| Grafting technology is widely used in cucurbit crop production,but the problem of rootstock regrowth exists,there is a lack of practical and effective solutions.In this study,watermelon,melon and cucumber were used as scions,pumpkin and bottle gourd were used as rootstocks for grafting,through physical and chemical methods to optimize the grafting process and thus inhibit rootstock regrowth,in order to provide guidance for the production of grafted cucurbit seedlings.The results are as follows:1.Development of a new grafting tool,which consists of a file and a grafting needle for frictional removal of the epidermis at the base of rootstock cotyledons and grafting perforation,and combined with existing grafting methods to form a less rootstock regrowth grafting method.In watermelon,melon and cucumber grafting,the survival rate of the less rootstock regrowth grafting method ranged from 82% to 100%,with no significant difference compared with the traditional grafting method.The less rootstock regrowth grafting method greatly inhibits the rootstock regrowth,the regrowth rate is only 2% to 24%,which is significantly lower than the traditional grafting method(82%～100%),in one-cotyledon grafting,the regrown leaf area on the rootstock of the less rootstock regrowth grafting method is significantly smaller than that of the traditional grafting method.The scion height,stem,fresh weight,dry weight and leaf area of the less rootstock regrowth grafting method are generally higher than those of the traditional grafting method,the leaf area was increased by 5% to 25% and enhancing the growth of the scions.The less rootstock regrowth grafting method had no adverse effects on rootstock growth,it was able to enhance rootstock growth and increase rootstock biomass in watermelon/pumpkin hole-insertion grafting,melon/pumpkin one-cotyledon grafting and cucumber/pumpkin one-cotyledon grafting.Statistics on grafting time and rootstock regrowth removal time show that the less rootstock regrowth grafting method produces one grafted seedling in 5 s less time than traditional grafting methods,considering the growth of the grafted seedlings and the labour input,this less rootstock regrowth grafting method is suitable for application in practice.2.Spraying of rootstocks with exogenous indole-3-acetic acid(IAA)and Lovastatin(Lov)solutions significantly inhibited the regrowth of rootstock,IAA treatment delays rootstock regrowth by 2 d,maximum at 9 d after grafting with a regrowth rate of 87%.Lov treatment can cause rootstock regrowth to occur followed by wilting,resulting in a trend of increasing and then decreasing rootstock regrowth rates,with a final regrowth rate of only 4%.The mixture of IAA and Lov worked as a combination of both substances and the regrowth rate was very low and stable at 3.4%.However,IAA can cause damage to the rootstock,causing severe bending of the rootstock hypocotyl,affecting the grafting operation and survival rate,making the application difficult to promote,and we have only conducted seedling quality evaluation trials with different concentrations of Lov.Treatment with 1 mM Lov solution had no significant effect on the survival of grafted seedlings.The treatments of 1 mM significantly reduced the regrowth rate of rootstocks compared to the control,and the 1 mM treatment significantly reduced the biomass of rootstock regrowth.The treatment with 1 mM and 0.5 mM increased the leaf area of the scion by 18% to 34%and the treatment with 1 mM increased the fresh weight of the scion by 32% to 50%,the treatment with Lov solution significantly promoted the growth of the scion and did not adversely affect the growth of rootstock.Spraying with Lov solution 24 h before grafting significantly reduces the regrowth rate of rootstocks and promotes the growth of grafted seedlings,and can be suitable for application in practice.Considering the growth of grafted seedlings and labor input,the two grafting techniques developed in this study are cost effective and have broad application prospects in practice. |
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