Evaluation on High-yield Cross Combination of Ricinus communis L. Suitable for Mechanical Harvest

Objective A joint evaluation on Ricinus communis cross combinations was conducted to provide a theoretical reference for screening high-yield varieties suitable for mechanical harvest.

Method The yield trait, adaptability for mechanical harvest and photosynthetic performance of 30 R. communis cross combinations were jointly evaluated by grey relational analysis, principal component analysis and cluster analysis.

Result In the grey relational analysis, 6 combinations including N₁₉ (0.768), N₇ (0.751), N₁₁ (0.727), N₁₀ (0.717), N₆ (0.713) and N₁₃ (0.712) with weighted correlation degree between various combinations and the ideal varieties were screened out. Among which, the former 4 combinaitons had higher weighted correlation degrees than that in Zibi 5 (0.714), and the weighted correlation degrees of the latter 2 were close to that in Zibi 5. Principal analysis results showed that, 10 traits were classified into 3 principal components, namely, plant type factor, yield determining factor and photosynthetic and branching angle factor, with a cumulative contribution rate of 67.07%. Among the 30 combinations, the comprehensive scores of 21 combinations were higher than that of Zibi 5 (-0.699), and only 4 combinations, N₁₈ (2.370), N₄ (1.848), N₁₉ (1.742) and N₁₁ (1.019) had comprehensive scores larger than 1, of which N₁₉ was the most prominent with a much higher score than that in other 3 combinations. Cluster analysis revealed that, the 30 combinations could be classified into 4 groups at Euclidean distance value equal to 22. Among them, Group IV members (including N₁₉, N₁₁ and N₃₀) with the best overall performance was most similar to the ideal varieties based on the average performance in each cluster, however, the branching angle (59.10°) was large and still expected to be improved.

Conclusion Based on the above 3 evaluation results, the comprehensive evaluation avoids the acceptance of redundant germplasm and the loss of elite germplasm. The N₁₉ and N₁₁ with high yield, good plant type and high photosynthetic rate were selected as the optimal Ricinus communis cross combinations, and their comprehensive performances were better than that of Zibi 5, providing a direction for further improvement of varieties.out of varieties.