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泛采用的一年两熟生长模式——早生长季（EGS，Early Growing Season）与晚生长季（LGS，Late Growing Season），探究其对果实品质性状的影响，涉及外观、硬度、总可溶性固形物、糖类、总酚含量及抗氧化活性等多项指标。试验选用两个西瓜[Citrullus lanatus (Thunb.) Matsum. & Nakai]品种‘Anthem F1’与‘Crimstar F1’作为接穗（scion）；以两个笋瓜×南瓜（C. maxima × C. moschata）杂交品种‘Shintoza F90’与‘Obez’，以及一个葫芦[Lagenaria siceraria]砧木（rootstock）品种‘Macis’作为砧木；并以自根苗与自嫁接苗作为对照组。相较于晚生长季（LGS），两个供试西瓜品种在早生长季（EGS）下的果实形状指数、果皮厚度、果汁pH值、色泽色相值及葡萄糖含量均显著降低。但另一方面，‘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。两个供试品种的总酚含量均不受接穗/砧木组合与生长季的影响。当采用特定的砧木/接穗组合与生长季时，多数果实品质性状均得到改善，且这类组合的适配效果会因品种不同而存在差异。因此，针对由生态环境与生长周期所构建的各类生长条件，评估并筛选适配的接穗与砧木组合，对保障果实高品质具有重要意义。