修剪强度对锥栗冠层光照分布与产量及品质的影响

Effect of different pruning intensity on the canopy light distribution and yield and quality in Castanea henryi

【目的】研究锥栗不同修剪强度的冠层内相对光照强度分布与果实产量及品质特点,探究锥栗结果期适宜的修剪强度。【方法】以7 a生‘华栗3号’锥栗为试材,应用树冠分格方法,测定了锥栗不同修剪强度冠层内的相对光照强度分布、单株产量和果实品质等指标。【结果】重修剪、中修剪和轻修剪与对照相比均明显改善树冠内的光照条件,重修剪、中修剪、轻修剪冠层内相对光照强度大于30%的分别占86.11%、80.56%和75%;不同修剪强度处理中,中修剪单株产量最高,为10.25 kg,其次是轻修剪和重修剪,分别为9.29 kg和9.40 kg,而对照产量最少,为8.47 kg;重修剪在树冠中层和上层的单粒质量和淀粉含量显著高于轻修剪和对照,且含水量显著低于轻修剪和对照,中修剪和重修剪的可溶性糖和还原性糖含量显著高于轻修剪和对照。【结论】综合产量和品质两方面分析,中修剪为锥栗结果期较理想的修剪强度。

【Objective】Fruit yield and quality has a close relationship with light exposure of canopy, and improving light conditions of canopy is one of the important preconditions for fruit quality improvement.Reasonable pruning can improve light conditions of the tree canopy, which is crucial for the balance between vegetative growth and reproductive growth and for a high and stable productivity of the orchard. The current study examined the effects of different pruning intensities in Castanea henryi on the distribution of light in the canopy and fruit yield and quality, with an aim to find appropriate pruning intensity for the crop.【Methods】The experiment was carried out with a randomized block design. Pruning was conducted in the middle of December 2014 on 7-year-old trees of C. henryi cv. Huali 3. Four levels of pruning intensity were set up：（1） light pruning（15% clip）,（2） medium pruning（30% clip）,（3） heavy pruning（45%clip） and（4） no pruning（CK）. The data collected were processed using Microsoft Excel 2003, SPSS19.0and Origin Pro 8.5 mapping. On sunny days in July and August in 2015, the tree crown was divided into50 cm by 50 cm by 50 cm cubes with bamboo poles. The crown height was divided into three layers, the lower（from the ground〈1.5 m）, middle（1.5-3.0 m from the ground） and the upper（from the ground〉3.0m） layers, and in the horizontal direction, the canopy was divided into the inner（ 〈1.0 m from the trunk）and peripheral（〉1.0 m from the trunk） parts. A TES-1335 digital light meter was used to measure thelight intensities at the centers of the cubes at different positions, and at the same time full light intensity above the canopy was read, the ratio of light intensity at each position to the full light intensity was regarded as the relative light intensity of that position in the canopy. In the middle of September 2015, fruit from each position were harvested, counted and weighed separately. Single grain weight was the total weight of nuts divided by total number of nuts. Yield per tree was the average weight of nuts harvested from the trees. Water content of fruit was measured directly using drying method, soluble sugar and starch contents using anthrone method, and reducing sugar content using 3, 5-2 nitro salicylic acid method.【Results】Heavy pruning, medium pruning and light pruning significantly improved the light conditions in the crown compared with the control. In the vertical direction, the relative light intensity from the upper to the lower layers gradually reduced. In light pruning, medium pruning and heavy pruning treatments and in the control, the canopy volume with relative light intensity lower than 30% accounted for 25%, 19.44%,13.89%and 29.17% of the total canopy volume, respectively; the canopy volume with a relative light intensity in the range of 30%-80% made up 47.22%, 48.62%, 50% and 48.61%, respectively; the canopy volume with a relative light intensity higher than 80% accounted for 27.78%, 31.94%, 36.11% and 22.22%, respectively. Light pruning, medium pruning and heavy pruning treatments had a invalid canopy volume with a relative light intensity of 30% was significantly lower than the control, while their＂high-light＂volume with a relative light intensity greater than 80% was significantly greater than that in the control. The distribution of the fruit in the canopy and the distribution of relative light intensity were in high consistency. The medium pruning treatment generated the highest yield in the upper and the middle levels, which was 4.82 kg and 3.47 kg respectively and significantly higher than in the other treatments. Yield per tree had significant difference among treatment. The highest yield per tree, 10.25 kg, was found in the medium pruning treatment, followed by light pruning（9.29 kg） and heavy pruning（9.40 kg）, and the control had the lowest productivity（8.47 kg per tree）. The fruit quality reflected by starch content and soluble sugar and reducing sugar contents was better in the upper canopy in the lower canopy, but fruit water content displayed an opposite trend. Therefore, fruit quality had a close correlation with the relative light intensity. With the increase of pruning intensity, the fruit quality increased significantly. Heavy pruning resulted in a significantly better fruit quality and higher starch and sugar contents in fruit in the middle and upper canopy but a significantly lower moisture content than light pruning and control.【Conclusion】Based on the analysis of both yield and quality, medium pruning for C. henryi was the ideal pruning intensity.