ICAR-National Rice Research Institute, Cuttack-753006, Odisha, India.
ICAR-National Rice Research Institute, Cuttack-753006, Odisha, India; and Corresponding author. Email:
Funct Plant Biol. 2020 Sep;47(10):891-903. doi: 10.1071/FP19364.
Besides genetic improvement for developing stress-tolerant cultivars, agronomic management may also add considerable tolerance against different abiotic stresses in crop plants. In the present study, we evaluated the effect of six different spacing treatments (S1: 10 × 10 cm; S2: 15 × 10 cm; S3:15 × 15 cm; S4:20 × 10 cm; S5: 20 × 15 cm; S6: 20 × 20 cm (row-row × plant-plant)) for improving submergence tolerance in rice. A high yielding submergence intolerant rice cultivar IR64 was tested against its SUB1 QTL introgressed counterpart (IR64-Sub1) for 12 days of complete submergence for different spacing treatments in field tanks. Relatively wider spaced plants showed higher individual plant biomass and early seedling vigour, which was particularly helpful for IR64 in increasing plant survival (by 150% in S6 over S1) under 12 days of submergence, whereas the improvement was less in IR64-Sub1 (13%). Underwater radiation inside the plant canopy, particularly beyond 40 cm water depth, was significantly greater in wider spacing treatments. Leaf senescence pattern captured by SPAD chlorophyll meter reading and chlorophyll fluorescence imaging data (Fm, Fv/Fm) taken at different time intervals after stress imposition suggested that there was lesser light penetration inside the canopy of closer spaced plants, and that it might hasten leaf senescence and damage to the photosynthetic system. The initial content of total non-structural carbohydrate (NSC) was higher in wider spaced plants of IR64, and also the rate of depletion of NSC was lesser compared with closer spaced plants. In contrast, there was not much difference in NSC depletion rate under different spacing in IR64-Sub1. Further, higher antioxidant enzyme activities in wider spaced plants (both IR64 and IR64-Sub1) after de-submergence indicated better stress recovery and improved tolerance. Taken together we found that wider spacing (row-row: 20 cm and plant-plant: 15 cm and more) can significantly improve submergence tolerance ability in rice, particularly in submergence intolerant non-Sub1 cultivar like IR64, perhaps due to better underwater light penetration, delayed leaf senescence and slower depletion of NSC reserve.
除了通过遗传改良来培育抗逆品种外，农艺管理也可以为作物提供相当大的非生物胁迫耐受性。本研究评估了 6 种不同种植密度处理（S1：10×10cm；S2：15×10cm；S3：15×15cm；S4：20×10cm；S5：20×15cm；S6：20×20cm（行-行×株-株））对提高水稻耐淹能力的影响。选用高产不耐淹水稻品种 IR64 及其 SUB1 QTL 导入系（IR64-Sub1）进行大田淹水试验，在不同种植密度处理下完全淹水 12 天。相对较宽的种植间距的植株表现出更高的单株生物量和早期幼苗活力，这对 IR64 在 12 天淹水条件下提高植株存活率（S6 比 S1 提高 150%）特别有帮助，而在 IR64-Sub1 中这种提高则较小（13%）。水下辐射在植物冠层内，特别是在 40cm 水深以上，在较宽的种植间距处理中显著增加。胁迫后不同时间间隔用 SPAD 叶绿素计读数和叶绿素荧光成像数据（Fm、Fv/Fm）捕获的叶片衰老模式表明，较密种植植株冠层内的光穿透较少，可能会加速叶片衰老和对光合作用系统的破坏。IR64 中较宽种植间距植株的总非结构性碳水化合物（NSC）初始含量较高，而且与较密种植植株相比，NSC 的消耗速率也较低。相比之下，在 IR64-Sub1 中，不同种植间距下 NSC 的消耗速率没有太大差异。此外，淹水后较宽种植间距植株（IR64 和 IR64-Sub1 ）中更高的抗氧化酶活性表明其具有更好的应激恢复能力和提高的耐受性。综上所述，我们发现较宽的种植间距（行-行：20cm，株-株：15cm 及以上）可以显著提高水稻的耐淹能力，特别是在不耐淹的非 SUB1 品种如 IR64 中，这可能是由于更好的水下透光性、延缓叶片衰老和较慢的 NSC 储备消耗。
