The effectiveness of growth cycles on improving fruit quality for grafted watermelon combinations

Abstract Two growth cycles per year, i.e., for early growing season (EGS) and late growing season (LGS) production, both of which are widely preferred in temperate climates, have been investigated for their effects on fruit quality attributes such as appearance; firmness; the content of total soluble solids, sugars, and total phenol; and antioxidant activity. Two watermelon [Citrullus lanatus (Thunb.) Matsum and Nakai] cultivars (cv. 'Anthem F1' and cv. 'Crimstar F1') were used as scion. Two C. maxima × C. moschata hybrids (cv. 'Shintoza F90' cv. 'Obez') and one Lagenaria siceraria rootstock cv. 'Macis' were used as rootstock. Self-rooted and self-grafted plants were used as controls. EGS resulted in a reduction of fruit shape index, rind thickness, juice pH, hue values, and glucose content as compared to LGS for both the cultivars. On the other hand, total soluble solids of cv. 'Crimstar', fructose of cv. 'Anthem', and the antioxidant activity of cv. 'Anthem' increased. The total phenol content was unaffected by the scion/rootstock combinations or growth seasons for both the cultivars. Most of the fruit quality attributes increased when a specific rootstock/scion combination and growth season was used and these combinations may change in relation to cultivar. It is important to evaluate and select suitable scion/rootstocks for each growth condition created by ecology and growth cycle to guarantee high fruit quality.

摘要 本研究针对温带气候下广受青睐的一年两熟栽培模式——即早生长季（Early Growing Season, EGS）与晚生长季（Late Growing Season, LGS）——展开探究，分析其对西瓜果实品质性状的影响，考察指标涵盖外观品质、果实硬度、总可溶性固形物含量、糖类物质含量、总酚含量以及抗氧化活性等。试验以两个西瓜[Citrullus lanatus (Thunb.) Matsum. & Nakai]品种‘Anthem F1’与‘Crimstar F1’作为接穗；选用两个C. maxima × C. moschata杂交品种‘Shintoza F90’、‘Obez’以及一个葫芦[Lagenaria siceraria]砧木品种‘Macis’作为砧木，并设置自根苗与自嫁接苗作为对照处理。相较于晚生长季，早生长季下两个供试品种的果形指数、果皮厚度、果汁pH值、色泽色调值及葡萄糖含量均显著降低。反之，‘Crimstar F1’的总可溶性固形物含量、‘Anthem F1’的果糖含量，以及‘Anthem F1’的抗氧化活性均有所提升。而两个供试品种的总酚含量均不受接穗/砧木组合及生长季的影响。当采用特定的接穗/砧木组合与生长季搭配时，多数果实品质性状可得到改善，且这类组合的效果因品种而异。针对由生态环境与生长周期所构建的各类栽培条件，评估并筛选适配的接穗与砧木，对保障高品质果实产出具有重要意义。