| The problem of cadmium(Cd)pollution in soil has become one of the most concerned issues.Cd not only inhibits the normal growth of plants,leading to excessive Cd content in agricultural products,but also threatens human health through the food chain.Cucumber(Cucumis sativaus L.)is a vegetable commonly eaten in daily life.It is easy to accumulate Cd in Cd polluted environment.Therefore,improving the nutrition and safety quality of cucumber is the precondition to ensure people to eat it.At present,grafting technology is commonly used in production to improve the resistance of cucumber,while pumpkins is commonly used rootstocks for cucumbers grafting,but the grafting effect with different pumpkins as rootstock is different.Therefore,in this study,we selected 5 kinds of pumpkins with strong Cd tolerance and weak accumulation ability as rootstocks,and 3 kinds of cucumbers(’Chiyu 601’,’Lvguan A8’,’Shengyou 68’)as scions to investigate the mitigation effect of grafting on Cd accumulation in cucumber under Cd stress,and further explored the main reason of the mitigation effect.The main results as follows:(1)Under Cd stress,the seed vigor index of ’Jinyou 108’ was the hightest,reaching 84.76%.The seedlings grow well,and the MDA content was no significantly difference compared with control,and the tolerance was stronger.Moreover,the Cd content in shoot and translocation factor(TF)were more significantly lower than other pumpkins,and the comprehensive membership function ranked first.The seed activity of ’Yemu Yixiong’ and ’Xinli No.3’ were higher,and the seedlings grow better,and MDA content increased slightly.Moreover,the Cd content in shoot and TF were small,and the comprehensive membership function ranked second.The Cd tolerance and absorption and transport ability of ’Qingjia Zhenjia’ and ’Kangxian No.1’ were in the middle.These results demonstrated that the tolerance of ’Jinyou 108’,’Yemu Yixiong’,’Xinli No.3’,’Qingjia Zhenjia’,’Kangxian No.1’ were stronger,and the absorb transfer ability were weak than other pumpkins,so they could be used as grafting rootstocks.(2)Under Cd stress,we used 5 kinds of pumpkin with stronger tolerance and weak absorption and transport ability to graft 3 kinds of cucumber,Cd content in cucumber fruits were significantly decreased.When ?Jinyou 108‘ and ’Yemu Yixiong’ were used as the rootstocks,the biomass of cucumber was more significantly higher than control and other grafted cucumbers,and Cd content in the fruit decreased within the safe standard range.At the same time,Vc and soluble sugar contents in fruits were more significantly higher than control and other grafted cucumbers,and the nutritional quality were higher and the grafting effect was remarkable.Whereas,when used ’Xinli No.3’,’Qingjia Zhenjia’ and ’Kangxian No.1’ as rootstocks,the Cd content in cucumber fruit decreased slightly,the mitigation effect was general.(3)Under Cd stress,when used ’Jinyou 108’ and ’Yemu Yixiong’ as rootstocks and cucumber as scions,the shoot biomass of grafted seedlings was more significantly higher than cucumber self-grafted seedlings and cucumber self-root seedlings.The Cd content in grafted cucumber roots was more significantly higher than self-grafted cucumber and self-root cucumber,but the Cd content in scion was more significantly lower,which decreased 36.37%~70.32% and 27.05%~ 69.36%,respectively.Grafting has a significant mitigation effect on Cd accumulation in Cucumber shoots.It was proved that the main factor of alleviating the Cd accumulation in cucumber comes from the Cd tolerance and transport ability of rootstock.In summary,’Jinyou 108’,’Yemu Yixiong’,’Xinli NO.3’,’Qingjia Zhenjia’,’Kangxian NO.1’ had strong Cd tolerance and weak absorption transport ability.When used these 5 kinds of pumpkins as rootstocks,the Cd accumulation in cucumber fruit was alleviated,and among them,’Jinyou 108’,’Yemu Yixiong’ had the most significant mitigation effect.The main factor of alleviating the Cd accumulation in cucumber was the Cd tolerance and transport ability of rootstock. |
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