钙镁配施对琯溪蜜柚果实产量和品质及钙镁养分的影响

为探究钙镁配施对琯溪蜜柚果实产量品质及钙镁养分的影响，以福建平和15年树龄酸柚砧白肉琯溪蜜柚为试验材料，设置钙肥（CaO）、镁肥（MgO）施用总量为1.50 kg/株，而钙、镁配比不同（ 0:0，9:1，8:2，7:3，6:4）的5个处理，连续进行2年（2017-2018年）的试验。结果表明，琯溪蜜柚叶片Ca含量在果实生长期呈逐渐上升的变化规律，果实成熟期达最大值，叶片Mg含量的变化趋势与Ca相反，在果实膨大期出现最低值；连续钙镁配施既能保证果实对Ca、Mg的吸收，又能缓解叶片缺乏Ca、Mg。增加钙肥比例显著降低果实可滴定酸，提高固酸比、Vc和出汁率，而增加镁肥比例显著降低果实可溶性固形物，但提高果实Vc含量、可食率和出汁率。综合果实产量品质等指标，推荐成年白肉琯溪蜜柚钙肥（CaO）、镁肥（MgO）施用量分别为1.05 ~1.27 kg/株和0.15~0.33 kg/株。

Effects of combined application of Calcium and Magnesium on the yield, quality and Calcium and Magnesium nutrients of Guanxi pomelo

Five different calcium and magnesium combined fertilizer treatments (CaO: MgO 0:0, 9:1, 8:2, 7:3, 6:4) were set up in the 15-year-old trees with white flesh Guanxi pomelo in Pinghe area to explore the effect of combined application of calcium and magnesium on the fruit yield, quality and calcium and magnesium nutrients of Guanxi pomelo, and the total amount of CaO and MgO fertilizer application was 1.50 kg/plant, applied continuously for two years (2017-2018). The Calcium(Ca) content in the leaves of Guanxi pomelo showed a gradual increase in the fruit growth and development cycle, and reached the maximum in the fruit ripening period. The trend of Magnesium(Mg) content in leaves was opposite to Ca, the lowest value appeared in the fruit expansion stage. The continuous combined application of calcium and magnesium can not only ensure the absorption of Ca and Mg in the fruit, but also alleviate the lack of Ca and Mg in the leaves. Increasing the proportion of calcium fertilizer significantly reduced the titratable acid(TA) of fruit and increased the ratio of solid acid, Vc and juice yield, while increasing the proportion of magnesium fertilizer significantly decreased the soluble solids(TSS) of fruit, but increased the Vc, edible rate(ER) and juice yield of fruit. Taking into account the indicators of fruit yield and quality, the recommended application rates of calcium fertilizer (CaO) and magnesium fertilizer (MgO) are 1.05-1.27 kg/plant and 0.15-0.33 kg/plant for 15-year-old white-fleshed Guanxi pomelo, respectively.