Germination of pumpkin seeds under Cd stress

Abstract

Cadmium is a non essential element for plant growth, and its accumulation in plants can cause damage to a certain extent. The accumulation of heavy metals not only inhibits the growth and development of plants, but also threatens human health through the food chain. Therefore, the problem of heavy metal pollution cannot be ignored. Studies have shown that grafting can reduce the accumulation of cadmium in Pumpkin fruits, such as eggplants, providing new ideas for mitigating the impact of heavy metal pollution on agricultural products. Pumpkin (Cucurbita moschata (Duchesne ex Lam.) Duchesne ex Poir.) as an important vegetable crop, it has a well-developed root system and good affinity, and is often used as a grafting rootstock for melon crops. Seed germination is a crucial stage for evaluating plant cadmium tolerance. The evaluation of plant tolerance to heavy metals during germination is a widely recognized method internationally. Therefore, this study investigated the effects of cadmium stress on pumpkin seed germination and the tolerance of different pumpkin varieties to heavy metal cadmium under the same concentration (8mg/L-1 Cd2+) of heavy metal cadmium stress, in order to screen pumpkin resources that are tolerant to heavy metal cadmium stress and provide a basis for further screening of pumpkin rootstocks that are tolerant to heavy metal cadmium pollution. The research results indicate that cadmium has a significant impact on the germination status of some combinations of seeds, while the impact on other combinations is relatively small, such as: Hetou a2×041-1, Hetou a2×360-3, and Yanbian-2×041-1 have high relative germination rates, with Yanbian-3×041-1 having the highest relative germination potential, Yanbian-3×041-1 having the most prominent relative germination index, and Yanbian-3×Lingchuan c1 having the highest relative vitality index. Overall, 360-3×041-1 and Hetou a2×360-3 are at a relatively high level in terms of relative germination rate, relative germination index, and relative vitality index, while Yanbian-2×041-1 and Yanbian-3×041 are at a relatively high level. The three indicators of relative germination potential, relative germination index, and relative vitality index are all at a relatively high level, indicating that they are relatively less affected by cadmium. According to the analysis of membership functions, the average value of the membership function for combinations 360-3×041-1 is the highest, followed by Yanbian-3×041-1, Hetou a2×360-3, Yanbian-2×041-1, Yanbian-4×Lingchuan c1, Yanbian-3×Lingchuan c1, and Hetou a2×041-1. The average value of the membership function is above 0.70, indicating good growth status and good Cd tolerance. Therefore, seven pumpkin hybrid combinations with strong Cd tolerance were finally selected.