| ‘Shatangju’(Citrus reticulata Blanco cv. Shatangju) is a mandarin cultivar with the largest cultivation areas in Guangdong, even in southern China. and its yield, fruit quality, resistance and other horticulture traits are given significant importance by the screening of appropriate rootstocks. As the foundation of the grafted fruit trees, rootstocks determine the absorption and transportation functions of plants to some extent, thus affecting the growth aboveground. Therefore, the researches on root architecture of different rootstocks are of great significance for evaluation and selection of rootstocks, as well as for the production development of ‘Shatangju’ mandarin in southern China.Eight typical citrus rootstocks, including Rough lemom(Citrus jambhiri Lush)、Goutou orange(Citrus aurantium L. cv. Goutou Cheng)、Canton lemon(Citrus limonia Osbeck)、Red tangerine(Citrus reticulate Blanco cv. Red tangerine)、Sunki mandarin(Citrus reticulate Blanco)、Fragrant orange(Citrus junons Sieb. ex. Tanaka)、Carrizo citrange(hybird of Citrus sinensis Osbeck. ×Poncirus trifoliate Raf)and Trifoliate orange [Poncirus trifoliata(L.) Raf] were observed in the paper. The whole plant was excavated and the image analysis method was applied to measure the morphological characteristic and architecture parameters of different rootstocks and observe the growth situation of root hair of different rootstocks. At the same time,-the grafted trees were planted to compare the early performances of ‘Shatangju’ grafted with different rootstocks, with the purpose to provide theoretical and application basis for the use of citrus rootstock in production. As indicated from the research:1. Under the same growth period, Fragrant orange, Goutou orange and Trifoliate orange were the most three vigorous growth root system, enjoyed the larger total root length, total root surface area, total root volume and root mean diameter, higher number and density were presented on their lateral roots.2. Under the same growth conditions, relatively large topological indices was presented by the root of Carrizo citrange, whose root branching pattern was close to a herringbone branching; while relatively smaller topological index was displayed by Rough lemon, Goutou orange, Canton lemon, Sunki mandarin and Fragrant orange, whose root branching pattern was close to a Dichotomous braching. Whereas there were no significant differences between root fractal dimension, which suggested there was homoplasy among the root branching of eight citrus rootstocks.3. Root hairs was observed on the citrus rootstocks root system besides the rough lemon. The shapes of root hair was mainly in finger-shaped or half-finger-shaped.The distribution of root hair was massive rosette or random growth.The root hair density of Canton lemon, Fragrant orange and Trifoliate orange showed significant differences on different root segment, and the maximum density values of all seven rootstocks were appeared in the segments of 1-2cm or 2-3cm away from the root tips.4. It shows a significant or non-significant effect on growth, florescence, yield, fruit quality and other aspect while Shatangju grafted on different rootstocks. Grafted onto Trifoliate orange, among all rootstocks, enjoyed the highest height and largest tree crown, but the poor flavor with minmum sugar-acid ratio, the fruit was allowed to be enlarged significantly. While graftec onto Goutou orange, the fruit flavor was improved with a significant higher sugar-acid ratio and TSS-Acid ratio compared to the control group. Grafted on Fragrant orange plant had the most dwarf height and smallest tree crown, the fruit yield and fruit qulity were reduced significantly either. |
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