Diseases and Management of Crops under Protected Cultivation

(Diseases and Management of Crops under Protected Cultivation)
Planning, Design and Construction of Poly House / Protected Structure
P. K. Singh
Department of Irrigation and Drainage Engineering, G.B.P.U.A.&T., Pantnagar- 263 145 (UK)
Protected cultivation practices can be defined as a cropping technique wherein the micro
environment surrounding the plant body is controlled partially/ fully as per plant need during their
period of growth to maximize the yield and resource saving. With the advancement in agriculture
various types of protected cultivation practices suitable for a specific type of agro-climatic zone
have emerged. Among these protective cultivation practices, green house/poly house cum rain
shelter is useful for the hill zones. The green house is generally covered by transparent or
translucent material such as glass or plastic. The green house covered with simple plastic sheet is
termed as poly house. The green house generally reflects back about 43% of the net solar
radiation incident upon it allowing the transmittance of the "photosynthetically active solar
radiation" in the range of 400-700 Nm wave length. The sunlight admitted to the protected
environment is absorbed by the crops, floor, and other objects. These objects in turn emit long
wave thermal radiation in the infra red region for which the glazing material has lower
transparency. As a result the solar energy remains trapped in the protected environment, thus
raising its temperature. This phenomenon is called the "Green house Effect". This condition of
natural rise in green house air temperature is utilized in the cold regions to grow crops
successfully. However, during the summer season due to the above stated phenomenon
ventilation and cooling is required to maintain the temperature inside the structure well below
35°C. The ventilation system can be natural or a forced one. In the forced system fans are used
which draw out 7- 9m 3 of air/sec/ unit of power consumed and are able to provide 2 air changes /
minute.
Why Protected Cultivation
The vegetables / any other produce harvested from the protected cultivation have better
quality in terms of the fruit size, per fruit weight, TSS, colour, texture and other quality
parameters.
The productivity of the crop under protected cultivation increases manifold (2-10 times) as
compared to conventional system.
Off-season cultivation of the vegetables/other crops is the most important aspect of
protected cultivation. The winter season vegetable crops such as cauliflower, coriander,
spinach etc can be grown during rainy season. Similarly, summer season vegetable crops
are successfully grown during winter and the winter season leafy vegetable can be grown
during summer.
Under protected environment the incidence of insect and disease are minimized due to its
isolation from open field. Use of micro irrigation and off-season cultivation also minimizes
the disease and insect incidence. Less infestation of insects and disease offer reduced use
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