Abstract The performance of spring maize is severely hampered by high temperature at reproductive phase, causing marked reduction in grain yield. Early sowing of spring maize can be a good adaptive approach however, due to low temperature causes adverse effect on germinating seeds and young seedlings, thus being detrimental to early planting. Exogenous application of natural and synthetic growth promoting substances may induce tolerance against temperature constraints. For this purpose, field experiment was conducted to explore the potential of moringa leaf extract (MLE, 3%), sorghum water extract (SWE, 10 ml L − 1), ascorbic acid (ASA, 50 mg L − 1), salicylic acid (SA, 50 mg L − 1) and hydrogen peroxide (H2O2, 2 µM) as priming agents on maize hybrid under early and optimum sowing dates. The performance of early planted maize crop was severely influenced by low temperature in comparison to optimum sown crop nevertheless exogenous application of growth promoting substances proved effective in improving stand establishment, phenotypic behavior, key physiological and biochemical attributes of maize crop. Low temperature persuaded inhibition in growth of maize was mainly ameliorated by seed priming with MLE + H2O2 and SWE + ASA. It can be concluded that application of growth promoting substances as priming agents proved to be the most successful strategy in conferring better thermotolerance at early sowing through improved antioxidant defense system and physiological mechanism of spring maize. Better crop performance with combined application of natural and synthetic growth enhancers was linked to improvement in crop stand establishment, better growth and development, dry matter partitioning and yield attributes.

中文翻译：

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评估辣木叶提取物与合成促生长物质在早春条件下对玉米的综合反应

摘要 生育期高温严重影响春玉米的生产性能，导致籽粒产量显着下降。春玉米早播是一种较好的适应方式，但由于低温对发芽的种子和幼苗造成不利影响，不利于早播。天然和合成促生长物质的外源性应用可能会导致对温度限制的耐受性。为此，进行了田间试验以探索辣木叶提取物（MLE，3%）、高粱水提取物（SWE，10 ml L − 1）、抗坏血酸（ASA，50 mg L − 1）、水杨酸的潜力(SA, 50 mg L − 1) 和过氧化氢 (H2O2, 2 µM) 作为早期和最佳播种日期下玉米杂交种的引发剂。与最佳播种作物相比，早播玉米作物的性能受到低温的严重影响，但外源施用促生长物质被证明可以有效改善玉米作物的立树、表型行为、关键生理和生化特性。低温诱导的玉米生长抑制主要通过用 MLE + H2O2 和 SWE + ASA 引发种子来改善。可以得出结论，通过改善春玉米的抗氧化防御系统和生理机制，应用生长促进物质作为引发剂是在播种早期赋予更好的耐热性的最成功策略。