The drought tolerance and capacity to recover after drought are important for plant growth and yield. In this study, two maize lines with different drought resistance were used to investigate the effects of different drought durations and subsequent re-watering on photosynthetic capacity, electron transfer and energy distribution, and antioxidative defense mechanisms of maize. Under short drought, maize plants decreased stomatal conductance and photosynthetic electron transport rate, and increased NPQ (Non-photochemical quenching) to dissipate excess excitation energy in time and protect the photosynthetic apparatus. With the increased drought duration, NPQ, antioxidase activity, PI_total (total performance index), ∆I/Io, ψ_Eo (quantum yield for electron transport)_, φ_Eo (efficiency/probability that an electron moves further than Q_A⁻), δ_Ro (efficiency/probability with which an electron from the intersystem electron carriers is transferred to reduce end electron acceptors at the PSI acceptor side) and φ_Ro (the quantum yield for the reduction of the end electron acceptors at the PSI acceptor side) were significantly reduced, while Y(NO) (quantum yield of nonregulated energy dissipation) and MDA (malondialdehyde) began to quickly increase. The photosynthetic rate and capacity of photosynthetic electron transport could not recover to the level of the plants subjected to normal water status after re-watering. These findings indicated that long drought damaged the PSI (photosystem I) and PSII (photosystem II) reaction center and decreased the electron transfer efficiency, and this damage could not be recovered by re-watering. Different drought resistance and recovery levels of photosynthetic performance were achieved by different maize lines. Compared with D340, D1798Z had higher NPQ and antioxidase activity, which was able to maintain functionality for longer in response to progressive drought, and it could also recover at more severe drought after re-watering, which indicated its higher tolerance to drought. It was concluded that the capacity of the energy dissipation and antioxidant enzyme system is crucial to mitigate the effects caused by drought, and the capacity to recover after re-watering was dependent on the severity and persistence of drought, adaptability, and recovery differences of the maize lines. The results provide a profound insight to understand the maize functional traits’ responses to drought stresses and re-watering.

中文翻译：

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玉米光合性能对干旱持续时间和复水的响应

干旱耐受性和干旱后恢复的能力对于植物生长和产量很重要。在本研究中，使用两个具有不同抗旱性的玉米品系来研究不同干旱持续时间以及随后的复水对玉米光合能力，电子传递和能量分布以及玉米抗氧化防御机制的影响。在短暂干旱下，玉米植物降低了气孔导度和光合电子的传输速率，并增加了NPQ（非光化学猝灭）以及时消散过量的激发能并保护了光合装置。随着干旱持续时间，NPQ，抗氧化酶活性，PI_总（总性能指数），ΔI/ Io，_ψEo（电子传递的量子产率）的增加_，φ_御（效率/概率比Q上的电子进一步移动_甲^- ），δ_滚装（与从系统间电子载流子的电子被转移到减少在PSI受体侧端电子受体效率/概率）和φ_滚装（用于还原PSI受体一侧的末端电子受体的量子产率）显着降低，而Y（NO）（非受控能量耗散的量子产率）和MDA（丙二醛）开始迅速增加。再浇水后，光合速率和光合电子传递能力无法恢复到处于正常水分状态下的植物水平。这些发现表明，长期干旱损害了PSI（光系统I）和PSII（光系统II）反应中心，降低了电子转移效率，这种损害无法通过补水来弥补。不同的玉米品种获得了不同的抗旱性和光合性能的恢复水平。与D340相比，D1798Z具有更高的NPQ和抗氧化酶活性，能够对干旱进行更长时间的维护，并且在重新浇水后甚至在更严重的干旱下也可以恢复，这表明其对干旱的耐受性更高。结论是能量消散和抗氧化酶系统的能力对于减轻干旱造成的影响至关重要，并且重新浇水后的恢复能力取决于干旱的严重性和持续性，适应性和恢复能力。玉米系。结果为了解玉米功能性状对干旱胁迫和补水的反应提供了深刻的见解。结论是能量消散和抗氧化酶系统的能力对于减轻干旱造成的影响至关重要，并且重新浇水后的恢复能力取决于干旱的严重性和持续性，适应性和恢复能力。玉米系。结果为了解玉米功能性状对干旱胁迫和补水的反应提供了深刻的见解。结论是能量消散和抗氧化酶系统的能力对于减轻干旱造成的影响至关重要，再浇水后的恢复能力取决于干旱的严重性和持续性，适应性和恢复能力。玉米系。结果为了解玉米功能性状对干旱胁迫和补水的反应提供了深刻的见解。