点等光合生理指标的关系；进一步地，从主要的光合酶活性、光合色素含量和组分，阐明影响光合能力的差异，以期达到揭示两种作物如何调控光合生理以适应光因子的制约,维持产量或减缓作物产量损失的机制。以上研究对揭示橡胶-作物系统中间作作物在光照亏缺环境下调控光合生理影响生产力的机制具有重要的理论指导意义。

成龄的全周期间作模式胶园在光照亏缺环境下仍可间作一些喜光作物，但不同作物的产量潜力差异明显。围绕一些作物在该类型胶园中间作如何能维持相对较高产量潜力的机制尚不明确的问题，以橡胶-豆薯和橡胶-花生农林复合模式为研究对象，测定光照强度、作物生物量、光合生理等指标，研究光照亏缺对不同喜光间作作物生产力的影响及可能的影响因素。结果表明，复合系统中间作区域的阳光直射时长为2-4h，而裸地对照接近11h，间作区域的光照强度日变化呈单峰型，间作区域平均光照强度为裸地对照的23.1-58.1%。间作作物的产量显著低于相应单作处理(P<0.05)，2018-2020年期间，间作豆薯产量在7.3-19.7 t/ha之间，为单作处理的58.2-73.2%；而间作花生产量仅为单作处理的17.4-32.4%。光照亏缺环境对间作豆薯和花生不同位置叶片的RuBP羧化酶活性没有显著影响，但显著提高叶绿素(特别是叶绿素b)含量 (P<0.05)，其光合能力亦低于相应单作处理。间作豆薯叶面积高于单作豆薯，而间作花生叶面积则较单作花生显著降低(P<0.05)。大棚模拟试验的研究结果进一步验证了大田试验所得的结论。综上所述，豆薯比花生更适合在橡胶-作物农林复合系统中进行间作，间作豆薯应该是通过维持较高的叶面积来捕获光能并制造更多的光合产物，弥补光合能力的下降，从而维持相对较高的生产力。以上研究对揭示橡胶-作物系统中间作作物在光照亏缺环境下调控光合生理影响生产力的机制具有重要的理论指导意义。