A New Grafting Method for Watermelon to Inhibit Rootstock Regrowth and Enhance Scion Growth

Mu Xiong,Xiaohu Fu,Yuan Huang,Changjin Liu,Zhilong Bie,Chongran Feng,Weiguo Lin,Xiangshuai Wu

doi:10.3390/agriculture11090812

Abstract

Grafting is a widely used technique in watermelon (Citrullus lanatus) production. However, cost of grafted seedlings is generally high as a result of intensive labor inputs for propagation using traditional grafting methods such as the manual removal of rootstock regrowth. This study developed a new grafting tool to physically remove the epidermis of pumpkin (C. maxima × C. moschata) and bottle gourd (Lagenaria siceraria) rootstock cotyledon base during grafting; we called this a new grafting method. Compared with the traditional grafting, the new grafting method significantly decreased the pumpkin rootstock regrowth rate from 100% to 8% in hole insertion and 2% in one cotyledon grafting, respectively. These attenuated rates for bottle gourd rootstock regrowth were 23% and 9% in hole insertion and one cotyledon grafting, respectively. The scion dry weights of new hole insertion and one cotyledon grafting were increased by 78% and 74% when pumpkin was used as rootstock as compared with traditional grafting without regrown rootstock removal, while the respective values were 33% and 17% in bottle gourd rootstock grafted plants. In addition, the time used for the new hole insertion grafting method to physically remove the epidermis of pumpkin rootstock cotyledon base was significantly shorter than the time required to remove the rootstock regrowth manually three times in the traditional grafting (4.2 s/plant vs. 9.3 s/plant). Similar results were also observed in the new one cotyledon grafting (4.2 s/plant vs. 8.8 s/plant). Taken together, this study presents a new method in watermelon grafting to reduce rootstock regrowth, therefore benefiting both scion growth and plant management, thus the development of this new method is clearly useful in watermelon production.

Highlights

There was no significant difference on the graft survival rate between the new grafting method and the traditional grafting method for pumpkin and bottle gourd rootstocks, for both the hole insertion and one cotyledon grafting methods (Figure 3a–d)
8% in pumpkin hole insertion using the new method as compared with traditional methods, and the value was decreased from 100% to 2% in one cotyledon grafting (Figure 5a)
The rootstock regrowth rate was decreased from 100% to 23% using hole insertion and from 100% to 9% using one cotyledon grafting (Figure 5b)

Summary

Introduction

Grafting plants permits us to select and combine different rootstocks and scions for disease resistance, abiotic stress tolerance, and enhanced yield traits [1,2]. Watermelon is an important cucurbit crop; the world production of watermelon was 101 million tons, and the area harvested was 3.09 million ha hectares in 2019. China is the world’s largest producer of watermelon, where the watermelon production was 61 million tons, whereas the planting area was 1.47 million ha in 2019 Grafting is a commonly used technique in watermelon production.

Objectives

Methods

Results

Discussion

Conclusion