Effects of top pruning on seed setting of aged mother trees in orchard of Pinus sylvestris var. mongolica

ObjectiveMongolian pine (Pinus sylvestris var. mongolica) is one of the important tree species for soil and water conservation and windbreak and sand fixing in arid and semi-arid sandy areas of northern China. Effects of top pruning on seed setting of aged mother trees in orchard of P. sylvestris var. mongolica were studied, which provided basic information for high quality, high yield and scientific management of Mongolian pine seed orchard.

Method18 clones of P. sylvestris var. mongolica 24-year-old mother trees in Yulin P. sylvestris var. mongolica seed orchard of Shaanxi Province, northwestern China were selected as the research object, and the differences of 8 indexes of cone yield, cone size, seed yield and quality were compared between top pruning and non-top pruning.

ResultThe results showed that top pruning treatment had no significant effect on single cone mass and cone mass per tree, but the average gain value reached 24.84% and 23.82%, respectively. This suggested that top pruning treatment could improve the yield of the cones of Mongolian pine mother trees in a certain extent. Top pruning treatment had significant effect on seed mass per tree and seed-production ratio, and the average gain values of seed mass per tree and seed-production ratio were 81.38% and 55.94%, respectively. It indicated that top pruning treatment increased the seed yield of Mongolian pine mother trees. The average values of cone short diameter and cone short diameter of mother trees after top pruning were 7.43% and 24.96%, respectively, and top pruning treatment had little effect on cone size of Mongolian pine mother trees. The average values of thousand seed mass and seed goodness of mother trees after top pruning were 7.43% and 24.96%, respectively, and most clones had positive gain in thousand seed mass and all clones had positive gain in seed goodness. Top pruning had no significant effect on thousand seed mass but had significant effect on seed quality. It indicated that top pruning treatment could improve seed quality of Mongolian pine mother tree.

ConclusionThis study improves that top pruning could increase the yield and improve quality of P. sylvestris var. mongolica aged mother trees in sandy area.