Fruit yield and quality response of Newhall navel orange to different irrigation regimes and ground cover in Chongqing Three Gorges Reservoir area
2018
Yang, Qiong | Wang, Ya | Jia, Xue-mei | Zheng, Yong-qiang | He, Shao-lan | Deng, Lie | Ma, Yan-yan | Xie, Rang-jin | Yi, Shi-lai | Lv, Qiang
In order to reduce unwanted negative effect of frequent rainfall in spring and high-temperature in summer on fruit yield and quality of Newhall navel orange trees in Chongqing Three-Gorges Reservoir area. In this study, the influence of Tyvek® nonwoven materials ground cover (TC) and with different irrigation density 110% (ID110), 60% (ID60), and 0 (ID0) of the local evapotranspiration (ETc) on yield and fruit quality were evaluated during three consecutive years (2015–2017) in a commercial Newhall navel orange drip irrigated orchard. During spring frequent rainfall period, all TC treatments had a significant higher in leaf sucrose content and leaf starch content during flower bloom period due to their significantly increased the leaf ACO2 exchange parameter compared to CK group. As a result, the highest in the number of fruit bearing (FBN) was obtained in TC+ID60 group due to its 84.6% and 13.5% higher the total flower number (TFN) than CK and TC+ID110 groups, respectively. However, the TC+ID110 and TC+ID0 groups had a significantly lower FBN due to their significantly 38.3% and 19.9% rate of dropped flowers (FLDR) compared to TC+ID60 group. During summer high-temperature period, the leaf water potential significantly decreased in order: TC+ID110, TC+ID60 and CK, TC+ID0, which resulted in the significant higher ACO2 and transpiration rate in TC+ID110 and TC+ID60 groups, and significant lower ACO2 and transpiration rate in TC+ID0 group. Consequently, there was a significant increase of total soluble solids, titratable acid, vitamin C in fruit internal quality and “a”, “b”, “a/b” value in fruit external quality, and a significant decrease of juice yield in fruit internal quality and fruit shape index, and weight per fruit with increasing water stress as compared to TC+ID110 group. In conclusion, TC+ID60 treatment can reduce the negative effect of frequent rainfall spring and high summer temperatures and improve the fruit yield and quality of Newhall navel oranges.
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