Everything you need to learn about the cultivation, production and growth of sweet pepper in greenhouse!
Sweet pepper (Capsicum annuum L.) is also popularly known as Capsicum in India and rarely bell pepper. It is a valuable solanaceous fruit vegetable with excellent prospectus both for the domestic and export market. It stands good potential as an alternative for greenhouse tomatoes. However, growing of capsicum is cumbersome compared to that of tomatoes, although it can fetch high price in the market, during the same period.
Climate and Soil Requirement for Sweet Pepper Cultivation:
Pepper is more sensitive to environment as compared to tomato. The optimum night temperature for quality fruit production is 18-21°C. When temperature falls below 16°C over a longer period, growth and yield are adversely affected. Sweet pepper can tolerate day temperature above 30°C, as long as night temperature is within 21-24°C range.
However, it is insensitive to photo-period and humidity (day length and relative humidity do not affect flowering). There are evidences that this crop requires very specific climatic conditions for flower bud differentiation, pollen tube growth, fertilization and fruit set, fruit and seed development although varietal differences to varying climatic conditions exist. High temperature and dry winds leads to excessive flower drop of resulting in poor fruit set.
Heavy and continuous rains during flowering and fruiting also result in flower bud drop and thus poor fruit set. Sweet pepper grows best on loam or sandy-loam soil with good water holding capacity. However, it can be grown on variety of soils, as long as they are properly drained. For successful pepper cultivation soil reaction (pH) should be between 5.5 to 6.8.
Selection of Varieties for Sweet Pepper Cultivation:
Sweet pepper yields vary widely depending on variety, therefore it is necessary to compare the yield potential of old and newly developed varieties/hybrids as well as their fruit quality w.r.t. size, shape and fruit colour. The fruits are of various shapes and sizes from small tapered or ball shaped ones to long cones and big round bells.
Thick fleshed ones are best for roasting and cooking, while the thinner ones are suitable for salad. Four lobbed square shaped fruits are generally preferred in high markets. These are available in various colours. Green and violet have strong flavour whereas yellow, red and orange coloured are milder and sweeter. White and purple varieties are also available in European countries for greenhouse cultivation.
Such varieties are very vigorous and plants can become as tall as 8-9 feet in one year under the protected cultivation. Dutch peppers are high rated but Israelis peppers have also shown potential and as such may be quite suitable for cultivation in north Indian plains. There are several varieties, which can be grown successfully under both protected and open field conditions.
The important exotic and indigenous varieties are as under:
European varieties – Mazurka (red), Fiesta (yellow), Torkel (red), and Parker (red)
Israeli varieties – HA 1195 (red), HA 1038, HA 988, HA 1931 and HA 1589
The important varieties available in our country for greenhouse cultivation are : Nun- 3020 (yellow), Nun-3019 (red), Bharat, Mahabharat, (both red), Golden Summer (yellow), Bomby (red), Orobellee (yellow), Indira (red), Heera (red), Tanvi (yellow), Jaimini (red), Boyaton (yellow), Pusa Deepti (red) and California wonder etc.
Soil Preparation, Nursery Raising and Planting for Growing Sweet Pepper:
After deep summer ploughings beds are prepared with the help of tractor rotavator. Greenhouse sweet pepper is grown under drip irrigation system. After preparation of beds, drip lines of 16: 2: 30 size (20 mm diameter of laterals, 2 litre discharge of water per dripper per hectare and 30 cm distance between two drippers) are laid on the beds and two drip lines are laid on each bed at a distance of 60 to 65 cm depending upon the bed size.
Sweet pepper nursery is raised on soil-less media under high-tech nursery raising system for raising healthy and virus free seedlings. Fresh and high quality virus free seeds should only be used for sowing. After sowing, the seeds must be covered with a thin layer (6 mm) of fine grade medium and watered with a fine spray.
The soil or the trays must be covered with glass or plastic to avoid drying out. The optimum temperature for germination is 24 – 25°C. The young seedlings require good light conditions. After germination the covering material is removed and the temperature is lowered to 23°C.
The nursery is ready in 30 days for transplanting. Seedlings are transplanted at a distance of 60 × 30 cm. Around 4200-4300 seedlings are required for planting in 1000 m2 area of greenhouse. Transplanting should preferably be done in the evening and the nursery must be sprayed with systemic insecticides like confider or metasystox @ 0.5 ml per litre of water before taking it out from the nursery greenhouse for protecting the plants from post transplanting infestation of leaf curl virus.
The optimum temperature after planting is 22/21°C (day/night) on the first day, and 23/22°C later. Air humidity is best around 80 per cent. The root zone temperature is very important and should be around 22°C. Lower root temperature increases the risk of Pythium, while too high root temperature will cause too much growth and insufficient flower production.
Training and Pruning of Sweet Pepper:
Pepper plants initially develop single stem and after 9-13 leaves, a terminal flower develops where after main stem divides into two. Sometimes three or four shoots develop naturally rather than two. Also two flowers may develop rather than one. The flower in the first branching is a crown bud. The terminal flower is not allowed to develop into fruit and it is removed just after appearance.
Two main stems are maintained on each plant after pruning or pinching the other branches by leaving two leaves and one flower at each internode. These two stems are trained upon strings to the main wire running on row length at 8-9 feet height. The stems are either loosely trellised or bound around the strings. The stems are clipped with strings using rings or plastic clips.
The plant will continue producing terminal flower and two side shoots at every internode of every two new shoots, one is retained to continue the stem, and the other one is removed or just pruned by leaving one flower and two leaves. Three leaves are left on side shoots when the plant needs extra leaf area, either for better photosynthesis or for shading the fruit. In older plants, the pruned side shoots will carry the fruits.
Training and pruning should be done every three or even two weeks during the period of fast growth. The crop can grow up to 8-9 feet in height in 9-10 months period and after that the plants are topped to avoid stem breaking and to improve fruit size. Training and pruning work is highly technical and it should be done by the trained person only.
Fertigation in Sweet Pepper:
Drip system of irrigation is generally followed for greenhouse sweet pepper growing so as to maintain constant growth. The quantity of water required for pepper irrigation completely depends upon the crop growth stage and climatic conditions. The irrigation should be given at weekly interval during September and October. However, this interval is increased to 10-12 days during winter season which may continue till first or second week of March.
Where-after this interval is reduced to a week up to April and then twice a week irrigation is done during May and June. Fertilizer application with irrigation in liquid form is called “fertigation”. Optimum supply of nutrients is essential for high production of peppers. Among the fertilizers, N: P: K solution in the ratio of 5: 3: 6 is prepared for application in the pepper crop.
For drip fertigation ammonium nitrate, potassium nitrate and phosphoric acid are used as source of nitrogen, potash and phosphorus, respectively. Calcium deficiency may cause a problem of blossom-end rot in pepper, therefore, calcium fertilizer in the form of calcium nitrate should be applied with other fertilizers to correct the calcium deficiency.
Deficiency of micro-nutrients is also commonly observed in pepper and mostly three microelements viz., magnesium, zinc and iron are more prevalent. Their deficiency can be corrected by application of magnesium sulfate, zinc sulfate and chelated iron with the fertilizer solution. Ready-made liquid nutrient solution spray on the standing pepper crop is also beneficial.
Pollination in Sweet Pepper:
Pepper is a predominantly self-pollinated crop, however cross pollination does take place when activity of honey bees, thrips and other insects is high which transfer pollen from blossom to blossom while collecting nectar. Pollination is neither markedly improved by using an ‘electric bee’ nor by spraying plant hormones, but it is certainly in the presence of better honey or bumble bees fly. The number of seeds per fruit are, thus, more and fruits enlarge faster due to accumulation of more assimilates.
Inducing Fruit Set:
Fruit set will takes place automatically when the light is proper. The most practical way of facilitating fruit set is by dropping the night temperature to 18°C. The day temperature can stay at 20-22°C, but if fruit set needs further adjustment then the day temperature can also be dropped to 18°C.
The root temperature around 18°C gives more flowers. Very low night temperature (10°C) ensures a high percentage of fruit set but induces fruit with a few seeds only, which will abort or remain small. The night and root temperature around 18°C is optimum for fruit set.
Other way of inducing the fruit set is by increasing the CO2 concentration (700-1000 ppm). Day temperature and light are not so important for pollination itself, but high light and low day temperature are beneficial for setting and first growth of the new fruit. Fruit set takes about a week and is, normally, completed in 5 to 8 weeks after planting.
Fruit Load and Fruit Growth:
Sweet pepper can hold fruits only up to certain extent as excess of fruit load may cause decaying of roots. The number of fruits on a plant depends on light, temperature and plant size. Young plants can support 10-12 fruits per m2 under poor light conditions and over 20- 24 fruits per m2 under good light conditions.
About 5-9 weeks after fruit set, the fruit will reach its full size and 3-4 weeks later attain full colour, if coloured fruits are to be harvested. The total period from bloom to coloured fruit is 7-12 weeks. The huge variation in fruit growth duration is due to many factors like season, light, temperature, fruit load, condition of the plant, crop management and variety grown.
Harvesting and Storage of Cultivated Sweet Pepper:
Fruits of greenhouse cultivated sweet pepper are harvested only when they have attained full colour and are still firm. Green peppers require about 40-42 days to develop from pollination to mature green fruit; a further 14-21 days are needed for a fruits to reach red or yellow stage depending upon the temperature.
Best colour development takes place between 18 to 24°C irrespective of whether the fruits are on the plant or in storage. Capsicum fruits must be harvested with a very sharp knife or scissor to get a smooth stem end cut minimizing, thereby, damage to other fruits. It is desirable to start harvesting of fruits early in the morning and to finish before the hottest hours of the day.
Harvesting, handling and packaging should be done with the utmost care as capsicum fruits are very prone to handling damage. As the plants reach fruiting stage, fruits mature in flushes initially. However, during peak period frequent harvesting is needed. Coloured fruits are harvested once or twice a week, whereas, green fruits once in a fortnight.
Since pepper is a non-climacteric fruit, therefore, foliar spray of regulators like ethril is not effective in hastening ripening process. Ethril can lead to defoliation and hence, not recommended for the production of coloured peppers. As soon as peppers are harvested they should be hydro-cooled to remove field heat quickly.
The harvested fruits should be stored at 8-10°C and 90-95 percent relative humidity. Under these conditions they can be stored for 15-20 days. If fruits are stored at temperatures between 0°C and 8°C, pitting and blackened spots becomes visible on the flesh due to chilling injury. Waxing of pepper fruits before shipping is a common practice to check moisture loss and bruising during transit.
Yield of Sweet Pepper:
On an average sweet pepper varieties can produce 60-70 tonnes of coloured fruits and 100 to 120 tonnes of green fruits per hectare under greenhouse conditions. Although, yield is directly depended upon the variety, climatic conditions and crop management practices followed but average weight of a quality coloured four lobbed fruit is 180 to 220 g.
Sweet Pepper Plant Protection:
Sweet peppers are susceptible to the various aphid and mite transmitted viruses mainly tobacco mosaic virus (TMV), pepper mottle virus (PeMV), potato virus ‘y’ (P.V.Y.) and cucumber mosaic virus (CMV). TMV can be mechanically transmitted in peppers if TMV contaminated tobacco products have been handled earlier.
For this reason, the greenhouse labourers are not allowed to smoke or chew tobacco while handling pepper plants inside the greenhouse. There is no control for most of these viruses but by controlling the vector virus spread can be checked. Normally, planting of resistant varieties is the best way to control viruses.
If the variety is not having resistance then the crop should be planted when the pest pressure is lowest in open field cultivation, but in greenhouse cultivation with the use of anti-virus nylon net all around the greenhouse structure, it is not possible for the insects to make their way inside.
Since mites create several problems for successful cultivation of the crop, so regular monitoring and timely control of the mites is the best way for growing healthy sweet pepper crop in greenhouses. Mites can be controlled by spraying metasystox, endosulfan or dicofol @ 2.0 ml per litre of water at an interval of 5-6 days during peak infestation period.
Spray of miticide can also be done at 10-15 days interval to check mites. Care should be taken that these pesticides are sprayed either early in the morning or late evening to avoid any phytotoxic effect on the crop. Yellow and blue sticky traps are also used to catch white flies, aphids, thrips and other insects as a prophylactic measures.
Among the fungal diseases, powdery mildew is sometimes extremely destructive causing quick defoliation of the plants. Any sulphur fungicide like karathane, sulfex etc. can be used to control the disease. Normally, crop rotation is quite effective in reducing insects and diseases. For the control of root rot or damping off of seedlings, high quality pathogen free seeds should be used and always virus free healthy seedlings should be transplanted inside the protected structure.