Legumes have a distinct morpho-physiological response to reduced sunlight, but their capacity to adapt to the levels of shading due to intercropping systems is not sufficiently understood. Such adaptation to shade—60% of full sun in terms of physiological attributes—was examined in cowpea (Vigna unguiculata Savi), lablab (Lablab purpureus Adans.), lima bean (Phaseolus lunatus), pigeonpea [Cajanus cajan (L.) Millsp.], and pole bean (Phaseolus vulgaris). Although the capacity of photosynthetic machinery decreased under shade, the capacity continued to exceed the actual rate of photosynthesis. Compared with those under full sun, leaves under shade were thinner (specific weight only 56% of that under full sun), larger (surface area greater by 54.7%), and recorded a 15% higher leaves/stem ratio (by weight) and a 25.6% higher leaves/total dry weight ratio. However, the concentration of chlorophyll pigments per unit weight and per unit surface area was significantly higher in leaves under shade. Water stress was probably higher for leaves under full sun given the higher canopy temperatures and lower relative water content. At final biomass harvest, across the species shading has reduced the biomass 32% in 2009 and 34.6% in 2010 over unshade. Biomass was greater in lima bean (413 g m⁻²), and pigeonpea (408 g m⁻²) then lowest in lablab (180 g m⁻²) and cowpea (216 g m⁻²). Of the five legumes tested, lablab and cowpea showed the greatest tolerance to shade and therefore are better suited to the low-light environment of intercropping.

中文翻译：

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豆科植物在生物量积累、叶片光合作用和叶绿素色素减少日照下的耐荫性反应

豆科植物对减少的阳光有明显的形态生理反应，但它们适应间作系统引起的遮荫水平的能力尚不清楚。这种对遮荫的适应——就生理属性而言是全日照的 60%——在豇豆 ( Vigna unguiculata Savi)、lablab ( Lablab purpureus Adans.)、青豆 ( Phaseolus lunatus )、木豆 [ Cajanus cajan (L.) Millsp .] 和极豆 ( Phaseolus vulgaris). 尽管光合作用机械的能力在阴凉处有所下降，但仍继续超过实际的光合作用速率。与全日照相比，阴凉处的叶片更薄（比重仅为全日照的 56%），更大（表面积增加 54.7%），叶/茎比（重量比）高 15%，叶子/总干重比高出 25.6%。然而，每单位重量和每单位表面积的叶绿素色素浓度在阴凉处的叶子中显着更高。考虑到较高的冠层温度和较低的相对含水量，在充足阳光下叶片的水分胁迫可能更高。在最终的生物量收获时，与未遮蔽相比，2009 年整个物种的生物量减少了 32%，2010 年减少了 34.6%。利马豆的生物量更大（413 克⁻² ) 和木豆 (408 gm ^-2 ) 然后最低的是 lablab (180 gm ^-2 ) 和豇豆 (216 gm ^-2 )。在测试的五种豆科植物中，lablab 和 cow 豆表现出最大的耐荫性，因此更适合间作的弱光环境。