Key Laboratory of Crop Physiology, Ecology, and Genetic Breeding, Ministry of Education/College of Agronomy, Jiangxi Agricultural University, Nanchang, 330045, China.
Agricultural Meteorology Center of Jiangxi Province/Meteorological Bureau of Nanchang County, Nanchang, 330096, China.
Plant Physiol Biochem. 2023 Jul;200:107744. doi: 10.1016/j.plaphy.2023.107744. Epub 2023 May 12.
Soil-potassium (K) low availability and drought stress are limiting factors to crop productivity in arid and semiarid regions. A pot experiment with four K soil supplies (0, 60, 120 and 180 KO kg ha) and exposed to drought stress with 50 ± 5% field capacity was performed to investigate the function of K in protecting sesame plants from the adverse effects of drought based on the related physio-biochemical traits. The water stress was applied during flowering by withholding water for 6 days, and then rewatering to a well-watered level (75 ± 5% field capacity). Results showed that drought stress substantially reduced leaf relative water content (RWC), stomatal conductance (G), transpiration rate (T), photosynthetic rate (P), maximum PSII yield (F/F), and actual quantum yield of PSII (Ф), leading to greater non-photochemical quenching (qN) and stomatal limitation (L), thereby resulting in a decreased yield in contrast with well-watered sesame plants. Incidentally, K was more effective in promoting yield production under drought stress relative to well-watered conditions, and the optimal K application was 120 kg ha, which primarily attributed to the enhanced photosynthetic and plant water retaining ability. Specifically, plants receiving K supply showed greater leaf gas exchange traits, higher F/F and Ф values, and superior water use efficiency as compared to K-deficiency plants in both water regimes. Moreover, K can ameliorate the adverse effects of drought by improving salicylic acid (SA) while conversely decreasing abscisic acid (ABA) and jasmonic acid (JA) concentrations that are involved in controlling stomatal closure. It is noted that significant correlations between the seed yield, gas exchange parameters, and aforementioned endogenous hormones were observed. In conclusion, the K application can improve the sesame plant's potential to maintain functionality regarding photosynthetic response and phytohormone regulation under drought stress, and ultimately, enhancing the sesame's productivity.
土壤钾（K）供应不足和干旱胁迫是干旱和半干旱地区作物生产力的限制因素。本试验采用盆栽方法，设置 4 个土壤钾供应水平（0、60、120 和 180 KO kg ha），在开花期进行 50±5%田间持水量的干旱胁迫处理，以研究钾在保护芝麻免受干旱不利影响方面的作用，相关生理生化特性。通过停水 6 天来施加水分胁迫，然后再浇水至充分供水水平（75±5%田间持水量）。结果表明，干旱胁迫显著降低了叶片相对含水量（RWC）、气孔导度（G）、蒸腾速率（T）、光合速率（P）、最大 PSII 产量（F/F）和 PSII 的实际量子产量（Ф），导致非光化学猝灭（qN）和气孔限制（L）增加，与充分供水的芝麻相比，产量降低。此外，与充分供水条件相比，干旱胁迫下钾更有效地促进产量形成，最佳钾施用量为 120 kg ha，这主要归因于增强了光合作用和植物保水能力。具体而言，与缺钾植物相比，在两种水分条件下，施用钾的植物表现出更高的叶片气体交换特性、更高的 F/F 和 Ф 值以及更高的水分利用效率。此外，钾可以通过提高水杨酸（SA）含量，同时降低参与控制气孔关闭的脱落酸（ABA）和茉莉酸（JA）浓度，来减轻干旱的不利影响。值得注意的是，种子产量、气体交换参数与上述内源激素之间存在显著相关性。综上所述，钾的施用可以提高芝麻在干旱胁迫下维持光合作用响应和植物激素调节功能的潜力，从而提高芝麻的产量。
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