树形对龙安柚叶片生理状况及果实品质的影响

以自然圆头形、开心形和Y字形的5年生龙安柚为试材,测定了营养枝和结果枝叶片的水分、营养元素的质量分数和光合特性等生理指标及果实品质,并分析了各项生理指标与果实品质的相关性.结果表明:(1)3种树形营养枝叶片的干物质的质量分数、叶面积、水分利用效率和净光合速率均高于结果枝,且3种树形的这几项指标从大到小的顺序为:Y字形、开心形、自然圆头形.而且自然圆头形的蒸腾速率最大,为3.18 mmol/m~2·s.(2)开心形叶片的大量元素(N,P,Ca,Mg)的质量分数较其他两种树形高,且均表现为营养枝高于结果枝,其中营养枝叶片N,P,Ca,Mg的质量分数分别为2.45%,0.11%,6.54%,0.40%;Y字形和圆头形叶片微量元素(Fe,Mn,Zn,Cu,B)的质量分数高于开心形,其中Mn,Cu的质量分数为营养枝显著高于结果枝,但Fe,Zn,B的质量分数为营养枝显著低于结果枝.(3)Y字形和开心形的果实色泽、单果质量和果形指数均优于自然圆头形,其中开心形单果质量是自然圆头形的1.12倍;Y字形可溶性固形物的质量分数(10.33%)、Vc质量比(0.618 mg/g)、还原糖的质量分数(3.81%)、固酸比(16.78%)、糖酸比(13.54%)均显著高于其他树形,而可滴定酸、转化糖、蔗糖和总糖的质量分数差异不具有统计学意义.(4)营养枝、结果枝叶片的含水量、叶片干物质质量比、光合特性、营养元素的质量分数对果实品质均有影响,其中营养枝和结果枝的净光合速率与可溶性固形物的质量分数、Vc质量比、总糖的质量分数、固酸比、糖酸比均呈正相关.

Impact of Tree Training Systems on the Physiological Characteristics of Leaves on Different Branches of Citrus grandis var. Long' anyou and on Its Fruit Quality

In this paper, Citrus grandis var. Long'' anyou trees with different crowns formed by three kinds of training system, i. e. natural round shape, open center shape and Y-shape, were used as experimental materials, the water content, nutrient contents and photosynthetic physiological characteristics of the leaves on their vegetative shoots and bearing branches were compared, and the correlation of the above-mentioned parameters with their fruit quality was analyzed. The results showed that the leaf dry matter content (LDMC), leaf area (LA), water use efficiency (WUE) and net photosynthesis rate (Pn) of the vegetative shoots were significantly higher than those of the bearing branches, and there was a similar tendency in all the three kinds of training system. These parameters were in the order of Y-shape > open center shape > natural round shape. The leaves on the vegetative shoots of the round-crowned trees had the highest transpiration rate (Tr=3.18 mmol/m2·s). The leaves of the open-centered trees had higher contents of the major nutrient elements N, P, Ca and Mg than those of the other two training systems, and the four elements were higher in the vegetative shoot leaves than in the bearing branch leaves of all the three training systems. The contents of trace elements (Fe, Mn, Zn, Cu and B) were the lowest in the leaves of the trees with an open-centered crown. Moreover, Fe, Zn and B in the bearing branch leaves were significantly more than those in the vegetative shoot leaves, but the reverse was true of Mn and Cu. The fruit color, fruit weight and fruit shape index of the Y-shaped trees and the open-centered trees were better than those of the natural round-shaped trees. Moreover, the fruit weight of the open-centered trees was 1.12 times that of the natural round-shaped trees. The Y-shaped trees had significantly higher soluble solids (10.33%), vitamin C (0.618 mg/g), reducing sugar (3.81%), solid/acid ratio (16.78%) and sugar/acid ratio (13.54%) than the other two training systems, but titratable acid, invert sugar, sucrose and total sugar showed no significant difference among the three. Correlation analysis showed that the measured physiological parameters influenced the fruit quality. Net photosynthesis rate (Pn) was positively correlated with soluble solids, vitamin C, total sugar, solid/acid ratio and sugar/acid ratio.