二倍体、四倍体和六倍体小麦产量及水分利用效率

试验选用了6个不同染色体倍性的小麦进化材料（3个二倍体、2个四倍体和1个六倍体）,分别在不同水肥条件下研究其根系、地上生物量、产量、蒸腾耗水量和水分利用效率等指标,旨在阐明小麦进化材料产量及水分利用效率的差异及水肥条件对这些特性的影响。试验表明：不同倍性小麦进化材料的生物量、产量和水分利用存在显著的差异,而且水肥条件对其有显著影响。在染色体倍性由2n→4n→6n的进化过程中,小麦根系及地上生物量均先增加后降低,而产量却显著增加,这与收获指数的增加有关。小麦产量的大小顺序为：T.aestivum〉T.dicoccum〉T.dicoccoides〉Ae.squarrosa〉Ae.speltoides〉T.boeoticum。水分亏缺显著降低小麦的生物量、产量和收获指数;在不同水分条件下,增加施肥量有利于这些指标的增加。但是水分亏缺下,增加施肥却降低各小麦材料的根系生物量。随小麦的进化,蒸腾耗水量显著降低,这与其生育期缩短有关;而生物量水分利用效率和产量水分利用效率却显著升高,且后者的差异要大于前者。各小麦产量水分利用效率的大小排序与产量的完全一致。水分亏缺处理显著减少各小麦进化材料的蒸腾耗水量47％～52％，而显著增加生物量水分利用效率3％～40％；但水分亏缺对产量水分利用效率的促进作用却随染色体倍性的增加而降低，甚至降低六倍体小麦T.aestivum的产量水分利用效率19％。不同水分条件下，高肥处理均有利于蒸腾耗水量、生物量水分利用效率和产量水分利用效率的增加。

Grain yield and water use efficiency of diploid, tetraploid and hexaploid wheats

Three diploid (T. boeoticum, AA; Ae. speltoides, BB and Ae. squarrosa, DD), two tetraploid (T. dicoccoides, AABB and T. dicoccum, AABB) and one hexaploid (T. aestivum, AABBDD) wheats were evaluated for their root biomass, above-ground biomass, grain yield, water consumption for transpiration and water use efficiency under different water and nutrient regimes in order to (i) understand the differences in grain yield and water use efficiency among species across the ploidy level in the wheat (ii) assess the effects of water and nutrient regimes on these traits. Our results showed significant differences on biomass, grain yield and water-use between the ploidy levels in the wheat. In the evolution of wheat from diploid to tetraploid and hexaploid, root and aboveground biomass all increased firstly and then decreased, but grain yield increased significantly which is related to the remarkable increase of harvest index. The grain yield decreased in this order: T. aestivum > T. dicoccum > T. dicoccoides > Ae. squarrosa > Ae. speltoides > T. boeoticum. Water stress significantly decreased all of the measured growth indices. Under given water level, increase on nutrient supply increased aboveground biomass, grain yield and harvest index. However, at higher nutrient treatment root biomass decreased as compared to the lower nutrient treatment. With the sequence of wheat evolution, water consumption for transpiration decreased significantly which correlated with the decreasing crop maturity period. However, both water use efficiency for biomass and grain yield increased significantly in the evolution of wheat. For six wheat materials, water use efficiency for grain yield decreased in the same order with grain yield. Water stress significantly decreased water consumption for transpiration of six wheat genotypes by 47%-52%, but increased water use efficiency for biomass by 3%-40%. However, the increasing effect of water stress on water use efficiency for grain yield decreased with increase of wheat ploidies, and even decreased the water use efficiency for grain yield of T. aestivum by about 19%. Water consumption for transpiration, water use efficiency for biomass and grain increased under higher nutrient levels compared to those of low nutrient level across the different water levels.