Grape flowering to young fruit expansion is a very important stage in grape growth period. Whether the management of this stage is in place directly affects the yield and quality of grapes in that year. The main points of this period management are as follows:
During the grape production cycle, from the beginning of flowering to the end of flowering, the normal year lasts about 4-14 days, mostly 7-12 days.
Temperature, humidity, drought and wind are the main factors affecting the flowering and Fruiting of grapes. Flowering period requires higher temperature. When the temperature reaches 25 C or above, grapes blossom in large quantities, and the optimum temperature is 27.5 C. When the temperature was lower than 15 C, grapes could not blossom normally and fertilization would be inhibited.
The optimum relative humidity at flowering stage is 56%. If it is rainy and drought, it will affect flowering and pollination. Soil moisture is higher, flowering time is earlier, on the contrary, flowering late. Wind is also an important factor affecting flowering, strong wind is not conducive to flowering, will aggravate the fall of flowers.
During the grape flowering period, 6-11 a.m. is the peak flowering period, and 7-9 a.m. is the peak. 3-5 days after anthesis is the first physiological fruit drop stage. During the grape flowering period, a lot of nutrients are consumed due to flowering, flower bud differentiation, branch and leaf growth. During this period, nutrient contention between vegetative growth and reproductive growth is very fierce. If a large number of nutrients are consumed on shoot growth and reproductive growth nutrients are not satisfied, it will cause a large number of buds before flowering, and will continue to fall after flowering, thus reducing fruit setting rate. If there is too much water in the soil and the root system is not ventilated well during the flowering period, the nutrient absorption will be affected and the flowers will fall. In view of the conditions and physiological characteristics of grape flowering, the production and management of grape flowering period should focus on the following aspects:
1. Topdressing
In order to alleviate the competition of nutrition for vegetative growth and reproductive growth at flowering stage and meet the needs of flowering and fruit setting, top dressing must be carried out before and after flowering, and 0.2% - 0.3% boric acid or borax solution should be sprayed before flowering to promote pollen tube elongation and increase fruit setting rate. At the same time, we should do a good job in the management of branches and vines and improve the ventilation and light transmission conditions in the garden. In order to save nutrient consumption during grape flowering period, it is necessary to bind vines, remove auxiliary shoots, pick hearts, pinch spikes and remove auxiliary spikes in time.
2. Strengthen Temperature and Humidity Control
Grapes cultivated in greenhouse must pay attention to the control of temperature and humidity in greenhouse. In order to improve the germination rate of pollen and ensure the smooth progress of pollination and fertilization. Temperature management index in greenhouse: during the day, it should be kept at about 28 degrees C, and at night it should be kept at 16-18 degrees C. Humidity control: When it comes to flowering period, irrigation should be stopped. The air humidity in the shed should be controlled at about 50%, and regular ventilation and ventilation should be paid attention to. It is difficult to control the temperature of grapes cultivated in the open field, but the soil moisture should be loosened and dehumidified to make the humidity in the garden beneficial to flowering and fruit setting.
3. Pay attention to the sorting and arrangement of spikes
This is an important measure to control yield reasonably and keep ears uniform and tidy. We must do a good job of it.
4. Artificial assisted pollination of female flower varieties
Most grape varieties are hermaphroditic flowers, which can be naturally fertilized. However, because of male core degeneration, female flower varieties need to be pollinated to obtain higher yield. Therefore, it is necessary to attach importance to artificial assisted pollination.
5. Plant growth regulators should be used in good time for varieties requiring denuclearization treatment
For example, Giant Peak cultivars were treated with GA3 for the first time at full flowering stage, and spikes were treated for the second time 10-15 days later.
6. Pest and Disease Control
Preventive drugs must be used 2-4 days before grape blossoms. Focus on prevention and control of gray mold, blackpox, anthrax, downy mildew, rachis brown blight, winged moth, scarab.