GUAVA TECHNICAL print the page Introduction Guava (Psidium guajava L.) is an important fruit crop of India and has gained considerable importance because of its high nutritive value, availability at moderate price, a pleasant aroma and good flavour. Guava is one of the most common fruit liked alike by both the rich and the poor. Guava is a rich source of vitamin C and pectin. It contains 82.5% water, 2.45% acid, 4.45% reducing sugars, 5.23% non-reducing sugars, 9.73 brix, 0.48% ash and 260 mg vitamin C/100 g fruit which differ with the cultivar, stage of maturity and season. The fruit is relished when mature or ripe and freshly plucked from the tree. It is also used for many preparations like jelly, cheese and juice.   Propagation Although cross-pollination is common, guava is basically a self-pollinated crop. This result in large variability in the seedling population from which promising genotypes have been selected in different agroclimatic regions of the country. Guava is also propagated through seed. Inarching, layering and air-layering are commonly practiced. Propagation through root suckers, root cuttings and budding is sometimes successful. Propagation is generally done during the rainy season. The new plants are ready to be set out after a year. The usual distance for planting is 5.5 to 6 metres. Propagation by seeds during early days gave rise to considerable variability which was utilized both by growers and horticulturists for selection of better types, and thus a large number of varieties came into existence and some of these types were later propagated vegetatively for commercial cultivation.   Varieties More than 150 genotypes including Psidium spp are available in the Indian collections and are being maintained at several centres in the country in field gene banks. Some of the common varieties grown in India include ‘Allahabad Safeda,’ the most popular variety. ‘Chittidar,’ ‘Sardar,’ ‘Seedless’ and ‘Red Fleshed.’   Varietal improvement According to the Department of Agricultural Research and Education, ICAR, Government of India, in 1999-2000, guava variety ‘Lalit’ has been released by the CISH, Lucknow, for commercial cultivation. Its fruits are medium sized (185 g) with attractive saffron-yellow colour and red blush. Its flesh is firm and pink with good blend of sugar and acid. It gives 24% higher yield than popular variety ‘Allahabad Safeda’. This is suitable for both table and processing purposes. Two hybrids, H 21 and H 136, have also been isolated for red pulp and soft seeds, and high TSS (12.5° Brix).   Flowering Three flowering seasons for guava have been observed in the peninsular regions of India, i.e. amba bahar, mrig bahar and hastha bahar. In north Indian sub-tropics there are only 2 flowering seasons, i.e. April-May for rainy-season crop and August-September for winter-season crop. The peak anthesis is found between 5 and 6:30 AM in most of the varieties under south Indian conditions. However, under north Indian conditions it has been between 6 and 7:30 AM. The dehiscence of anthesis starts 15-30 min after anthesis in all the varieties and continues up to 2 hr under Bangalore and Coimbatore conditions. Pollen fertility was found high in all the cultivars of guava at Coimbatore. For artificial germination of pollen 4% sucrose solution was found the best medium in different cultivars. The pollen-grains of guava vary in size from 18.9 to 21.8 µ and are round and large. The stigma becomes receptive 2 days before dehiscence and remains so up to 4 days afterwards.   Hybrid Research In India breeding work for guava improvement has been done at several research institutions. At HETC, Basti, and a number of cross-combinations, viz. Seedless x Allahabad Safeda, Seedless x L 49, Allahabad Safeda x Patillo, Apple Colour x Red Fleshed and Apple Colour x Kot Prud were made. None of the 55 hybrids obtained from these crosses were found promising. At Fruit Research Station, Sangareddy, Andhra Pradesh, 2 hybrids, Safed Jam and Kohir Safeda, were selected from the crosses of Allahabad Safeda x Khoir and Khoir x Allahabad Safeda respectively and released. These hybrids have been recommended for semi-arid tropical areas and have also been found suitable for juice purpose.   Nutrient Management Guava generally suffers from zinc deficiency in India, but sometimes in certain areas it suffers from boron deficiency also. In north India pre-flowering spray of 0.4% boric acid and 0.3% zinc sulphate corrected the deficiency. It also increased the fruit size as well as yield. Studies conducted at Gandhi Krishi Vigyan Kendra (GKVK) and IIHR, Bangalore, indicated common micronutrient deficiency of Zn. Soil application of 800 g ZnSO4/tree or foliar spray of 0.5% ZnSO4 and 0.4% boric acid 10-14 days before every flowering, effectively eliminated deficiencies in guava. At the University of Agricultural Sciences (UAS), Bangalore, bronzing was a common malady and the healthy leaves had narrow P: Zn, N : P and K:Zn ratios than the bronzed leaves. Soils in badly affected orchards showed very low pH and were poor in P, K, Zn and organic carbon. The poor nutrient status of N, P and Zn was found to be the cause of bronzing. Soil applications of N, P, K, Zn at 200, 80, 150 and 50 g/plant/year respectively or foliar applications of these nutrients each at 2% for 4 months have resulted in reduction of bronzing.   Disease Management Guava wilt, anthracnose, dieback, canker, fruit rot and dry rot are some the common diseases that effect guava. Remedial measures for most of these diseases have been worked out but some diseases like guava wilt are still unresolved. Guava suffers very badly from the wilt disease which are there in two forms viz. dieback or slow wilting and quick wilt. The disease causes about 20-100% mortality with fruit yield reduction of 12-20 tonnes/ha. Research is still going on to find a remedy for this disease. Some experts’ point out that growing of new disease resistant varieties is probably the best way out. Anthracnose is a another serious problem in but it can be effectively controlled by spraying Difolation 0.3%, followed by Dithane Z-78 at 0.2% at 1-month interval. Fruit canker is caused by Pestalotia psidii generally occurs on green fruits and can be controlled by 3 or 4 sprayings of 1% Bordeaux mixture.   Pest Management Out of the 80 insect spp. that guava is attacked by, only a few cause economic damage. Major pests identified in India are fruit-flies, bark-eating caterpillar, lepidopterous fruit-borers, scale insects and mealy bugs. The pests and their recommended remedies are mentioned below: Name of Pest Recommended Remedy Fruit-flies (Dacus dorsalis, D. diversus and D. zonatus) use of protein hydrolysate poison baiting and spraying with 0.03% Phosphamidon or Oxydemeton methyl   Post-Harvast Management Harvesting, handling and storage After 100-110 days of growth, guava fruits attain maximum growth, sucrose content and pectin. As the fruit is highly perishable, it needs to be marketed immediately after harvest. However, sometimes it is stored for a few days to meet the market demand. Ripening could be retarded, if mature green guava fruits are treated with MH and gibberellic acid or hastened by 2, 4-D, 2, 4, 5-T and ethephon. Fruits of Safeda guava could be stored for 4 weeks in cold storage at 10°C. Irradiated fruits showed slower rate of ripening, sugar accumulation and weight loss during storage. Fruit packaging The shelf-life of fruits can be extended by waxing, pre-packaging and fungicide treatments. The fruits are either packed in boxes or in baskets of different sizes. Fruit processing It is one of the important tropical fruits known for its intensive flavour, high vitamin content and substantial amounts of B vitamins, calcium, iron and phosphorus. Only a small quantity of the production is utilized for processing in the form of jelly, canned cups, juice and nectar. Cheese, toffee, bar powder, flakes and strained baby foods have also prepared besides commercial pectin.