In the present study, the mung bean cv. NM-13-1Tol was selected as drought-tolerant and NM-54Sens as drought-sensitive. The effects of progressive drought (16 days) on the photosystem II (PSII) activity was assessed using OJIP and JIP-test in the selected two mung bean cultivars differing in drought tolerance. Drought stress reduced the relative water content to 70% (at threshold) and 62% (below the threshold) in cv.NM-13-1Tol and NM-54sens , respectively. The greater reduction in quantum yield of PSII in cv.NM-54sens due to drought stress was due to PSII photodamage. Raw OJIP induction curves and Fo and Fm normalised curves showed that significant changes in fluorescence occurred at the O, J, I and P steps only in cv. NM-54sens . Double normalised differential kinetics indicated adverse effects at the antennae, oxygen evolving complex and intersystem electron acceptors in cv.NM54sens . Moreover, JIP-test analysis showed that drought stress caused a greater decrease in performance index (PIABS ) in cv.NM-54sens as compared to that in cv. NM-13-1Tol , which is associated with an increase in Vj , rate of accumulation of closed reaction centres (Mo ), energy fluxes for absorption (ABS/RC), trapping (TRo /RC), electron transport (ETo /RC), and dissipation of absorbed energy as heat (DIo /RC). In conclusion, two-week drought stress reduced the RWC below the threshold in cv.NM54sens , which resulted in damages at the donor and acceptor sides of PSII. However, cv.NM-13-1Tol somehow maintained the RWC around the threshold and thus protected PSII. Of various JIP-test parameters, PIABS , Fv /Fm , Vj , and Mo are key indicators of drought stress tolerance in mung bean cultivars.

中文翻译：

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将绿豆中叶绿素 a 荧光的变化与干旱胁迫敏感性联系起来 [Vigna radiata (L.) Wilczek]

在本研究中，绿豆 cv。NM-13-1Tol 耐旱，NM-54Sens 耐旱。在选定的两个耐旱性不同的绿豆品种中，使用 OJIP 和 JIP 测试评估渐进性干旱（16 天）对光系统 II (PSII) 活性的影响。干旱胁迫使 cv.NM-13-1Tol 和 NM-54sens 中的相对含水量分别降低至 70%（阈值）和 62%（阈值以下）。由于干旱胁迫导致 cv.NM-54sens 中 PSII 量子产率的更大降低是由于 PSII 光损伤。原始 OJIP 诱导曲线和 Fo 和 Fm 归一化曲线表明，仅在 cv. NM-54sens 。双归一化微分动力学表明对触角有不利影响，cv.NM54sens 中的氧演化复合物和系统间电子受体。此外，JIP 检验分析表明，与 cv.NM-54sens 相比，干旱胁迫导致 cv.NM-54sens 的性能指数 (PIABS) 下降幅度更大。NM-13-1Tol ，这与 Vj 的增加、闭合反应中心的积累速率 (Mo)、吸收能量通量 (ABS/RC)、俘获 (TRo /RC)、电子传输 (ETo /RC) 相关，以及吸收的能量作为热量的耗散 (DIo /RC)。总之，两周的干旱胁迫将 RWC 降低到 cv.NM54sens 的阈值以下，这导致 PSII 的供体和受体侧受损。然而，cv.NM-13-1Tol 以某种方式将 RWC 保持在阈值附近，从而保护了 PSII。各种JIP-test参数，PIABS , Fv /Fm , Vj ,