Comprehensive evaluation of labor-saving tree shapes and varieties of pear based on the Affiliation Function and VIKOR methods

【Objective】Labor-saving and simplified cultivation is an inevitable trend for fruit tree development. The tree shapes and varieties directly affect the establishment of the orchards and the production outcome. The production process is characterised by the quality of the varieties and the efficacy of the tree shapes. However, discrepancies in the process may result in suboptimal orchards establishment, and instances of failure are not uncommon. Therefore, the establishment of a system for the evaluation of tree shape and variety is imperative. The double arm parallel trellis cultivation system offers significant advantages in fruit quality, labor savings, and mechanization, making it one of the most rapidly adopted pear cultivation models in the middle and lower reaches of the Yangtze River. This study aims to fill existing literature gaps by systematically identifying pear varieties suitable for double-arm parallel trellis cultivation. Research indicates no prior variety screening studies specifically targeting this cultivation model. To identify superior varieties suitable for labor-saving, simplified cultivation under dou-ble-arm parallel trellis systems, matching high-quality varieties with labor-saving tree forms is crucial. 【Methods】In the present study, 17 varieties of pear orchards cultivated with the double arm parallel trellis cultivation mode in the middle and lower reaches of Yangtze River production areas were selected as the primary research objects. The differences in growth, fruiting characteristics and fruit quality indexes of different varieties were investigated. Subsequently, the growth and fruit quality of different varieties were evaluated under the double arm parallel trellis cultivation mode using the affiliation function method and VIKOR method. In the context of optimal tree growth and fruiting conditions, shorter new shoot length, reduced crown width (both east-west and north-south), decreased tree height, and a later onset of fruiting were more conducive to the management of orchard cultivation in a simplified manner. The hypothesis that reduced chew resistance is indicative of superior taste is one of that merits further investigation. Therefore, a comprehensive evaluation was conducted by the reciprocals of the aforementioned indicators. To ensure the accuracy of the assessment results, we employed the correlation function method to select 20 comprehensive evaluation indicators, including 1/new shoot length, germination rate, branching capacity, 1/canopy width (east-west), 1/canopy width (north-south), number of fruiting branches, short and medium branches ratio, long branches ratio, 1/early fruiting, yield, single fruit weight, total soluble solids, titratable acid, total soluble solids/titratable acid content (TSS/TA), vitamin C content, flesh firmness, flesh fineness, reversibility, 1/chewability and brittleness.【Results】It is evident that various varieties display marked variations in growth characteristics when cultivated within the double arm parallel trellis system, with the coefficient of variation for the parameters of long shoot ratio, branching capacity, yield, and number of fruiting shoot clusters all exceeding 35%. The coefficients of variation of eight indexes, namely branching ability, long branching ratio, yield, number of fruiting branches, TSS/TA, titratable acid content, flesh fineness and chewability, were large and differentiated among different varieties under the double arm parallel trellis cultivation mode. The utilisation of the affiliation function method resulted in a comprehensive evaluation value greater than 0.70. The four pear cultivars identified were Housui, Wonhwang, Cuiguan and Yulü. The Eli No. 2 evaluation yielded a value of 0.691, which was in close proximity to 0.70. A comprehensive evaluation value below 0.6 was observed in four pear varieties: Zaojinsu, Zhongli No. 1, Zhongli No. 4, and Zaosumi. In addition, the aforementioned five varieties were to be considered the most highly ranked. The application of the VIKOR method to the evaluation process indicated that the weight value assigned to early fruiting is 19.3%, representing the largest proportion. In contrast, the weight allocated to the ratio of short and medium branches was the smallest, at 2.3%. The remaining indicators fell within the intermediate range. The top five in the comprehensive ranking were Housui, Wonhwang, Cuiguan, Yulü and Eli No. 2.【Conclusion】It is evident that both the affiliation function method and the VIKOR method are forms of comprehensive evaluation of multiple indicators through weight changes. These methods have been widely utilised in other areas. The comprehensive evaluation rankings obtained by the affiliation function method and the VIKOR method are essentially equivalen, indicating that both methods can be employed for comprehensive evaluation of tree shapes and determining the suitability of different varieties. In the middle and lower reaches of the Yangtze River, the double-arm parallel trellis enables laborsaving and simplified cultivation of pear varieties of Housui, Wonhwang, Cuiguan, Yulü and Eli No. 2. Variety adaptability evaluation is a long-term process that requires commitment and dedication. Further research and verification are needed to determine the suitability of other tested varieties.