干旱胁迫下红砂幼苗非结构性碳水化合物动态变化特征

该试验以荒漠区主要建群种红砂幼苗为研究对象,设置适宜水分(CK)、轻度干旱(MD)、中度干旱(SD)和重度干旱(VSD)4个胁迫处理(即田间持水量的80%、60%、40%和20%),采用盆栽控水试验,分别测定干旱胁迫15、30、45和60 d时红砂幼苗的叶、茎、粗根和细根中非结构碳水化合物(NSC)及其组分的含量,分析不同胁迫强度下不同干旱持续时间红砂幼苗NSC的动态变化及各组分差异,以揭示红砂NSC对干旱胁迫的响应机制。结果表明:(1)干旱胁迫强度和胁迫持续时间对红砂幼苗不同器官NSC及其组分均有显著影响,其中胁迫持续时间对NSC动态变化的影响尤为显著。(2)干旱胁迫初期,红砂叶中的NSC含量呈下降趋势,而茎中的NSC含量呈上升趋势,粗根和细根中NSC含量在各胁迫处理下基本保持稳定。(3)干旱胁迫后期,红砂叶和茎中的可溶性糖、淀粉和NSC含量逐渐增加,而粗根和细根中的淀粉和NSC含量呈下降趋势(中度干旱除外),且这一时期重度干旱处理下各器官可溶性糖和NSC的含量明显高于CK。研究发现,重度干旱胁迫能显著诱导提高红砂幼苗不同器官中的NSC含量,并通过分解根中淀粉和增加叶片中可溶性糖含量的方式来调节细胞渗透势平衡,以维持细胞活力,进而保持红砂在干旱胁迫后期的存活。

Dynamic Changes of Non-structural Carbohydrate in Reaumuria soongorica Seedlings under Drought Stress

In this experiment, we used the seedlings of the main constructive species of Reaumuria soongorica in the desert area as the experimental material, and set four different water treatments including suitable water (CK), light drought stress (MD), moderate drought stress (SD) and serious drought stress (VSD), i.e., 80%, 60%, 40% and 20% of the water holding capacity in the field. The contents of non-structural carbohydrates (NSC) and their components in leaves, stems, coarse roots and fine roots of R. soongorica seedlings at 15 d, 30 d, 45 d and 60 d of drought stress were measured by pot water control experiment. The dynamic changes and differences of components of NSC in R. soongorica seedlings under different stress intensities and drought durations were analyzed, aim to reveal the response mechanism of R. soongorica NSCs to drought stress. The results showed that: (1) the intensity and duration of drought stress had a significant effect on the NSC and their components of different organs in R. soongorica seedlings, and the duration of stress had a particularly significant effect on the dynamic changes of NSC. (2) In the early stage of drought stress, the NSC content in leaves of R. soongorica showed a downward trend, while the NSC content in stems showed an upward trend, and the NSC content in coarse roots and fine roots remained basically stable under various stress treatments. (3) In the late stage of drought stress, the soluble sugar, starch and NSC content in leaves and stems of R. soongorica gradually increased, while the starch and NSC content in coarse roots and fine roots showed a downward trend (except moderate drought stress), and during this period, the contents of soluble sugar and NSC in various organs under serious drought stress treatment is significantly higher than those of CK. The study found that severe drought stress could significantly induce the increase of NSC content in different organs of R. soongorica seedlings, and the balance of cell osmotic potential was regulated by decomposing starch in roots and increasing soluble sugar content in leaves to maintain cell vitality, thus maintaining the survival of R. soongorica in the late stage of drought stress.