Augment yield and quality of guava (Psidium guajava L.) - In Indian conditions
Guava (Psidium guajava L.) popularly known as 'Apple of the Tropics' belongs to the family Myrtaceae with its unique flavor, taste, and health-promoting qualities is one of the commercial fruits of tropical as well as subtropical regions. The fruit is botanically berry and the trees of guava are very hardy, fruits have high nutritive food value being an excellent source of vitamin C, high quality pectin and rich source of calcium. It is also called as "poor man's apple" because the fruits are sold at a cheaper rate during the season and hence, they are within the reach of the common people. Guava is a native of tropical America and seems to have been growing from Mexico to Peru. Important guava growing countries in the world are Cuba, Brazil, Mexico, Southern China, India and Malaysia. Guavas actually thrive in both humid and dry climates and can tolerate brief periods of cold spells, but can survive only a few degrees of frost. Adaptability makes it a favorite commercial crop in some tropical areas.
Regulation of crop in guava is very important because of poor quality of fruits, which are generally harvested during monsoon season. Winter crop is of superior in quality in general as compared to monsoon season crop, new growth starts in guava trees during spring, monsoon, and winter season. It results either on emergence of new shoots or growth in previous season shoots. During spring, maximum growth takes place. There is emergence of new shoots from the axil of the one-year-old shoots. New growth/ current season's growth gives fruiting. Due to poor quality and glut in the market, monsoon season crop fetches relatively poor returns. There is a need to regulate crop in such a way as to achieve fruit production in winter season only.
In guava, two distinct seasons of flowering, spring (March-April) and monsoon (June-July), occur from which fruits ripen respectively during monsoon season and winter. Sometimes a third flowering, although sparse, also occurs during winter (October-November) giving fruits in spring through summer. In south India, guava flowers twice in September-October and February-March, whereas in Western India, October-November flowering is also common. Which results in no rest period and ultimately guava tree bears small crops at different times of the year, this pattern of flowering and fruiting is not desirable for commercial cultivation. Root pruning of guava to regulate the season of harvesting by withholding of water is known as bahar treatment. The well defined periods are:
Ambe-bahar: When guava tree flowers during February to March or spring season, this flowering period is known as ambe bahar. The fruits are ripened from July to September or in monsoon season. The fruits obtained during this season are insipid, watery and poor in quality.
Mrig-bahar: When guava tree flowers during June -July or monsoon season, this flowering period is known as mrig bahar. The fruits are ripened from November to January or in winter season. The fruits obtained during this season are excellent in quality and, therefore, the guava trees are made to produce the mrig bahar flowering only.
Hasth-bahar: Sometimes, guava tree produces flowers in October, this is, known as hasth bahar. The fruits are ripened from February to April. The quality is good, but yield is very low. However, it fetches good prices. Hasth bahar in guava is not mostly chance crop. Hasth bahar is observed in Western and Southern India.
Throughout India Mrig bahar (winter) is preferred over Ambe bahar (monsoon) and Hasth bahar (spring). Therefore it is Advisable to take only one crop every year. This requires regulation of flowering, to obtain the most profitable crop by methods like,
Methods of crop regulation
• Withholding irrigation
• Root exposure and pruning
• Shoot Pruning
• Flower and fruit thinning
Withholding of irrigation: Withhold irrigation from February-May to guava trees. So that, tree sheds its Tree sheds its leaves during hot season (April-May) and Goes to rest. During rest period, tree can conserve food material in its branches. In the month of June tree is well cultivated and manured followed by Irrigation. After about 20-25 days tree produces profuse blossoms. Fruits mature during winter.
Root exposure: It is recommended to suppress the monsoon season crop so as to get a good winter crop. Before two months to flowering, Irrigation is withheld; soil around the basin of the plant is removed carefully (about 45-60 cm radius). So that, main roots are exposed to sun, fibrous roots are removed. As a result, upward translocation of water and downward translocation of food materials are impaired. So the tree sheds leaves during rest period. After 3-4 weeks, the exposed roots are again covered with the soil. Manuring and watering may be followed. Within 3-4 weeks, the tree would blaze into blossoms.
Root Pruning: Every year the trench is dug a few inches further away from the trench of the previous year and the roots pruned to within one and a quarter to two inches of the stumps of the former year. After pruning trench is filled with manures liberally, the tree is thus fed and watered artificially in a restricted area. As a result of this, the Circular mass of fibrous roots increases very slowly from year to year and the tree makes short but stocky and ripened shoots. Root pruning is not, however, recommended as a regular orchard practice and has to be used sparingly as it affects economic life span of the tree and also affects growth of the tree.
Shoot Pruning: It is practiced to affect the monsoon season crop, when judiciously regulated by checking the April-May flowering. Hence by using this technique vegetative shoots may remain blind and later on flower buds appear for winter season crop, resulting in to longer age of bearing shoot with good fruit quality.
Flower and fruit thinning
• Manual thinning
• Chemical thinning
Manual thinning: Hand thinning of flowers and fruits was recommended to reduce the monsoon season crop and to get more fruits in winter. This can be done manually on a small scale. Fruit thinning helps to increase the individual size, weight and quality of fruits.
Chemical thinning: Growth regulators and certain chemicals are very effective in thinning of flowers, which reduces the monsoon season crop and increasing the winter season crop.
Bending: Bending is a technique with its scientific base, has a great potential in enhancing the productivity of guava through regulating the crop and producing more number of lateral shoots. Upright growing branches will not produce auxiliary growth leading to their terminal portions should be buried inside the soil and tied strongly to pegs driven in the soil around trees. By this Dormant buds are accelerated and induced to produce new flush, which will result in flowering and leading to high yields.
Effect of crop regulation
• Fruit set
• Fruit size
• Fruit weight
• Fruit number
• Fruit quality
The fruits harvested during monsoon season are small in size, inferior in quality and highly susceptible to pest and diseases, thus, resulting in poor income to growers. Hence, better quality and higher price could be obtained from the winter crop by following crop regulation to avoid monsoon season crop.
About Author / Additional Info:
I am working as a scientist at NBPGR, New Delhi