Evaluation of drought resistance of native almond-rootstock varieties in Xinjiang, China

Screening for drought-resistant native almond-rootstock varieties provides germplasm for breeding programmes promising new drought-resistant almond cultivars worldwide. Therefore, in this study, two different drought-control experiments were conducted using six different almond rootstock seedlings. Leaf physiological and biochemical characteristics and root systems were measured under an 18-day period of progressive and a 60-day period of moderate drought conditions. Drought resistance was evaluated using subordinate-function-value analysis. Leaf physiological and biochemical characteristics showed that almond varieties 'S30,' 'S3,' and 'S47' were the most resistant, while peach × almond natural hybrids 'S64' and 'S28' showed intermediate drought resistance, and the local peach variety 'S-peach' was the most sensitive to progressive drought. A 60-day period of moderate drought significantly stimulated root growth in variety 'S47,' whereas it decreased specific leaf area (SLA) of 'S3' and increased root/shoot dry mass ratio in both 'S47' and 'S3' varieties. Moreover, the three almond varieties relied on different strategies for adaptation to drought and would serve as promising almond rootstocks for plantation in the arid regions of China.