盐碱胁迫对海岛棉幼苗生物量分配和根系形态的影响

为探求海岛棉幼苗生物量分配和根系生长对混合盐碱胁迫的响应,探索海岛棉幼苗对混合盐碱胁迫的适应特点,以新疆阿克苏地区主栽海岛棉品种新海31号(XH31)、新海35号(XH35)、新海43号(XH43)及新海48号(XH48)为试材,采用NaCl、Na_2SO_4和NaCl、NaHCO_3以物质的量1∶1混合分别模拟中性盐混合盐(中性盐)和碱性盐混合盐(碱性盐)2种盐类型,总盐浓度(Na~+)0(CK)、120、180、240、300、360 mmol/L,对2种盐胁迫下不同浓度海岛棉幼苗生物量、根系长度、根系体积以及根系表面积等海岛棉幼苗根系形态特征指标变化差异以及不同茎级的根系形态特征进行了分析。结果表明,中性盐下,盐浓度在0—180 mmol/L时,对海岛棉幼苗的根系总长度、总表面积、总体积、总根尖数有显著的促进的作用或不显著的抑制作用,尤其盐浓度为120 mmol/L对海岛棉幼苗细根(0d0.5 mm)的长度有显著的促进作用;大于180 mmol/L后,随着盐浓度的增加各项根系参数均显著减小;碱性盐下,除新海31号的总根尖数、细根及中根根尖数在120 mmol/L的盐浓度下比CK增加,其余处理均随着盐浓度的增加再减小;地上部生物量、根系生物量及根冠比在两种盐下随着盐浓度的增加逐渐减小,减小程度也由小变大。低盐(120 mmol/L)环境能促进细根的伸长,使海岛棉幼苗可以更加多的吸收养分和水分,这是根系接触低盐环境时做出的响应,高盐环境对海岛棉幼苗造成较大的损伤。

Effects of saline-alkali stress on biomass allocation and root morphology of Sea Island cotton seedlings

Saline-alkali stress has always been a key factor restricting crop production in Xinjiang. Sea Island cotton is one of the main cash crops in Xinjiang and an important textile raw material. This experiment is based on the main Island cotton varieties Xinhai 31 (XH31), Xinhai 35 (XH35), Xinhai 43 (XH43) and Xinhai 48 (XH48), in the Aksu area of Xinjiang, involving treatment with neutral salt mixed with NaCl and Na₂SO₄ at 1:1 mole ratio and treatment with alkali salt mixed with NaCl and NaHCO₃ at 1:1 mole ratio. The objective was to explore the response of biomass allocation and root growth in Sea Island cotton seedlings to mixed saline-alkali stress. Total salt concentrations (Na⁺) in the different treatments were 0(CK), 120, 180, 240, 300, and 360 mmol/L. The differences in root morphological characteristics of Sea Island cotton seedlings under the two salt stress conditions, including biomass, root length, root volume, and root surface area, and root system morphological characteristics at different stem levels, were analyzed. Under the condition of neutral salt, the total root length, total surface area, total volume, and total root tip number of Sea Island cotton seedlings increased significantly or decreased slightly at salt concentrations of 0-180 mmol/L, and the fine root length of Sea Island cotton seedlings increased significantly, especially at a concentration of 120 mmol/L. When the concentration was higher than 180 mmol/L, the root parameters decreased significantly with the increase in salt concentration. Under the condition of alkaline salts, the total number of root tips and fine and middle root tips of Xinhai 31 were higher than that of CK at 120 mmol/L salt concentration, and the other parameters decreased with the increase in salt concentration. The biomass and root-shoot ratio decreased gradually with the increase in salt concentration under the two salt treatments, and the degree of reduction increased from low to high. Low salt (120 mmol/L) environment can promote the elongation of fine roots, so that Sea Island cotton seedlings can absorb more nutrients and water, which is the response of roots when exposed to a low salt environment. High salt environment causes greater damage to Sea Island cotton seedlings.