Cultivation of Capsicum or Bell pepper or Sweet pepper (Capsicum annuum)

Introduction 

Capsicum can be grown successfully both in summer and winter up to an altitude of 2,000 above msl. It requires a long and moderate climate for 4 to 5 months. It is planted in May-June onwards in the hills, February-June/July in northern plains, March-April in parts of Maharashtra, and from June to December in Karnataka. It is possible to raise capsicum during summer under shade nets. It cannot withstand heavy rains during flowering or fruit sets.

Capsicum can grow best between 21-24°C. Ideal temperatures for flowering are 26-28°C day and 16-18°C at night. When temperatures fall below 18°C or exceed 27°C for extended periods, growth and yield are usually decreased. Very cold temperatures (<12°C) during the night also hamper growth and fruit set. Capsicums are photo-period and humidity insensitive (day length and relative humidity do not affect flowering or fruit set).

Although a wide range of soils is suitable it grows best in red or sandy loam soil with good water-holding capacity. Soil pH of 5.5-6.8 is ideal for capsicum cultivation. Water stagnation is detrimental to the crop. High acid soils need to be reclaimed using lime. Liming can be done by the use of calcium oxide, calcium bicarbonate, or dolomite.

Capsicum has a bidirectional root system, therefore there must be free unhampered root growth and root aeration for successful crop growth. While very heavy soils may pose problems in irrigation management and in keeping the surface loose. Capsicum cultivation on light soils with a proper management strategy can result in good crop yields.

Varieties

Capsicum yield varies widely depending on the variety. Growing capsicum in a different season or under a different rotation system might provide higher yields and/or higher prices. Practice relay or inter-cropping that might provide extra income from the same unit of land with reduced insect and disease problems.

Open-pollinated capsicum still dominates the market but more recently a number of hybrids have become popular among the growers. Open-pollinated varieties are Arka Mohini, Arka Gaurav, Arka Basant, California Wonder, PRSM 1, and Pusa Deepti, Bharat, Mahabharat, Bull Nose, Indra, Orobelle, Manhattan and Green Gold are popular hybrids.

Cultivation

Sowing and seed rate 

Quality seed ensures good, uniform, and rapid germination, and vigorous growth, resulting in good yield. Approximately 250-300 g seed is required to plant 1 ha area at a density of 30,000 plants/ha. About 1 g contains approximately 125 seeds. Seedlings are grown on raised nursery beds or in seedling trays, 7.5 m long, 1.2 m wide and 15 cm high. Keep at least 50 cm distance between two beds. The area earmarked for the nursery is first subjected to sterilization/fumigation to get rid of pathogenic fungi and bacteria. Solarization is done by covering the area with plastic or polythene sheets and sealing the sides so that the heat kills the microbes. The dug-up portion is treated with 0.5 liters of 40% formalin/m² and immediately covered with a plastic sheet for about 48 hr. After a gap of 5-6 days sowing can be made. Pre-drench with Captafol (0.2%). Well-decomposed farmyard manure (FYM) is mixed with topsoil @ 3 kg/ m². Fertilizers are mixed @ 0.5 kg of 15:15:15 mixture of NPK/bed. Seeds are sown in rows 7.5 cm apart and more than 1 cm deep.

If the seedlings have been grown in shade, harden them off by gradually exposing them to direct sunlight for 4-5 days before transplanting. On day one, expose them to 3-4 hr of direct sunlight. Increase the duration until they receive full sun on day four. Hardening is done by reducing the quantity and frequency of watering during the last week in the nursery so that these can withstand the transplant shock better.

Under good conditions, seedlings are ready for transplanting four weeks after sowing. An ideal seedling has 4-5 true leaves, is disease-free, stocky, and has no flowers. Transplant in the late afternoon or on a cloudy day to minimize transplant shock. Bury each plant to half its total height (root to tip), and irrigate immediately after transplanting to establish good root-to-soil contact. Transplanting can be done manually or by machine.

Commercially available plastic trays filled with sterilized pre-mixed media can be used to raise quality seedlings. Care should be taken to see that the bottom of each cell in the tray has a hole to ensure good drainage. Trays with a cell size of 1.5″ cm x 1.5″ cm are adequate. The trays need to be arranged in a greenhouse (may be improvised) where the temperature remains less than 30°C. After sowing, a drench of Captan (0.2%) is given. It takes 2-3 days longer when the temperatures are low. The nursery beds or trays are kept warm by covering them with dry grass or polythene sheets till the seeds germinate. Watering is done only when needed. The best is to keep the media continuously moist but not too wet. Fertilizer application is done through a mix of calcium nitrate and potassium nitrate @ 2 g each/liter of water applied twice and single superphosphate 10 g/liter (25-35 days) dissolved in hot water (2 applications).

Planting

 The seedlings are set to a depth up to the first true leaf. Its yield increases with planting density. Spacing depends on soil type, season, and variety. Spacing of 45 cm x 45 cm is ideal in Solan, and 50 cm x 30 cm in Bengaluru. For hybrids spacing of 80-90 cm, x 30 cm is adopted. Double row spacing gives higher yields. This is done by planting 2 rows in a bed with a 45 cm gap between them. The beds are separated 90-100 cm apart. The spacing within the row remains 30-45 cm.

About 42-45 day-old seedlings having 4-5 true leaves are ideal. The stem should be thick and may break when bent. It is essential that the soil is brought to a fine tilth before the ridges are formed. Planting is made on the sides of ridges of any convenient length. Upon earthing up on the 25th day, the plants will be in the center of the ridge. However, when planted under the drip system, the seedlings are set out in the center of the ridge with the drip line running alongside. Usually, a single row system is followed but a double row system has advantages, especially when the drip is installed. This system helps cut down drip costs and obtain higher yields. A single drip line in the middle of a double row can irrigate both the

Training and pruning

Capsicum grown outdoor is less exacting in terms of training and pruning compared with the greenhouse-grown crops. Under outdoor conditions, there is a tendency for the crown sets especially under stress conditions. To boost vegetative growth, fruit set and yield under such conditions, buds from the first and second nodes are pinched off. Unproductive branches below the first node are also clipped in cooler season especially when sun scald is not a problem. Tall growing hybrids need staking. This can be accomplished by using Gl wires strung across or thin bamboo or similar material tied to 3 feet stakes-placed at the ends of rows and tying the branches of plants loosely on these.

Manuring and fertilization 

Capsicum responds to high levels of nutrition. The farmyard manure @ 25 tonnes/ha is a prerequisite. Well-decomposed poultry manure is also beneficial. Neem-cake can be applied before planting. The quantity of fertilizers depends upon the soil type, variety, and season. For open-pollinated varieties, it should be 120:80:50 kg NPK/ha. For hybrids, it can go as high as 200:180:150 kg/ha.

A dose of 150 kg N/acre results in the highest yields when applied in 3 split doses (basal, 30-60 days after transplanting). California Wonder yields highest at 180 kg N and 50 kg P₂O,/ha. The highest total seed yield (85 kg/ha) and seed recovery in all 3 pickings are obtained with 200:112.5:75 kg NPK/ha.

Nitrogen (N) can be split into as many as 4 doses. For open-pollinated varieties, one-third to half N and full doses of P and K are applied as basal and the rest of N as a top dressing. With high doses for hybrids, N is split into 4, P into 2, and K into 3. The high mobility of N and K makes it imperative that these are applied as splits. The pre-plant dose is applied in bands in rows, covered with soil, and profusely irrigated prior to planting. With the availability of soluble fertilizers that can be injected into the drip system, there is a better utilization of nutrients resulting in good plant growth and uniformity. Nitrate form of N is preferred to ammonical form. Phosphorus is applied as single superphosphate and potassium as muriate of potash.

Excess of N along with intermittent water stress can result in blossom-end rot of fruits. This is seen as a water-soaked area near the blossom end. This later becomes light brown and leathery in appearance. The fruits turn rapidly red. The application of calcium (calcium chloride 2% spray) can obviate the symptoms. Phosphorus should be applied in the root zone and banding is better than broadcast. The N and K should also be applied in the root zone at appropriate intervals. While employing the drip system for irrigation, care should be taken while applying fertilizers along the drip line after opening the soil. Excess water is necessary after each top-dressing.

Aftercare

Capsicums require more care and attention than most other vegetable crops to get maximum yield. The soil has to be maintained in loose friable conditions without allowing the formation of crust. Any intercultural operation should ensure that the roots are least disturbed. Root pruning during cultivation can also cause blossom-end rot. Earthing-up is essential to prevent lodging of plants due to crop load. The plot should be kept weed-free. Hand-weeding and hoeing are the most common methods. However, Glycel can be sprayed 20 days before transplanting in the main field to control nutgrass.

Mulching with organic material, polyethylene plastic, or a combination of materials is recommended to reduce weed competition, soil compaction, and soil erosion, and maintain a uniform root environment, and conserve soil moisture. Most of the varieties require staking to prevent lodging, particularly when they have a heavy load of fruits. Integrated pest management should be followed. Use high-quality, disease-free seeds and/or seedlings, and remove diseased leaves and plants promptly.

Monitor fields at least twice a week for the presence of pests and diseases. Planting resistant varieties are the best way to control pests. Prevent plants from being overloaded with fruits. Remove routinely all fruits that are set at the first bifurcation node, and all leaves and branches below the first bifurcation node. Avoid crop rotation with solanaceous vegetables, because these crops share many soil-borne diseases.

Irrigation

Sweet peppers are fairly shallow-rooted and have a low tolerance to drought or flooding. They will generally wilt and die if they stand in water for very long, so drain fields quickly after heavy rain. The total numbers of irrigations required are around 15 with consumptive use of 442-450 mm. Maintenance of soil moisture potential below 0.65 bar either until fruits are picked or after it, significantly reduces the yield.

Thorough irrigation provides uniform soil moisture, essential for optimum plant and fruit growth. Over irrigation stimulates the growth of Phytophthora capsici. Furrow or drip irrigations are recommended; sprinkler irrigation should be avoided as wet leaves and fruits promote disease development, especially at night.

The furrow method is most commonly employed with the length of the rows 4 m or above depending on the slope of the land and type of soil. When water is not a constraint this method is preferred. The drip system is well suited to this crop. Uniform soil moisture and the friable nature of the soil are beneficial in terms of uniformity, good vegetative growth, and high yields with more grade A fruits. The third system is alternate furrow irrigation or irrigation in widely spaced furrows with double row planting that can help save water up to 40% in medium and heavy- textured soils.

Harvesting and post-harvest management 

Capsicum should be harvested when fruits reach full size and become firm, but before the color change (unless they are intended for mature color: yellow, orange, or red). The fruits at the first and second nodes will be larger than the subsequent fruits. It usually takes 35-45 days from flowering to the optimum harvest stage depending on the variety. For most sweet pepper varieties, production usually lasts 6-8 weeks (3-4 harvests as fruits ripen). The varieties give 5-6 pickings, while hybrids up to 12. In temperate regions, sweet pepper production is usually halted by the low temperatures at the end of the season. In tropical and sub-tropical regions, pepper productivity declines due to biotic and/or abiotic stresses. The reduction in fruit size over harvests is less in hybrids compared to varieties. The varieties yield 20-25 tonnes/ha and the hybrids above 45 tonnes/ha. While picking, the fruits are lifted gently off the plant without causing injury or breakage of the stem. Harvesting is done after 1 or 2 days of irrigation and picked fruits are kept in shade to avoid sun-scald. As soon as capsicums are harvested they should be hydro-cooled to remove field heat quickly. Capsicum can be stored at 20-22°C and 90-95% relative humidity for 2 to 3 weeks.