以玉米（Zea mays L ．）和马铃薯（Solanum tuberosum L ．）间作为研究对象，结合大田和盆栽试验，通过观测土壤蒸发、土壤含水量和作物蒸腾量，分析作物的水分竞争能力和间作的产量优势，研究间作对作物水分利用的影响特征与机理。大田试验结果表明：①玉米与马铃薯在同一时期的蒸腾量差异导致了两作物种植区域之间的土壤含水量差异；②间作的蒸腾量4424．07 t·hm －2显著大于单作玉米和单作马铃薯蒸腾量的加权平均值3612．27 t·hm －2（ P＜0．01）；③间作的土地当量比 LER（land equivalent ratio）＞1（P＜0．01），说明间作表现了增产优势。盆栽试验结果表明：①玉米和马铃薯在同一时期的蒸腾量存在差异，这意味着两作物种植区域的土壤含水量也存在差异（盆栽试验已基本消除土壤蒸发，土壤含水量主要受作物蒸腾影响）；②间作的蒸腾量51．79 kg·盆－1显著大于单作玉米和单作马铃薯蒸腾量的加权平均值48．36 kg·盆－1（P ＝0．011）；③作物的种间相对竞争力 RC（Relative com-petitive abilty）＞1（P＜0．001），说明玉米在种间水分竞争中占据优势地位；④玉米的蒸腾效率5．38 g·kg －1显著大于马铃薯的3．68 g·kg －1（P＜0．001）；⑤间作的蒸腾效率4．82 g·kg －1显著大于单作玉米和单作马铃薯蒸腾效率的加权平均值4．53 g·kg －1（P＜0．001）；⑥间作的土地当量比 LER ＞1（ P ＝0．001），说明间作表现了增产优势。以上结果说明：玉米和马铃薯在同一时期的蒸腾量差异可以导致它们种植区域之间的土壤含水量差异，进而使得在间作中，一种作物可以利用另一种作物种植区域的较多土壤水分，所以间作可以提高作物群体蒸腾量；玉米既具有较高的蒸腾效率，又在种间水分竞争中占据优势地位，因此玉米马铃薯间作可以提高作物群体蒸腾效率；蒸腾量和蒸腾效率的协同提高是该间作表现增产优势的重要原因。%It has been suggested that the over-yielding of intercropping is highly correlated to its efficient use of wa-ter resource .However ,the efficiently water usage of intercropping has not been comprehensively studied from the aspect of transpiration (the major form of crop water usage ) .In this study ,using intercropped maize (Zea mays L .) and potato (Solanum tuberosum L .) as the study object ,we combined the field and pot experiments to observe the soil evaporation , soil moisture content and crop transpiration .We also analyzed the competitive ability of intercropped crops and the yield advantage of intercropping ,and investigated the water usage feature and mechanism in intercropping .The field experi-ment result showed that the transpiration difference between maize and potato during the same period could lead to the soil moisture content difference .In addition ,the transpiration in intercropping of 4 424 .07 t·hm - 2 was significantly higher than the weighted average of that in sole maize and sole potato of 3 612 .27 t·hm - 2 (P < 0 .01) .Futhermore ,the land e-quivalent ratio (LER) of intercropping was > 1 ,indicating that the intercropping had the yield advantage .The pot exper-iment result showed that the transpiration of maize and potato was different during the same period .Namely ,the transpi-ration of maize was smaller than that of potato before the tuber initiation stage of potato and seedling stage of maize (P<0 .05) ,and higher than that of potato after that period ( P < 0 .05) .Additionally ,the transpiration in intercropping of 51 .79 kg·pot - 1 was significantly higher than the weighted average of that in sole maize and sole potato of 48 .36 kg· pot - 1 (P= 0 .011) .Moreover ,the relative competitive ability (RC) between the intercropped crops was > 1 ,indicating that maize had water competitive advantage .Also ,the transpiration efficiency of maize (5 .38 g·kg - 1 ) was significantly higher than that of potato (3 .68 g·kg - 1 ) ( P < 0 .001) .The transpiration efficiency in intercropping of 4 .82 g·kg - 1 was significantly higher than the weighted average of that in sole maize and sole potato of 3 .68 g·kg - 1 (P< 0 .001) .The land equivalent ratio (LER) of intercropping was > 1 ,indicating that the intercropping had the yield advantage .Overall , our results suggested that the transpiration of maize is different from that of potato during the same period .Thereby the intercropping can improve the crop transpiration .Maize has the higher transpiration efficiency than potato ,and maize has the water competitive advantage in intercropping ,allowing improvement of the crop transpiration efficiency .The improve-ment of both crop transpiration and transpiration efficiency in intercropping is an important reason for over -yielding in in-tercropping .
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