Pomegranates bloom all year long in a tropical climate. There are three separate flowering seasons in subtropical central and western India, however, yield and quality are not as good in all crop harvests. It is critical to identify crop flowering and fruiting habits, as well as which bahar will produce a productive crop when all elements associated with that bahar are taken into account.
Objectives of crop regulation
The main objective of crop regulation is to force the tree to rest and produce prolific blossoms and fruits during any one of the two or three flushes. Besides, some objectives are as under:
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To obtain the suitable crop at a desired season
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To regulate a uniform and good quality of the fruits
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To maximize the production as well as profit to grower.
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To reduce cost of cultivation because uninterrupted continuous blossom would produce light crops over the whole year and require a high cost for the monitoring and marketing.
Ambebahar (spring season flowering), mrigbahar (June-July flowering), and hastabahar (August-September flowering) are the three main flowering and fruiting seasons of the pomegranate (October- November flowering). Plants may continue to bear blooms and small crops irregularly at different times of the year under such conditions, which may not be commercially viable. Only one harvest each year is desirable for commercial production. Bahar selection is influenced by location as well as certain current production constraints such as irrigation water availability, fruit quality, market prices, and disease and pest infestations. Water supply is a major challenge for pomegranate growers in arid and semi-arid regions throughout the summer season. They constantly avoid picking ambebahar crops and limit harvesting to the winter months. Some farmers prefer Hastabahar because it has less water.
Principles of flower regulation
Crop regulation's main premise is to alter the pomegranate plant's natural flowering in a desired season to maximize fruit yield, quality, and profitability. It is beneficial for the most efficient and long-term use of resources, as well as high production of high-quality fruits. Environmental and genetic factors influence the onset of flowering and the regulation of flowering. Pomegranates bloom intermittently in the arid and semi-arid regions from February to October. To avoid this, pomegranate crop regulation is done by a set of mechanisms at certain periods. All commercially grown types in the country are extremely susceptible to diseases and pests, particularly Bacterial Leaf Blight, Scorching, Nematode, Termite, and Mite, among others. Therefore, availability of irrigation water, climate, pest and disease infestation, and market demand are the major issues for flower regulation in pomegranates. Indian varieties mostly produce flowers throughout the year.
Methods of crop regulation in pomegranate
Many factors influence flowering, including irrigation withholding (lack of moisture), defoliants, plant growth hormones, nutrient status, and canopy management (training and pruning), among others. Irrigation is stopped one to two months before the required bahar in the pomegranate is obtained. After that, minor pruning and then foliar spraying of ethrels defoliant are used to get rid of the leaves. The topsoil around the tree was dug up to a depth of 30 cm, equal to the leaf canopy. Manure and fertilisers are spread on the soil, which is subsequently levelled. Following the administration of the necessary dose of manure and fertilisers, light watering is performed. The better flowering, good floral sex ratio, higher fruit setting and ultimately higher quality yield of fruits may be taken in year at a desired season by these treatments. There must be good growth and development of pomegranate plants up to first two years. Bahar treatment must be started from third year onwards for taking better quality fruit production. Bahar treatment is done in the following ways in pomegranate.
Flowering due to the stress of water scarcity
The main principle of withholding of irrigation is to provide rest to the plant. It results in an increase in the number of flowers and the accumulation of large amounts of food to increase growth in the coming season. In light sandy soils, irrigation is withheld for one month, while in loamy soils, it is withheld for one and a half months. When pomegranate plants have the desired leaf fall, it is the optimal condition for crop regulation (50 to 70 % ). Plants generate osmatin, proline, and arginine protein in response to water stress. Proteogenic amino acids, such as prolines, accumulate as a beneficial solute in plants under stress and non-stress conditions, providing a high capacity for stress tolerance. These amino acids also aid in the stimulation of flowering in plants under water stress conditions. As a result, plants generate more flowers, have a better sex ratio, and produce more fruits.
Use of chemicals for flowering
In recent times, the foliar spray of ethrel (1-2 ml per litre) is extensively practiced for crop regulation in pomegranate crop. Ehtrel hormone stimulates the enzymes i.e. cellulase and polygalacteronase for cell smelting. This condition is considered good for achieving more flowering, good sex ratio and high yield.
Flower regulation by cultural practices
Higher flowering % and quality fruit production in pomegranates are best achieved through canopy management strategies such as training, trimming, and fertiliser control (carbon nitrogen ratio). Pomegranate trees can be trained to be multi-stemmed or single-stemmed. To avoid stem borer damage, 3 to 4 stems are usually kept, while the remaining shoots are cut, giving the tree a bushy appearance. Pomegranate plants are often trained using an open centre technique in their early years. After withholding watering for 15 to 20 days before starting a new bahar, light pruning is done. To prevent fungal infestation, 10% Bordeaux paste is applied to trimmed plant portions.
Mrigbahar is regulated in dry areas to ensure high-quality crop production. For regulating of crop in dry areas, withholding of irrigation is done in April- May. Subsequently light pruning and spraying the mixer of 1000-2000 ppm ethrel and 0.5 per cent diammonium phosphate is followed. Flowering takes place in June - July. This gives good quality fruits in November- December. For getting good quality yield 60 to 80 fruits should be retained on single plant.
Insect-pests and diseases management
Crop regulation is an effective method of controlling insect pests and diseases. Depending on the dose of defoliant used for crop management, leaf falls range from 50 to 100 percent. Insect pests and diseases should be eradicated to some part by collecting and burning fallen leaves. As a result, it aids in the prevention of insect pests and diseases, as well as the reduction of insecticide use.
Author
Lokesh Kumar, Dr. R.L. Bhardwaj
Department of Horticulture, Agriculture University, Jodhpur