PRECISION TECHNOLOGIES FOR IMPROVED PRODUCTION

Selection of Varieties

Although, a large number of varieties are known in guava, Allahabad Safeda and Sardar (L 49) form the main stay of Indian guava industry, owing to its high yield, wide market acceptability and high economic return. These cultivars have assumed the status of commercial cultivation.

Allahabad Safeda : Medium to tall, upright growth in nature, heavy bearer, foliage

mostly dense, tendency to produce long shoots. Crown broad and compact, often dome-shaped, rarely loose. Fruit medium, roundish in shape, smooth skin, white flesh and with few soft seeds, keeping quality is good.

Sardar (L 49) : Vigorous, spreading and profuse bearing, heavy branching type, crown

flat, fruit large, roundish ovate in shape, skin colour primose-yellow, white flesh, seeds soft and in plenty.

Apart from above two varieties, some of the cultivars which are grown in some specific areas are Chittidar, Red Fleshed, Apple Colour, Anakapalle, Banarsi Surkha, Sangam and Dharwar.

New Promising Cultivars

Lalit, a new variety of guava has been released by the CISH, Lucknow, for commercial

colour with red blush. Its flesh is firm and pink with good blend of sugar and acid. This is suitable for both table and processing purposes. The pink colour in the beverage remains stable for more than a year in storage. The jelly made of this variety has better flavour and appearance. It gives 24% higher yield than popular variety Allahabad Safeda (4).

Pant Prabhat has been selected by the Department of Horticulture, GBPU&T,

Pantnagar (Uttranchal), for commercial cultivation (Fig. 2). Plant growth is upright with broad leaves, tree highly productive (100-125 kg), fruit round, peel smooth and light yellow in colour, fruit medium (150-172 g), pulp white, seeds small and soft as compared to Sardar. Sweet taste with pleasant flavour, ascorbic acid content varies from 125 mg (rainy season) to 300 mg/100 g fruit weight (winter season). TSS varies from 10.5 to 13.50o _Brix.

Multiplication of Genuine Planting Material

Genuine planting material is the basic requirement for quality guava production. Most of the nurseries in private and public sectors do not produce standard plant material which ultimately affect not only the production potential but also the yield of quality fruits. The guava industry is ravaged by wilt. To overcome this problem, production of disease-free quality planting material is very important. There is an urgent need to contain the spread of wilt through infected orchard.

Sapling must be healthy and vigorous at the time of planting. Plants propagated from diseased, old and exhausted mother tree, never develop into good nursery plants. Preferably, nursery stock should be raised from true-to-type, healthy and vigorous

Approaches and Strategies for Precision Farming in Guava

young mother tree planted in separate block and used exclusively for propagation programme. Such trees, when they lose vigour due to continuous use for a number of years, should be invigourated by pruning practices. Better results are achieved with vegetative propagation. As compared to seed propagation, vegetative propagation in guava results in a uniform crop and short juvenile phase. There are various methods of vegetative propagation but budding and stooling are found to be better.

Budding: Budding is done in several ways, but patch budding is considered to be

most efficient and satisfactory method of propagation in guava which gives high rate of success. However, success depends on vigour of both scion and stock. Seedlings of about one- year-old, uniform and active in growth are selected. The thickness should not be more than that of an ordinary lead pencil. This method is most satisfactory when vigorously growing plants, 1.25-2.5 cm in diameter, are used as stock. The trees from which buds are taken should be highly vegetative lush, succulent growth to permit easy separation of buds from the stem. It is better to take well-swollen and unsprouted dormant buds from leaf axil of mature twigs of the scion variety. A patch, approximately 1 cm (0.5 inch) x 1.5 cm (0.75 inch) seems to take better than when a smaller patch or bud is used. Similarly, 1-1.5 cm long patch is removed from the rootstock and bud is fitted into the remaining portion on the stock seedling. Bud should be fitted at a height of nearly 15cm above the ground level. Polythene strip is used for keeping the buds close to the stock. When the bark adheres tightly to the wood, budding is usually successful. After about 2-3 weeks of budding the polythene strip can be opened to examine the success. In successful cases, about one-third of top of shoot of the rootstock can be removed for forcing the growth of buds. The remaining two-thirds can be removed after three weeks of the first cutting, leaving about 2-3 cm above the bud. The best time for budding is May, July and August.

Stooling: Stooling is the easiest and cheapest method of guava propagation. This

method can be used for quick multiplication of desired varieties and also rootstocks. In this method, self-rooted plants (cuttings and layers) are planted 0.5 m apart in the stooling bed. These are allowed to grow for about three years. Then these are cut down at the ground level in March. New shoots emerge on the beheaded stumps. A 30-cm wide ring of bark is removed from the base of each shoot rubbing the cambium of the exposed portion in May. All the shoots are mounted with the soil to a height of 30 cm. The soil is covered with mulch to conserve the moisture. After a period of two months of the onset of monsoon, the shoots are detached from the mother plant at ringed portion and planted in the nursery. The shoots are headed back to maintain the root and shoot balance before planting in the nursery by following the technique of

ringing and mounding of the shoots, second time stooling is done on the same mother shoot in the first week of September. The rooted shoot layers are detached in the first week of November. Thus, stooling is done twice on the same mother stool in a year. The stooling of a mother stool can be done for many years. With the advancement of its age, the number of stool layers also increases every year. The growth and development of a stool layer are better than seedlings. The application of rooting hormone is not required.

Establishment of Guava Orchard

Guava is not difficult to grow, however, profitability depends on the ability of the careful management programme to maximize production and to reduce fruit losses. Commercial production from guava orchard begins on third year after planting and cropping may continue for 40 years or more. Therefore, performance of a orchard depends on its management, which includes water and nutrient management, selection of right cultivars, planting technique, canopy management for flowering and fruiting, improved light efficiency through pruning to optimise the quality and production of young and bearing trees.

Planting Technique

Before layout, the land should be well ploughed 3-4 times. The square or rectangular system of layout should be preferred as it facilitates orchard operations. The pits of 75 cm x 75 cm x 75 cm size should be dug before the monsoon at a distance of 5m x 5m which results in 400 trees/ha. Rows should be planted in north-south directions to allow maximum sunlight exposure. After 15-20 days, the pits may be filled with top soil mixed with 30-40 kg of well-decomposed cattle manure and 1.0 kg of superphosphate. The pit is irrigated after filling so that the soil mixtures settle down. Pit should be treated with Tricel (2.5 ml/litre of water) or dusting of Seiven (20 g/pit) to prevent white ant (termite) infestation. After making the exact position of the plant in the pit with the help of planting board, scoop out enough soil from the centre of the pit so as to accommodate the guava plant with its ball of earth. The plant is placed straight in the centre of the pit. The soil around the plant is pressed firmly and a small basin is made for regular watering. Immediately after planting, it should be copiously watered. It is desirable to stake the plant to avoid breakage especially at the graft joint and to keep it erect. Planting is done from July to October.

Training and Pruning

Approaches and Strategies for Precision Farming in Guava

number of shoots and higher yield. Pruning begins at an early stage of plant growth to develop single trunk trees with well-spaced scaffold branches to form the framework. Within the first 3-4 months after planting, the guava plant needs to be pruned and trained to allow maximum production of fruit as soon as possible and at the lowest possible cost (6). In the initial stage, trees are trained to a single upright stem with the fruit bearing lateral structural branches emerging from the single stem beginning at a height about 50-70 cm from the ground level, rather than having these laterals emerging at ground level, as usually in the case of untrained trees. As the trees become older and better able to support the scaffold branches, the main trunk can be extended upwards by cutting off the lower interfering scaffold branches.

Lateral structural branches should be pruned and trained to radiate outwards from the central axis of the tree. Any branch that does not fix into such pattern should be gradually removed. Essentially, then, guava trees are pruned to increase yield and to reduce the total cost of field operations by eliminating obstacles and branch hazards which slow down easier movement around the trees. Dried twigs should be removed regularly. Suckers emerging from the soil (ground level) should also be removed regularly as presence of suckers' results in poor growth of the plants. A properly pruned and trained tree can be gradually confined to a foliage canopy approaching 4m in radius. The angle between the branches of the stem must be wide so that sunlight is able to penetrate into the centre of the tree. Trees are pruned and fertilised to induce new axillary growth upon which flowers will be produced. Branches grown horizontally are far more productive than vertical ones(6). For dessert cultivars, an ideal tree shape is one with no branches 50-70 from the ground and 3-6 horizontal branches.

High-density Planting

Due to recent advancements in horticultural practices on one hand, and agricultural engineering on the other, establishment of densely planted, dwarf, and intensive orchards is becoming more and more a universal challenge for all guava growers (Fig. 3). Among the production practices, tree management, specifically size control, has become a priority for the modern guava producer due to the demands imposed by modern markets in terms of production costs, yield and fruit quality. Early management of apical growth is necessary to maintain height control in guava (6). Recent advances in fruit tree training techniques are rapidly changing production strategies throughout the tropics. Modifications in training techniques influences plant spacing and production decisions. Similarly, unpruned tall and crowded guava trees pose a number of problems while carrying out various cultural operations. Canopy design and shape influence light

interception (Figs. 4 A and B) and higher monetary returns can be assured to guava growers. In fact, guava responds well to canopy modification by pruning and training and is one of the most suitable for high density planting, as it bears fruits on current season's growth and responds to pruning (Figs. 6 a, b, c and d). Wide branch angles, producing a spreading tree are important to minimize the branch breakage when carrying heavy crop and to reduce labour input in guava tree shaping, particularly in high-density planting system. Control of apical growth must begin within first year of planting of guava continue each year in high-density planting system. Topping and hedging have been found to be valuable techniques in controlling tree size during initial stage (Fig. 5). Planting density of 3.0 m x 6.0 m (555 plants/ha) has been found most suitable and highly productive for Allahabad Safeda (6). However, HDP has been also developed for Allahabad Safeda which accommodates 5,000 plants/ha: (1.0 m x 2.0 m) coupled with regular topping and hedging, particularly during initial stage, are helpful in vigour control and extending fruit availability and yield per unit area (Fig. 7)(6). In young

Fig. 3

Fig. 4

Fig. 5 Fig. 3. High-density planting in guava. Fig. 4. Early shoot management for better production and

canopy shape. A, unpruned; B, pruned tree. Fig. 5. Initial canopy management, brings maximum shoots in fruiting, for better harvest under high-density planting system.

B

Approaches and Strategies for Precision Farming in Guava

vigorously growing trees the leading branches can be bent down and tipped to promote sprouting of laterals, which are capable of bearing profusely (Fig. 8).

Fig. 6. Concurrent shoot pruning has been found efficeint method for controlling tree size and better productivity under high-density planting. (a) Pruning for the initiation of new shoots, capable of producing flower buds; (b) repruning of new shoots when the fruits are 2-3 cm in diameter for initiation of new shoots; (c) new shoots emerging as a result of step (b) are also efficient in fruit producition; (d) reponse of topping and hedging (A) and unpruned row (B) under high density planting and (e) a portion of a tree showing several fruit-bearing shoots as a response of concurrent pruning.

(a) (b) (c) (d) (e) (d) B A

Fig. 7. Reponse of topping and hedging during initial stage for accommodating more number of plants per unit area.

Fig. 8. Bending of branches in guava tree can induce profuse flowering and fruiting.

Fig. 7

Fig. 8

Rejuvenation of Old Plantation

The old orchards which have turned unproductive and produce low grade fruits require a special attention. They should be rejuvenated through heavy and systematic pruning, followed by fertilization and plant protection measures. Heading back of unproductive guava trees (at the height of 1.5-2 m from the ground level) is done in the month of May followed by pruning of newly sprouted shoots below the cut point of parent stump in October has shown encouraging results (Figs. 9 a, b, c and d). The newly initiated shoots after 'October-cut' are found to be very conducive for flowering and fruiting in the following seasons.

Growth and Development

One of the critical characteristics of guava is that flowers are borne on newly- emerging lateral shoots, irrespective of time of year (11). Consequently, the occurrence of bloom and fruiting in the course of the year may be erratic or seasonal, depending on how the environment affects shoot growth. This characteristics allows the tree to be manipulated to crop when desired in a favourable climate. Defoliation/ pruning are the main methods to force the axillary bud to shoot (14). Presumably, the flowers are already differentiated before the side shoots emerge, implying that the lateral buds should not be forced to break before differentiation has been completed. Shoot growth is indeterminate under good growing conditions long vigorous shoots dominate, which suppress the emergence of flowering side shoots.

A load of fruits acts as strong sink to moderate extension growth and to delay the leafing out of lateral buds until after harvest. Good fruiting is therefore instrumental in establishing the desired pattern of shoot growth thereby regulating canopy size.

Approaches and Strategies for Precision Farming in Guava

Crop Regulation

There are two major flowering seasons, once during March-May, the fruits of which are harvested in rainy season (late-July to mid-October) and the other in July- August with the fruits harvested during winter (late-October to mid-February). Often a third crop is also noticed, from flower appearing in October and the fruits harvested in March (8). Among three flowering seasons, maximum fruiting occurs in rainy season (11). This is incidentally, the period when heavy rains are received and the wet-humid weather adversely affects quality while approaching the maturity stage. Various types of fungal diseases and attack of fruit fly are common. This crop is poor in quality, fruits are rough, insipid, watery and less nutritive. Rainy season fruits are also spoiled rapidly due to loss of glossy appearance with discolouration followed by blemishes, desiccation, loss of firmness, protopectin and vitamin 'C' after harvesting. As regards the net return in terms of cash, the winter season crop is more profitable than rainy season crop due to high selling rates and less damage to fruits by diseases and insect pests (13). Winter

(b)

(c)

(d) (a)

Fig. 9. (a) Rejuvenated (heading back) guava tree in the month of May (R) and unrejuvenated (UR) guava trees; (b) new shoots emerging on rejuvenated trees; (c) new shoots were pruned during October to induce new laterals capable of fruiting and (d) a close view of fruiting twigs as a result of pruning shown in (c). Source: Singh, Gorakh, PFDC, Lucknow

R UR

fruits have better storage life and can be transported over a long distance.

Orchard losses can be avoided by following simple and effective crop regulation practices by which guava trees can be made to bear and mature as regular winter crop of disease free fruit of very good quality (9 and 12).

The crop regulation studies confirmed the efficacy of spraying fertilizer grade urea in May to increase the yield of winter season crop (Figs. 10, 11 and 12). A crop regulation technology has been developed at CISH, Lucknow (10), wherein the inferior quality rainy season crop is eliminated by spraying twice with fertilizer grade urea (10 per cent) in Allahabad Safeda and in Sardar, during bloom (April-May). This resulted in increase of good quality fruits during winters by four times in Allahabad Safeda and three times in Sardar(7).

Fig. 10. Defoliation induced by fertilizer grade urea. Fig. 11. Fruit set on new shoots emerged as a result of defoliation. Fig. 12. Heavy winter crop as a response of defoliation through fertilizer grade urea

Fig. 11 Fig. 10

Approaches and Strategies for Precision Farming in Guava

Weed Control

Weed control is crucial during first 2-3 years of orchard establishment. After that, the trees provide adequate shade to minimize interference by weeds. Mulching with black polythene sheet or heavy mulching with organic material, such as, straw, dried grass, banana leaves, immediately surrounding the main trunk drastically reduces weed growth. Herbicides are generally not recommended in young orchards due to the possibility of causing severe damage by spray drift or direct contact. Herbicide such as, glyphosate may be applied by rope wicks or rollers saturated with the herbicide solution and wiped on the weeds.

Irrigation

The chief economic consideration, which encourages growers to go for guava cultivation is that, this tree does not suffer much if it is not watered during hot months. It is, however, observed that where the plantation receives better care and regular irrigation in early years, yield of fruits is heavier and fruits are of better quality than the trees, which are neglected, as it usually happens. Adequate moisture is required during vegetative growth and for optimum flowering and fruit development. Almost complete post set drop is observed during drought. In dry tropics, flowering is greatly influenced of water availability. To promote the development of the fruiting twigs, irrigate every 10-15 days in summer and about 25 days in winter should be given. During the rainy season, plants hardly require any irrigation. The care of the young trees consists in watering them regularly during the dry season. In regions, receiving 380-500 mm rainfall,