Drought and phosphorus deficiency are key factors limiting oat （Avena sativa） production in the Qinghai-Tibet Plateau. In order to elucidate the effects of water and phosphorus stress on oat growth， identify the primary limiting factors， and screen for key indicators of oats’ synergistic adaptation to water and phosphorus constraints. This study utilized 14 oat cultivars in pot experiments， with treatments including a control （CK）， low phosphorus stress （-P）， drought stress （-W）， and combined drought and low phosphorus stress （-W-P）. Additionally， this experiment measured 18 indicators， including agronomic traits， biomass， and phosphorus accumulation， among others. Results indicated that stress treatment significantly suppressed oat aboveground biomass and biomass of individual aboveground organs， spikelet number， grain per spike， and phosphorus accumulation at the 0.05 level. Moreover， the degree of inhibition is greater under combined stress than under single stress. Different indicators exhibited varying degrees of susceptibility to each factor， with water availability being the primary growth-limiting factor. Methods such as grey relational analysis and principal component analysis jointly identified grain biomass， aboveground biomass， spikelet number， grain per spike， belowground biomass， flag leaf area， and phosphorus accumulation in plants and grains as key indicators reflecting oats' tolerance to water and phosphorus stress. The findings of this study provide theoretical foundations and methodological guidance for the breeding and evaluation of drought-tolerant and low-phosphorus-tolerant oat cultivars on the Qinghai-Tibet Plateau.

Oats  /  Low phosphorus stress  /  Drought stress  /  Combined stress