Previous Year Question
‘System of Rice Intensification’ of cultivation, in which alternate wetting and drying of rice fields is practised, results in
Reduced seed requirement
Reduced methane production
Reduced electricity consumption
Select the correct answer using the code given below:
1 and 2 only
2 and 3 only
1 and 3 only
1, 2 and 3
Correct Answer: D
Detailed Solution
The System of Rice Intensification (SRI) is not a separate variety of rice but a method of managing rice cultivation.
This method was developed in Madagascar during the 1980s. It aims to increase productivity through reduced seed and water requirements and better crop management.
SRI generally involves transplanting younger seedlings, planting one seedling at each location, wider spacing, avoiding continuous flooding and adopting mechanical weeding.
Statement 1 is correct: In SRI, generally only one seedling is planted at each location and the seedlings are transplanted at an appropriate distance.
It requires fewer seedlings and less seed than conventional dense planting. Proper spacing provides more room for the development of roots and tillers.
Statement 2 is correct: Continuously flooded rice fields develop oxygen-deficient anaerobic conditions.
Under these conditions, microorganisms decompose organic matter and produce methane. Methane is a powerful greenhouse gas.
Alternate wetting and drying under SRI increases the entry of air into the soil and reduces the anaerobic conditions responsible for methane production.
Therefore, methane production can be lower than under continuously flooded cultivation.
Statement 3 is correct: Since the field is not kept continuously flooded, comparatively less water needs to be pumped for irrigation.
A reduction in the requirement for pumping water also reduces the consumption of electricity or diesel.
Alternate wetting and drying supplies oxygen to the roots, improves their growth and enables plants to use nutrients more effectively.
The success of SRI depends upon the soil, availability of water, local climate, timing of transplantation and proper field management.
Therefore, reduced seed requirement, reduced methane production and reduced electricity consumption are all potential results of SRI. Hence, statements 1, 2 and 3 are correct.