纽荷尔脐橙高产优质的磷钾最佳配比研究

Optimum P and K ratio for high yield and good quality of ‘Newhall’ navel orange

【目的】矿质元素的均衡供应是保证柑橘优质高产的前提。研究适宜氮水平下不同磷钾配比对脐橙产量和果实品质的影响,为脐橙合理施肥提供依据。【方法】位于湖北省秭归县的脐橙磷钾配比田间定位试验始于2007年,品种为枳壳砧木纽荷尔脐橙(Citrus sinensis Osbeck),树龄为18~20年。试验采用"3414"试验方案,氮水平均为0.80 kg/(tree·a),设7个不同磷钾配比处理P_0K_2、P_1K_2、P_2K_2、P_3K_2、P_2K_0、P_2K_1、P_2K_3,P_0、P_1、P_2和P_3的施磷量依次为P_2O_5 0、0.20、0.40和0.60 kg/(tree·a),K_0、K_1、K_2和K_3施K_2O依次为0、0.25、0.50和0.75 kg/(tree·a)。于2012年(试验第5年)采集成熟期果实样品进行品质分析,并进行产量实测。【结果】1)K_2水平下,增施磷肥可以提高果实产量,其中P_2K_2处理产量为38.34 kg/tree,较P_0K_2显著提高44.6%,P_2K_2处理果实可溶性固形物和Vc含量较P_0K_2分别显著提高3.7%和14.6%;随磷肥施用量增加,果实果糖、葡萄糖、蔗糖含量均呈先增后降的变化规律,且均在P_2K_2处理达到最高,P_2K_2处理果实葡萄糖和蔗糖含量较P_0K_2分别显著提高20.8%和12.5%,果糖含量相差不显著;增施磷肥可降低果实可滴定酸和柠檬酸含量,与P_0K_2处理相比,P_1K_2和P_3K_2处理可滴定酸含量分别显著降低18.8%和14.7%,P_2K_2和P_3K_2处理柠檬酸含量分别显著降低18.8%和14.7%。2)P2水平下,P_2K_3处理产量较P_2K_0显著提高24.6%;随钾肥施用量增加,果实可溶性固形物和Vc含量先增后降,P_2K_2处理可溶性固形物和Vc含量最高,较P_2K_0处理分别显著提高13.1%和20.3%;在试验设置的钾水平范围内,增施钾肥可提高果实可溶性糖含量,P_2K_2处理果实果糖、葡萄糖和蔗糖含量较P_2K_0分别显著提高23.8%、33.2%和25.1%;P_2K_1处理果实可滴定酸和柠檬酸含量较P_2K_0有所降低,但P_2K_2处理可滴定酸含量较P_2K_0显著提高21.8%,果实柠檬酸含量相差不显著。【结论】纽荷尔脐橙在合理施氮量(N)0.80 kg/(tree·a)基础上,以果实风味最佳、产量较高为目标,推荐纽荷尔脐橙磷肥(P_2O_5)和钾肥(K_2O)施用量分别为0.41~0.46 kg/(tree·a)、0.45~0.50 kg/(tree·a),其相应的N∶P_2O_5∶K2O比例为1∶0.51~0.58∶0.56~0.63。

[Objectives]Balanced supply of mineral elements is critical to ensure high quality and yield of citrus. Combined application of nitrogen （N）, phosphorus （P） and potassium （K） rationally is significant in improving the citrus yield and quality.[Methods]The ‘Newhall’ navel orange （Citrus sinensis Osbeck） used in this study was trifoliate rootstock, the orange trees were 18-20 years old. The field experiment was conducted in Zigui County, Hubei Province since 2007. P and K fertilizer treatments were designed with ＂3414＂ pattern, as PK2, P1K2, P2K2, P3K2, P2K0, P2K1 and P2K3. The respective four P and K rates included P2O5 0, 0.20, 0.40, 0.60 kg/tree and K2O 0, 0.25, 0.50, 0.75 kg/tree each year, along with N 0.80 kg/tree each year. The fruit yield was investigated and the fruit quality was analyzed in 2012.[Results]1） The fruit yield in treatment P2K2 was 38.34 kg/tree, significantly higher by 44.6% than that in treatment P0K2 （P 〈 0.05）. The total soluble solid, Vc, glucose and sucrose contents of citrus fruit in P2K2 treatment were significantly increased by 3.7%, 14.6%, 20.8% and 12.5%, respectively, over the treatment of P0K2. P fertilizer application did not significantly affect fruit fructose contents. In P1K2, P2K2 and P3K2, the titratable acid and citric acid contents of citrus were lower than P0K2. Compared to P0K2, the titratable acid contents of P1K2 and P3K2 were significantly decreased by were 18.8% and 14.7%, respectively, while the citric acid contents of P2K2 and P3K2 significantly decreased by 18.8% and 14.7%. 2） The fruit yield of P2K3 was significantly increased by 24.6%, compared to P2K0. As the application rate of K fertilizer increased, the total soluble solid and Vc contents increased initially and then decreased. P2K2 treatment resulted in the highest total soluble solid and Vc contents, which were 13.1% and 20.3% higher than those of P2K0, respectively. Within the tested K levels, application of K fertilizer could increase the content of soluble sugar content in fruit. Fructose, glucose and sucrose contents in P2K2 were significantly increased by 23.8%, 33.2% and 25.1%, respectively, compared to P2K0. In P2K1 treatment, the fruit titratable acid and citric acid content of citrus were decreased compared to P2K0, while titratable acid of P2K2 treatment increased by 21.8% compared to P2K0. There was no significant difference in fruit citric acid contents.[Conclusions]The optimum P and K application rates were P2O5 0.41-0.46 kg/（tree·a） and K2O 0.45-0.50 kg/（tree·a） along with N 0.80 kg/（tree·a） with N：P2O5：K2O ratio of 1：0.51-0.58：0.56-0.63 for high yield and high quality of ‘Newhall’ navel orange.