氯盐胁迫下氮素对西瓜根系生长的调控作用

Regulation of Nitrogen on Watermelon Root Growth under Chlorine Salt Stress

为揭示氯盐胁迫下氮素对西瓜根系的调节机制和提供西瓜氯毒害调控理论依据,以西瓜为供试作物,采用土培试验,研究不同施氮量(0,0.1,0.15,0.2,0.25 g/kg)对氯盐胁迫下西瓜根系的影响,并应用主成分分析法对各施氮量下根系生长情况进行综合评价。结果表明,(1)与不施氮相比,施氮0.15 g/kg处理可使西瓜根系生物量、干物质累积量、脯氨酸含量、可溶性糖含量、根系活力分别显著提高58.83%、20.83%、98.33%、70.37%和29.44%,丙二醛含量显著降低40.30%,同时使总根长、总根表面积、根尖数、分枝数分别显著增加103.42%、46.41%、64.44%、87.80%,总根体积和总根系直径分别减少23.05%和40.15%。(2)在本试验氯盐胁迫条件下,施氮0.14~0.17 g/kg时西瓜具有较理想的根系构型和较高的根系活力。(3)根系分枝数、根系活力、总根体积、根尖数可作为氯盐胁迫下氮素对西瓜根系生长影响的综合评价指标,各施氮水平对氯盐胁迫的缓解效果表现为0.15 g/kg>0.20 g/kg>0.10 g/kg>0.25 g/kg。可见,在氯盐胁迫下,适量施氮有助于西瓜建立良好的根系构型,提高根系渗透物质含量,降低细胞渗透势,减少根系丙二醛含量,维持较强的根系活力,增加根系生物量和干物质,缓解高浓度氯盐对西瓜生长的抑制作用。

In order to reveal the regulating mechanism of nitrogen on watermelon root under chlorine salt stress,and provide theoretical basis for chlorine toxicity control of watermelon,a soil culture experiment was conducted to study the effects of different N levels(0,0.1,0.15,0.2,0.25 g/kg)on watermelon root under the chlorine salt stress.Meanwhile,principal component analysis was used for comprehensive evaluation of root growth situation.The results showed that:(1)Compared with no nitrogen treatment,as nitrogen level was 0.15 g/kg,the root biomass,dry matter accumulation,proline content,soluble sugar content,and root activity were significantly increased by 58.83%,20.83%,98.33%,70.37%and 29.44%,and malondialdehyde content was significantly decreased by 40.30%,moreover,total root length,root surface area,root number,and branch number were increased 103.42%,46.41%,64.44%,and 87.80%,but total root volume and total root diameter were decreased by 23.05%and 40.15%,respectively.(2)Watermelon had ideal root system configuration and higher root activity when N was applied at 0.14-0.17 g/kg under chlorine salt stress in this test.(3)Root branch number,root activity,the total number of root volume could be used as the comprehensive index to evaluate influence of nitrogen on root growth under chloride salt stress,and alleviating effect of nitrogen level on chlorine salt stress was shown as 0.15 g/kg>0.20 g/kg>0.10 g/kg>0.25 g/kg.Visibly,it could conclude that a moderate amount of nitrogen helps watermelon to establish a good root system configuration,increase root penetration levels,and reduce cell osmotic potential and malondialdehyde content,maintain strong root activity,enhance biomass and dry matter,and thus alleviate high concentrations of chloride salt inhibition for the growth of watermelon.