Abstract

Drought and heat are major abiotic stresses that usually occur simultaneously and cause significant yield losses in cereal crops including maize (Zea mays L.). First, ten genotypes of maize were screened using root length stress tolerance indices under heat (40 °C for 2, 4 and 6 h) and drought (−0.2, −0.4, and −0.6 MPa) stress. Two tolerant and two sensitive genotypes were selected and their growth and different biochemical traits were analyzed under drought stress (60% field capacity), heat stress (one cycle of 40 °C for 6 hours) and combined drought and heat stress. The results showed that drought stress had a predominant effect over heat stress, whereas combined drought and heat stress caused significant adverse effects on all parameters. The biochemical attributes such as total soluble sugars (TSS), proline, and total free amino acids (TFAA) were increased, whereas total soluble proteins (TSP) and nitrate reductase activity were decreased as compared to controls under all stress treatments. Biomass was positively correlated with the transpiration rate and TSP, while negatively related to leaf temperature and TFAA. The tolerant genotypes maintained higher proline, TSP, TSS, and TFAA contents and could be used for breeding for the adaptation to drought and heat under climate change.

摘要

干旱和高温是主要的非生物胁迫，通常会同时发生，并导致包括玉米在内的谷物农作物（玉米（Zea mays）L.）。首先，在热（40°C下持续2、4和6 h）和干旱（-0.2，-0.4和-0.6 MPa）胁迫下，使用根长胁迫耐受性指数筛选了十个基因型玉米。选择了两种耐性和两种敏感基因型，并在干旱胁迫（60％田间持水量），热胁迫（一个40°C的循环6小时）以及干旱和热胁迫相结合的条件下分析了它们的生长和不同的生化特性。结果表明，干旱胁迫比热胁迫具有主要影响，而干旱和热胁迫的结合对所有参数均产生明显的不利影响。在所有胁迫处理下，与对照相比，总可溶性糖（TSS），脯氨酸和总游离氨基酸（TFAA）等生化属性增加，而总可溶性蛋白（TSP）和硝酸还原酶活性降低。生物量与蒸腾速率和TSP呈正相关，而与叶片温度和TFAA呈负相关。耐性基因型保持较高的脯氨酸，TSP，TSS和TFAA含量，可用于育种以适应气候变化下的干旱和高温。