Abstract
Drought and heat damage can seriously affect the yield of various crops. The cost of prevention and control is relatively high, causing great losses to China’s agricultural economy and tremendously hindering economic development. Ginger is an herbaceous plant that is extremely sensitive to high temperatures and humidity. Drought and heat gravely threaten the cultivation and production of ginger tubers and seedlings. Therefore, it is important to screen drought- and heat-resistant ginger varieties and explore the regulation and response mechanisms of drought and heat tolerance in ginger for its highly efficient production and promotion in China. In this study, 26 germplasm resources of ginger, which are popular and widely planted in our country, were chosen and used as experimental materials, and the differences in the morphological and physiological indices between these ginger varieties were analyzed after drought and heat stress treatments for 7 days. The drought and heat tolerance capacities of 26 ginger germplasm resources were comprehensively assessed through a combination of the average membership function method, significance test, and cluster analysis. Compared with control, the leaf length, leaf width, leaf thickness, root length, surface area, root tip diameter, and number of root tips decreased by 0.3%−14.9%, 0.0%−16.5%, 1.1%−18.7%, 0.5%−68.6%, 3.9%−63.1%, 0.4%−29.9%, and 0.5%−55.2%, respectively under drought and heat stress treatment for 7 days. The water content of ginger leaves, photosynthetic pigment content, net photosynthetic rate , optimal/maximal quantum yield of photosystem II (PSII), and photochemical quenching coefficient (qP) exhibited decreasing trends after 7 days of drought and heat stress treatments. Compared to control, the relative conductivity and non-photochemical quenching coefficient (NPQ) were increased by 5.7%−142.0% and 9.2%−103.0%, respectively under drought and heat stress treatments. According to the capacity evaluation of drought and heat resistance, 26 ginger germplasm resources could be divided into four categories. The first category was extremely drought and heat resistance, including CDZIN091; the second category was highly drought and heat resistance, including CDZIN099, CDZIN101, CDZIN086, CDZIN080, CDZIN103, CDZIN096, CDZIN109 and CDZIN084; the third category was medium resistance to drought and heat, including CDZIN100, CDZIN090, CDZIN095, CDZIN098, CDZIN094, CDZIN089, CDZIN105, CDZIN106, CDZIN110, CDZIN111, CDZIN083, CDZIN108 and CDZIN012; the fourth category was weak drought and heat resistance, including CDZIN102, CDZIN081, CDZIN104, and CDZIN112. Through a comprehensive evaluation and a series of phenotypic and physiological analyses, an extremely drought- and heat-tolerant ginger variety (CDZIN091) was identified. The morphology and photosynthesis indexes of CDZIN091 were superior to that of other commonly used ginger germplasm resources, positioning it as a resilient ginger variety suitable for widespread cultivation in drought and heat-prone regions. These findings suggest that drought- and heat-tolerant ginger varieties can effectively regulate plant morphology and photosynthesis to adapt to challenging environmental conditions. This study contributes to a theoretical foundation for the development of drought- and heat-resistant ginger varieties.
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