Key Management Techniques for Greenhouse Grapes During the Flowering and Fruiting Stage
Flowering and fruiting stage management is one of the important steps in early-forcing cultivation of greenhouse grapes. The quality of management directly affects the yield and fruit quality of greenhouse grapes. The following two aspects should be managed well:
????Regulation of Fruit Set Rate
????Pinching For vigorous fruiting shoots, twist the shoot above the inflorescence 7-10 days before flowering, and pinch while leaving 5-6 large leaves. This can significantly increase the fruit set rate (such as Kyoho, etc.). Watering during the flowering period and pinching after fruit set can significantly reduce the fruit set rate (such as Red Globe, etc.).
????Spraying Amino acid boron and amino acid zinc and other foliar fertilizers: 10 days before flowering, spray the leaves and inflorescences with chelated amino acid boron and chelated amino acid zinc foliar fertilizers specially designed for protected grapes, once every 7 days, for 2 consecutive sprays.
????Cluster Thinning Generally, cluster thinning is done when 4-6 leaves have unfolded. The principle of cluster thinning is: if cluster weight exceeds 500 g, moderate shoots have 1 cluster per new shoot, vigorous shoots have 2 clusters per new shoot or 3 clusters per 2 new shoots, weak shoots bear no flower clusters, and each new shoot has about 15-20 leaves; if cluster weight is less than 500 g, moderate shoots have 2 clusters per shoot or 3 clusters per 2 shoots, and vigorous shoots have 2-3 clusters per new shoot. Under normal circumstances, moderate shoots keep the first flower cluster, and vigorous shoots keep the first and second flower clusters or only the second flower cluster.
Cluster Trimming In order to obtain grapes with neat and attractive cluster shape and uniform berry size, cluster trimming should be carried out promptly after cluster thinning is completed.
① Cluster shaping for seeded varieties bearing fruit. Generally, cluster trimming is done about 7 days before flowering. Remove the branched clusters, shoulders and tips of the cluster in time, leaving only 9-10 cm in the middle of the cluster.
② Cluster shaping for seedless treatment of seeded varieties. For seedless treatment of large-berry varieties such as the Kyoho series, first remove branched clusters and overly large spikelets on the shoulders of the cluster as early as possible 1 week before flowering; secondly, from 3 days before flowering to the day of flowering, keep the top 3-3.5 cm of the flower cluster and remove all other spikelets. On the middle-upper part of the flower cluster, 2 small spikelets can be kept as identification markers. When carrying out seedless treatment and enlargement treatment, remove one spikelet each time to avoid omission or repeated treatment.
For seedless treatment of small-berry varieties, cluster shaping is carried out 2-3 weeks before flowering. First cut off a small portion of the small flowers at the tip of the cluster, then from the tip toward the base select and keep 12-14 small spikelets, keep two small spikelets on the upper part as markers for seedless treatment and berry enlargement treatment, and remove all other spikelets.
③ Cluster shaping for seedless varieties. For seedless varieties such as Summer Black, remove branched clusters and 2-3 spikelets at the base of the flower cluster as early as possible 1 week before flowering. The tips of overly large spikelets at the base should be cut off, and overly dense spikelets should be partially removed; lightly pinch the cluster tip or do not pinch the cluster tip, and select and keep 12-14 small spikelets from the tip toward the base.
Regulation of Fruit Quality
Berry Thinning Berry thinning standard: berries can rotate freely, and single cluster weight is 400-600 g (except Red Globe).
?? Deformed berries, small berries, diseased and insect-damaged berries, and relatively crowded berries in the cluster are generally thinned 1-2 times from 2-4 weeks after flowering. The first time is when the berries are the size of mung beans, and the second time is when they are the size of peanut kernels. Berry thinning standards should be determined according to different varieties. For varieties with a natural average berry weight below 6 g, it is suitable to keep 60-80 berries per cluster; for varieties with a natural average berry weight of 6-7 g, keep 50-70 berries per cluster; for varieties with a natural average berry weight of 8-10 g, keep 40-60 berries per cluster; for varieties with a natural average berry weight greater than 11 g, keep 35-40 berries per cluster; Red Globe is special and requires 80-100 berries per cluster.
When trimming the fruit cluster and thinning berries, because some varieties such as Red Globe are affected in berry growth when the cluster rachis and branch peduncles are injured, do not cut too close to the main axis of the cluster when removing cluster branches, and do not cut too close to the branch axis of the cluster when thinning berries. Be careful to retain a short "stub."
Bagging Bagging can significantly improve the appearance quality of the fruit. Bagging can be done after berry thinning is completed. The choice of paper bag depends on the variety. Generally, white paper bags are used for colored varieties, and yellow paper bags are used for green and yellow varieties. For varieties prone to sunburn, umbrella cultivation is best adopted to reduce sunburn.
Leaf Removal and Shoot Thinning Leaf removal and shoot thinning can significantly improve ventilation and light conditions on the trellis surface, which is beneficial for berry coloring, but leaf removal should not be done too early. It is best done 10 days before harvest. If the technique of using lateral shoot leaves is adopted, the time for removing old leaves can be moved earlier to when the fruit begins to ripen.
When thinning shoots, generally 3000-5000 new shoots per mu should be retained. This ensures both an adequate number of retained new shoots and ventilation and light penetration. Shoot thinning is generally carried out when new shoots have unfolded 5-7 leaves.
Girdling or Ring-Barking Before berry coloring, girdling or ring-barking at the base of the fruiting mother branch or the base of the fruiting branch can promote berry coloring, advance ripening by 3-5 days, and significantly improve fruit quality.
????Hanging and Laying Reflective Film After ground temperature reaches a suitable level, hanging and laying reflective film can significantly improve fruit quality and promote fruit ripening.
Make Full Use of Lateral Shoot Leaves Pay attention to strengthening the use of lateral shoot leaves, because in the later stage of grape growth and development, photosynthesis mainly relies on lateral shoot leaves, and this is even more obvious in protected grape cultivation.
Shoot Twisting During the young fruit development stage, this can significantly inhibit excessive growth of new shoots, promote fruit ripening, improve fruit quality, and promote flower bud differentiation.
????Spraying Amino Acid Series Foliar Fertilizers From the young fruit development stage to the fruit ripening stage, spray amino acid calcium foliar fertilizer once every 10 days; during the berry coloring stage, spray amino acid potassium foliar fertilizer once every 10 days.
Reasonable Load In accordance with the requirement of balancing quality and yield, the yield per mu is generally controlled at around 2000 kg.