Why don't the grapes bloom?
During the fruiting period of grapes, many growers are often confused by the abnormal phenomenon of plants full of flowers but no harvest. As a perennial vine fruit tree, grape flowering and failure to bear fruit not only affects economic benefits, but also reflects key issues in cultivation and management. This article will systematically analyze the three general causes and provide practical solutions. 1. Core incentives for grape failure to bear fruit 1.1 Variety genetic characteristics Female flower varieties such as Heijixin and Anjiwen have a self-pollination rate of less than 5%, and must be paired with bisexual flower varieties such as Jufeng and Xiahei as pollination trees. It is recommended to allocate pollinated trees at a ratio of 1:8 when building a new garden to ensure effective dissemination of pollen. 1.2 Mismanagement of pruning and excessive closure of the crown structure can lead to: ① When the light intensity is less than 3000 lux, the flower bud differentiation is blocked. ② The proportion of long branches exceeds 30% and consumes too much nutrients. ③ As a result, the thickness of the mother branch is less than 0.8 cm, it is difficult to form effective flower ears. 1.3 Climate stress affects high temperatures above 35 ℃ during flowering period, which will burn stigmas, and air humidity> 85%, which will lead to pollen adhesion and failure. Continuous rainy weather will wash away more than 80% of the pollen, so special attention should be paid to the critical period of young fruit development 7 - 15 days after flowering. 2. Improvement plan for grape fruit hanging 2.1 Scientific plastic pruning adopts the "single arm" plastic shaping method:·Retain 8 - 12 buds in winter and prune mid-shoots·Remove double buds and weak buds in time during the growth period·Pick the fruiting branches 7 days before flowering and retain 6 - 8 functional leaves 2.2 Precise nutritional control Topdressing application of high nitrogen fertilizer (N-P-K = 20 - 10 - 10) during the germination period to promote the growth of new shoots. Use a high-phosphorus formula (10 - 30 - 10) during the bud appearing period, combined with 0.3% borax foliar spraying, significantly improve the fruit setting rate. 2.3 Artificial assisted pollination is carried out during the full flowering period (9 - 11 a.m.): ① Collect pollen from bisexual flowers with rabbit hair brush ② Gently sweep the inflorescences of female flowers in a zigzag route ③ Repeat the operation 2 - 3 times at an interval of 48 hours can increase the fruit setting rate to 75%. Through a three-pronged approach of variety improvement, tree body regulation, and environmental optimization, combined with careful management such as controlling prosperity before flowering, preserving moisture during flowering, and thinning fruit after flowering, the problem of grape flowers that are not real can be effectively solved. Growers are advised to establish a phenological period management log and continuously optimize cultivation plans.