摘要
【目的】钾肥过量是目前苹果果皮发黄、着色不良的重要原因。拟通过田间试验,调查不同钾肥用量在氮、磷、钙、镁不同肥料配合下,对苹果果实色泽、养分元素含量及果皮色素的影响。探讨过量钾肥导致富士苹果果皮发黄的作用机制,为有效预防提供理论依据。【方法】供试树为9年生富士,八棱海棠为砧木,单株产量约60 kg。土壤为中性潮土,中等肥力。根据苹果对营养元素的吸收特性及相互作用原理,参考农民施肥习惯和前人研究结果,试验以N-P、N-P-Mg、N-P-Ca 3种肥料配合为基础,与每株0—2 000 g(0、125、250、500、1 000和2 000 g/株)的K2O配合施用,测定果实着色度、花青素、叶绿素、类胡萝卜素、果实和土壤中的主要矿质元素含量。【结果】在3种肥料配合中,果实着色度均随钾肥用量的增加呈先提高后降低的变化趋势,N-P-Mg配合果实着色度最好,N-P-Ca配合最差;果实着色最好的钾肥用量,N-P、N-P-Ca配合在250 g/株,N-P-Mg配合延迟至1 000 g/株;N-P配合中钾肥用量与果实K含量、土壤残留K含量呈显著正相关,与果实Mg含量呈极显著负相关;N-P-Mg配合中钾肥用量与果实中矿质元素含量相关性均不显著;N-P-Ca配合中钾肥用量与果实中N含量呈极显著负相关,与果实中Fe含量呈显著正相关,果实中N的均值比N-P处理高37.5%;果皮叶绿素含量随钾肥用量的增加,在N-P配合下呈先提高后降低趋势,在N-P-Mg配合下逐渐降低,而在N-P-Ca配合下呈先降低后提高趋势;果皮类胡萝卜素含量随钾肥用量增加,在N-P-Mg配合下呈先降低后提高的变化趋势,与N-P配合基本一致,而在N-P-Ca配合下基本上呈不断提高的趋势。3种配合的果皮类胡萝卜素含量均在钾肥用量最多时,达到最高,但花青素含量却最低,因此导致果皮发黄,着色不好。【结论】富士苹果着色度随钾肥用量的增加呈先提高后降低趋势;过量施钾促进了果实钾的积累,抑制了镁的吸收,导致果皮中花青素含量降低,类胡萝卜素含量提高,使果皮呈黄色着色不良;配施镁肥使果皮着色最好的K2O用量从250 g/株延迟到1 000 g/株,有效减轻了高量钾肥对苹果着色的不良影响;配施钙肥由于增加了果实中N和Fe的含量,使果皮叶绿素含量提高而花青素含量降低,对果实着色有负作用。本研究结果表明果实色泽是N、P、K、Ca、Mg、Fe、Mn几种养分元素共同作用的结果,增施某种养分时,必需注意保持与其它各元素间的平衡。
【Objective】 Potassium overdose is found to be one of the most important causes for poor coloring of apple fruit. The influence of the combination of different fertilizers (nitrogen, phosphorus, calcium and magnesium) on apple fruit coloring, nutrient content and skin pigments, was studied for the purpose of investigating the mechanism of skin yellowing of ‘Fuji’ apple fruit resulted from over-application of potassium. Hopefully, this study will provide theoretical references for effective prevention of yellowing of apple fruit skin. 【Method】 The nine-year old ‘Fuji’ apple tree grafted on Malus robuste rootstock with an average yield of about 60 kilograms per plant was used as experimental material. Neutral wet soil with medium fertility was used in the experiment. Based on the principles of uptake and interaction of different nutrient elements, fertilization of this study took reference to the fertilizing experience and results of former studies. Each apple plant was fertilized with 0, 125, 250, 500, 1 000 and 2 000 g K2O combined with constant amount of either N-P, N-P-Mg or N-P-Ca. Apple coloring degree, content of anthocyanin, chlorophyll, carotenoids, and content of major mineral elements in both fruit and soil were measured. 【Result】 In all three fertilization combination sets (N-P, N-P-Mg, and N-P-Ca), fruit coloring was firstly improved and then decreased as K2O amount increased, with best fruit coloring in N-P-Mg treatment and worst coloring in N-P-Ca treatment. In N-P and N-P-Ca treatments, 250 g K2O per plant was optimal for fruit coloring, and 1 000 g K2O per plant was optimal for N-P-Mg treatments. In N-P combinations, K2O application was significantly positively correlated with fruit K content and soil K residual while significantly negatively correlated with fruit Mg content. In N-P-Mg, there was no significant correlation between K application and content of mineral nutrients in apple fruit. In N-P-Ca combinations, fruit N content was significantly negatively correlated with K application, and fruit Fe content was significantly positively correlated with K application, with average N content 37% higher than that in N-P treatments. With the increase of K application, the content of chlorophyll in fruit skin increased first and then decreased in N-P treatments, decreased constantly in N-P-Mg treatments, and decreased first then increased in N-P-Ca treatments. With the increase of application K fertilizer, the content of carotenoid decreased first and then increased in N-P-Mg treatments, basically remained constant in N-P treatments, and constantly increased in N-P-Ca treatments. In all three combinations, the content of carotenoid reached peak with highest application of K fertilizer, but anthocyanin content was the lowest at this point, which probably caused the yellowing of fruit skin and poor coloring. 【Conclusion】 The color percent of ‘Fuji’ apple increased at first, and then decreased as the dose of potassium fertilizer added. Over application of potassium promoted absorption potassium and inhibited absorption magnesium of the trees with the concentration of anthocyanin decreasing and that of carotenoid increasing, which resulted in the fruit poor coloring. Fertilization with magnesium made optimal dose for fruit coloring from 250 g to 1 000 g per plant that alleviated the negative effects of K over-use on fruit coloring. Fertilization with calcium enhanced the concentration of N and Fe in fruit to decrease the concentration of anthocyanin and increase that of carotenoids. This study suggests that fruit coloring depends on the interaction of N, P, K, Ca, Mg, Fe, and Mn and it is especially important to keep the balance between different elements while fertilization.
出处
《中国农业科学》
CAS
CSCD
北大核心
2014年第5期946-954,共9页
Scientia Agricultura Sinica
基金
国家现代苹果产业技术体系专项经费项目(CARS-28)
烟台市科技发展计划项目(2010204)
关键词
钾肥
富士苹果
着色
影响因素
机理
potassium fertilizer
Fuji apple
coloration
impact factor
mechanism