CROP PRODUCTION UNDER PROTECTIVE AGRICULTURE
Sumit Rajendra Salunkhe1 and Surendra Kumar Rai2
Several components have been introduced in the latest green revolution crop production technologies, so that it results in high yield crop production of improved variety. In agriculture sector, the use of new agro-chemicals and intensive crop cultivation techniques are adopted to boost the production. But for the past few years, periodical unabated explosions of whiteflies, bollworms, pod borers, defoliators, coccids, cutworms, plant hoppers etc., have emerged as direct disease transmitters and crop damagers in different regions of the world and have made agriculture less remunerative and highly risk prone. Without using any crop protection product or technique, the crop yields may be declined drastically. The entire effort of farmers and agriculture experts will be of no use in absence of crop protection techniques. This has aroused the need of crop protection techniques and products that can help to prevent the crop from damages and reduce the amount of risk involved in agricultural sector.
PROTECTIVE CULTIVATION TECHNOLOGY:
Protected cultivation practices can be defined as a cropping technique wherein the micro climate surrounding the plant body is controlled partially/ fully as per the requirement of the plant species grown during their period of growth. With the advancement in agriculture various types of protected cultivation practices suitable for a specific type of agro-climatic zone have emerged.
Followings are the various protective structures which are used to increase the crop production and quality of the produce.
- Net houses: These are used to reduce adverse effect of scorching sun and rains in vegetables, ornamentals and herbs.
- Plastic low tunnels: These are used to raise early nurseries of vegetables and flowering annuals.
- Green houses: These are framed structure covered with a transparent material in which crops could be grown under controlled environment. The environmental conditions refer to light, temperature, air composition and nature of root medium.
- Glasshouse: Glass is used as a Glazing material in the green house. Glass houses are fitted with the help of wooden or metal frame. The glass houses are constructed in all shapes and sizes and are quite effective for winter cultivation but due to increase in day temperature in summer, it becomes unfit for cultivation during summer. High initial cost, difficulty in construction and frequent damage of glass panels by strong winds has limited its use in both the regions. The variation in temperature between outside and inside conditions is 20 to 25º C.
- Gable Type: A number of wooden structures, constructed gable type, uneven span type and even span type structures are used in Kashmir valley and are covered with 200 micron ultra violet stabilized polythene. Generally wooden structure fabricated gable type greenhouses are predominant in the valley with an average size of 40 sq. m (4 x 10m).
- Gothic Type: Big size polyhouse is generally made of gothic type in Kashmir valley because the use of heavy iron structure which can sustain heavy snow load. The slope of the top layer is 300 and its side walls and central height is 1 m and 3.7 m respectively. Generally gothic type greenhouses are an average size of 120 sq. m. (6 m x 20 m).
- Walk in Tunnel: It is most popular type greenhouse which is small semi spherical structure frame made of materials like wood or plastic, iron , G.I. pipes and covered with polyethylene or fiber reinforced plastics. Maximum numbers of walk in tunnel type green houses have been installed in Kashmir valley region.. The various sizes of tunnel type green houses that were being utilized by the farmers and installed by different development departments are 40 sq. m (4 m x 10 m), 80 sq. m (5 m x 16 m) and 54 sq. m ( 9 m x 6 m).
- Ladakhi Polyhouse: The most common green house in the Ladakh region is the Ladakhi polyhouse. It is constructed by three side mud brick wall in place of polyethylene sheets which not only cuts down the installation cost but also reduces the adverse effects of strong winds and increases temperature retention in the green house. The polyhouse has three sides made of sun dried mud bricks. The back wall is 7 ft in height, while front has no wall. The average length of the poly house is 32 ft. with a width of 16 ft. The polythene is supported on wooden poles and side walls.
- Trench: This is a very simple, cheap and common green house structure especially for the Ladakh region of the state and, thus, has unlimited potential in the region. The various sizes of the trenches are (9 x 3 x 0.9 m) and (10 x 4 x 1 m) respectively. In this pit type of structure, wooden poles are used to hold UV stabilized polyethylene film. The polyethylene is also covered by an additional polyethylene film or woolen or cotton sheet during night to reduce heat loss in extreme winter.
- FRP Greenhouse: The glazing material used in the green house is fiber reinforced polyester. The normal dimensions of the green house are (30 x 9 m) with a centre height of 3.04 m and a side height of 1.82 m. The initial cost required for fabrication of the greenhouse is high but the comparative life of the green house is much more than other.
- Double layered Polycarbonate Greenhouse: The glazing material used in the green house is double layer polycarbonate. The normal dimension of the green house is 16.8 x 9.1 m with a center height of 3.3 m and a side height of 1.8 m. The variation in temperature between outside and inside conditions is 20º C.
- Polyench Greenhouse: This type of green house combines the trench and green house technology for achieving more temperature inside green house during peak winter. The glazing material utilized in the green house is polyethylene, FRP, double layer and triple layer polycarbonate. The normal recommended dimensions of the green house are (18 m x 4.5 m x 0.8 m).
- Solar Polyhouse Drier: Field Research Laboratory (DRDO), Leh has designed and developed a low cost non-conventional zero energy based solar polyhouse drier for scientific and hygienic dehydration of surplus fruits and vegetables like apricot, apple, cauliflower, cabbage, tomato, etc. when there is a glut in the market and to facilitate its availability during the snow bound winter. The drier works on the principle of greenhouse effect where it traps the solar radiation and maintains the temperature inside between 55-69o C. Provision has also been made for removal of hot and moist air from the chamber. It reduces drying period by 40 – 50 % as compared to sun drying.
Protective cultivation in temperate- dry areas:
Poly houses are made of local wood and polythene sheets. These are used for increasing growth period. Mulching is also an important area in view of high transpiration and low availability of moisture. Black alkathene mulch proved superior and increased cabbage yield.
Hi- Tech Protective Cultivation:
Hardening units for tissue cultured plants: Hardening of tissue culture raised plants is very crucial for successful field transfer. The commercially multiplied tissue culture plantlets of ornamentals, fruits, species and vegetables are hardened in green house undercongenial environmental conditions before planting them in open fields.
Transgenic green houses: Development of transgenic plants having industrial, economic, pharmaceuticals, nutritional and environmental importance is need for sustainable production in near future. The transgenic need is to be introduced with cautions in hills and mountain region.
Hydroponics: It allows growing if plants in nutrient solutions with or without use of an artificial medium. High economic value crops are grown in hydroponic systems.
Aeroponics: It is the modified formof hydroponics wherein nutrient mist is provided periodically at plant roots. This technology may have applications in Himalayas.
Green house technology: Green house is the framed or inflated structures cover with transient material large enough to grow crops under partially or fully controlled environmental conditions to get optimum growth and productivity.
Types of greenhouse/polyhouse
1. Low-cost greenhouse/polyhouse:
The low cost polyhouse is a zero-energy chamber made of polythene sheet of 700 gauge supported on bamboos with sutli (ropes) and nails. It will be used for protecting the crop from high rainfall. Its size depends upon the purpose and availability of space. The structure depends on the sun for energy. The temperature within polyhouse increases by 6-100C more than outside. In UV stabilized plastic film covered pipe framed polyhouse, the day temperature is higher and night temperature is lower than the outside. The solar radiation entering the polyhouse is 30-40% lower than that reaching the soil surface outside.
2. Medium-cost greenhouse/polyhouse
With a slightly higher cost, a Quonset-shaped polyhouse (greenhouse) can be framed with GI pipe (class B) of 15 mm bore. This polyhouse will have a single layer covering of UV-stabilized polythene of 800 gauge. The exhaust fans are used for ventilation. These are thermostatically controlled. Cooling pad is used for humidifying the air entering the polyhouse. The polyhouse frame and glazing material have a life span of about 20 years and 2 years, respectively.
3. High cost greenhouse/polyhouse
It is constructed on the structure (frame) made of iron/aluminum structure, designed domed shaped or cone shaped (as per choice). Temperature, humidity and the light are automatically controlled as per requirement of the users. Floor and a part of walls are made of concrete. It is highly durable, about 5-6 times costlier, required qualified operator, proper maintenance, care and precautions while operating.
The low and medium-cost greenhouses have wide scope in production of domestic as well as export-oriented vegetables. NEH region recorded highest rainfall in the world. The duration of rainy season is also wide (April-October). During this period, growing of vegetables such as cabbage, cauliflower, broccoli, tomato, brinjal and French bean in open conditions is very difficult. Severe attacks of pest and diseases occur due to heavy rains. So, growing of vegetable crops in low cost polyhouse during this period is very profitable. Control of disease and pest in polyhouse is also easy.
Benefits of Greenhouse:
1. Vegetable forcing for domestic consumption and export.
2. Raising off season nurseries.
3. Productivity is manifold in greenhouses in comparison to growing the vegetables in open field.
4. Vegetable seed production.
5. Hybrid seed production.
6. Maintenance and multiplication of self incompatible line for hybrid seed production.
7. Polyhouse for plant propagation.
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Sanwal, S.K. Patel, K.K. and. Yadav, D.S (2004). Vegetable production under protected conditions in NEH region: problems and prospects. ENVIS Bulletin: Himalayan Ecology 12(2).
Shahi, N. C. (2009). Protective Cultivation- A Key for Sustainable Production in North Western Himalayas. http://www.agropedia.iitk.ac.in
Sumit Rajendra Salunkhe1 and Surendra Kumar Rai2
1 Research fellow, Dept. of Extension Education, NMCA, NAU, Navsari- 396 450
2 Research fellow, Dept. of Extension Education, NMCA, NAU, Navsari- 396 450