Effect Of Pollination By Bombus Patagiatus And Apis Mellifera On Fertilization And Fruit Development Of Greenhouse Peach

Insect pollinators play an important role in increasing yield and improving fruit quality for many crops. With the development of peach cultivation within greenhouses, bee pollination has become an essential part of management. In order to study the pollination mechanism of greenhouse peach and to evaluate the pollination efficiency of Bombus patagiatus and Apis mellifera, flowering biology, fertilization and fruit development of greenhouse peach were examined in this study. The principal results include:(1)Flowering biology of different peach cultivars under greenhouse conditions. Four major peach cultivars (Prunus persica’Okubo’, P. persica ’Zaolupan’, P. persica ’Ruiguang5’ and P. persica ’90342’) were investigated in this study. The results showed that the ’full-bloom stage’ for single flowers of cultivar ’90342’lasted two days, significantly shorter than that of the other three cultivars, in which the full-bloom stage lasted4-5days. Significant variations were observed in pollen quantity. Cultivar ’90342’ had the largest number of pollen grains per flower (100360±8017), followed by ’Okubo’(91485±8002),’Ruiguang5’(73245±5034) and then ’Zaolupan’(59609±5048). Pollen viability lasted for just three days in ’Ruiguang5’and’90342’, whereas it lasted for6-7days in ’Okubo’ and ’Zaolupan’. The stigma receptive period lasted for6-7days after the flowers opened fully in ’Okubo’,’Zaolupan’ and ’Ruiguang5’. In contrast, the receptive period lasted for just three days after the flowers opened fully in cultivar ’90342’.(2)The impact of pollination by B. patagiatus and A mellifera on fertilization of greenhouse peach. In order to evaluate the impact of pollination by B. patagiatus and A mellifera on fertilization of greenhouse peach, pollen deposition, pollen tube performance, and ovary development were investigated in the ’Okubo’. The results showed that B. patagiatus deposited more pollen grains on peach stigma than A. mellifera during both single visit and one-day visit. In flowers pollinated by B. patagiatus, pollen tubes arrived at ovary and penetrated into ovule within7days after pollination, and half of the investigated flowers were fertilized within9-11days after pollination; in comparison, pollen tubes in flowers pollinated by A. mellifera arrived at the ovary within7-9days after pollination, but they did not penetrate into ovule until2-4days later, and half of the flowers were fertilized within7-9days after pollination. There was no difference in ovary development between the bee pollinated flowers and the bagged flowers within the first5days after pollination, however, an apparently faster ovary growth observed in bee pollinated flowers about5-7days later, with ovary from flowers visited by B. patagiatus grew faster than those visited by A. mellifera.(3)The impact of pollination by B. patagiatus and A. mellifera on fruit development of greenhouse peach. Without pollination, a significant fruit drop appeared in the’Okubo’4weeks after full blooming. In comparison, pollination by the two bee species significantly enhanced the initial fruit set. Furthermore, flowers pollinated by B. patagiatus produced significantly higher fruit set than those pollinated by A. mellifera. We also found that the fruit pollinated by B. patagiatus grew faster and harvested earlier than the fruit pollinated by A. mellifera. No significant differences were found in quality between fruit pollinated by the two bee species, however, bees pollination did improve the fruit VC, sugar and soluble solid content compared with fruit pollinated by hand.The results show that for greenhouse peaches, the bumblebee B. patagiatus deposits more pollen grains on the stigma, causes faster pollen-tube growth and ovary development, and results in higher fruit set and earlier harvest. We assume that higher pollen deposition can stimulate the process of fertilization and have a significant impact on fruit set. This study contributes new information on the pollination mechanism and will be useful for managing the bee pollination of greenhouse peach.