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An interactive effect of simultaneous shade and drought stress on drought-tolerant and drought-sensitive cultivars of soybean was studied. As drought stress intensified, the net photosynthetic rate decreased in both cultivars due to reduced leaf area, relative water content, transpiration rate, stomatal conductance, chlorophyll content, and Rubisco activity which ultimately led to yield reduction. Moreover, the chlorophyll fluorescence parameters also decreased. Interestingly, a moderate shade was found helpful in alleviating the adverse effects of drought stress, specifically in resistant cultivar N12 where seed yield improved significantly under moderate drought conditions in contrast to the cultivar C103. In summary, the effect of drought stress on soybean depended on the irradiance conditions and shade could enhance soybean drought resistance, although this resistance was cultivar dependent. With appropriate cultivar selection, a moderate shade can help optimize yield and improve the performance of drought-exposed soybean. [ABSTRACT FROM AUTHOR]

Intercropping often results in increasing production than sole per unit land area, but the underlying mechanisms are poorly understood. Plants showed different physiological characteristics in intercropping and sole. However, less information was shown the relationships between plant aboveground biomass (AB), phosphorus accumulation (PB) and remobilization and the yield advantage. Here, field experiments were designed as split plot and carried out in 2012 and 2013 with three P levels (0, 40 and 80 kg P ha-1) in wheat (Triticum aestivum L.)/ maize (Zea mays L.) relay intercropping and sole. The study measured grain yield, AB and P accumulation and remobilization of wheat. Averaged grain yield of intercropping wheat increased 3.9 Mg ha-1 in 2012 and 2.7 Mg ha-1 in 2013 compared with that of the corresponding sole and the grain yield of intercropping wheat changed with the border row (BR) > the inner row (IR) > the sole wheat (SR), the grain yield in BR was contributed by 58.2% to intercropping wheat. The PA was consistent with AB accumulation, which in intercropping was higher than that in sole over the entire growing season. Close correlations between yield and AB remobilization and P remobilization were observed. The yield of BR was higher from 39.3% to 88.0% than that of SR wheat, as mainly attributed to more AB and P accumulation across the whole growing season and more remobilization from pre-anthesis to grain filling stage. More than 40 kg P ha-1 did not result in any further increasing in yield and did not enhanced the physiological processes associated with AB and P remobilization, indicating that P fertilizer and agronomic management should be intensified synchronously in field to achieve high yield and sustainability. [ABSTRACT FROM AUTHOR]