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Protected Cultivation
Protected cultivation is defined as a cropping technique wherein the micro-
environment surrounding the plant body is controlled partially or fully as per the
plant’s need during its period of growth to maximise 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 protec-
tive cultivation practices, greenhouse or polyhouse is useful for the hill zones and net
house for hot areas for papaya cultivation. The greenhouse is generally covered by
transparent or translucent material such as glass or plastic. The greenhouse covered
with simple plastic sheet is termed as polyhouse. The greenhouse generally reflects
back about 43% of the net solar radiation incident upon it allowing the transmit-
tance of the ‘photosynthetically active solar radiation’ in the range of 400–700 nm
wavelength. 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 infrared 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 ‘greenhouse effect’. This condition of
natural rise of air temperature in greenhouse is utilised in the cold regions to grow
crops successfully. However, during the summer season due to the aforementioned
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 7–9 m^3 of air/sec/unit of power
consumed and able to provide two air changes/minute.
The use of protected cultivation for fruit crops, particularly papaya, has not been
adopted on the same scale as in vegetable- and flower-production systems. The chal-
lenges in producing this crop in protected systems are needed particularly where pest
and virus are the serious threats to quality and productivity. The objectives of this
chapter are to explore the concepts of protected agriculture as they apply to papaya
and illustrate the prospects for protected agriculture to address biotic and abiotic
challenges to fruit production.
17.1 Scenario
Besides sporadic efforts of Defence Research and Development Organization
(DRDO) in Ladakh, protected cultivation technology in India for commercial
production is hardly three decades old, whereas in developed countries namely,
Japan, Holland, Russia, the United Kingdom, China and others, it is about two cen-
turies old. In recent years, Israel is one country which has taken big advantage of
this technology by producing quality vegetables, flowers, fruits, etc. in water deficit
desert area for meeting not only its small domestic demand but also the huge export
demands. Recently, India has established collaboration with Israel for demonstration