Boron (B) is an essential trace element that plays a vital role in metabolic and physiological functions of higher plants. The adequate supply of B is important for plant growth and development. Grafting is a technique used to improve the ion uptake and plant growth. In this study, a commercial watermelon cultivar “Zaojia 8424” [Citrullus lanatus (Thunb.) Matsum. and Nakai.] was grafted onto pumpkin (Cucurbita maxima × Cucurbita moschata) rootstock cv. “Qingyan Zhenmu No.1” with an aim to investigate the response of grafted plants to different levels of B supply (0.25 μM, 25 μM and 75 μM B) in the nutrient solution. Self-grafted watermelon plants were used as control. Pumpkin rootstock improved the plant growth, chlorophyll and carotenoid contents, photosynthetic assimilation, stomatal conductance, transpiration rate, B accumulation and up-regulated the expression of NIP5;1, NIP6;1 and B transporter (BOR2, BOR4) genes in the roots and leaves at 25 μM B compared with self-grafted watermelon plants. Moreover, pumpkin rootstock reduced the oxidative stress and cell damage by reducing H₂O₂ and MDA contents, and down-regulating the expression of PDCD2-1, PDCD2-2 genes. Moreover, it enhanced the antioxidant activity of watermelon by up-regulating the expression of SOD1, SOD2, CAT2-1, and CAT2-2 genes. Based on these observations, we concluded that pumpkin rootstock has ability to improve the plant growth of watermelon by enhancing the B uptake. This study may help adjust the B concentration in the nutrient medium for watermelon production where pumpkin grafted plants are utilized.

硼（B）是必需的微量元素，在高等植物的代谢和生理功能中起着至关重要的作用。硼的充足供应对于植物生长和发育很重要。嫁接是一种用于改善离子吸收和植物生长的技术。在这项研究中，商业西瓜品种“ Zaojia 8424” [ Citrullus lanatus（Thunb。）Matsum。和中井。]接枝到南瓜（笋瓜 × 南瓜）砧木简历。“青岩真木1号”旨在研究嫁接植物对营养液中不同水平的B供应（0.25μM，25μM和75μMB）的响应。自移植的西瓜植物用作对照。南瓜砧木改善了植物的生长，叶绿素和类胡萝卜素含量，光合同化，气孔导度，蒸腾速率，B积累，并上调了根和茎中NIP5; 1，NIP6; 1和B转运蛋白（BOR2，BOR4）的表达。与自移植的西瓜植物相比，叶子的叶片浓度为25μMB。此外，南瓜砧木通过降低H ₂ O ₂和MDA含量，并下调H.O2的表达来降低氧化应激和细胞损伤。PDCD2-1，PDCD2-2基因。此外，它通过上调SOD1，SOD2，CAT2-1和CAT2-2基因的表达来增强西瓜的抗氧化活性。基于这些观察，我们得出结论，南瓜砧木具有通过增加B吸收来改善西瓜植物生长的能力。这项研究可能有助于调整利用南瓜嫁接植物生产西瓜的营养培养基中的B浓度。