1. APPLICATION OF SYSTEM OF RICE INTENSIFICATION (SRI)
PRINCIPLES IN SUSTAINABLE RICE PRODUCTION IN BHUTAN
Ngawang Chhogyel, Mahesh Ghimiray and Yadunath Bajgai
Introduction
Rice (Oryza sativa L.) is the most important food crop in Bhutan. Due
to reliance on rice for food, the Bhutanese government has identified
a number of interventions for sustainable production. One such
intervention is to promote the system of rice intensification (SRI)
modified for local conditions. The country’s production of just 78,730
tons with productivity of about 3.2 t/ha (DoA, 2012) is below global
average of 4.45 t/ha (FAOSTAT, 2013). SRI experiments conducted
elsewhere have reported mixed results. However, the proponents of
SRI claimed that the farmers are usually able to harvest yield of 7-8 t
ha-1, and with proper management practices, yields can go beyond 15
t ha-1 (Uphoff, 2007).Rice being the number one staple crop, it has
become a huge challenge for the Department of Agriculture to
enhance national rice self sufficiency (Chhogyel et al., 2014).
Therefore, this experiment was conducted to demonstrate and
promote variants of SRI principles in local production management
system and to reaffirm the performance of this technique as a
potential approach to yield maximization.
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Result and Discussion
The 2010 to 2013 SRI experiment results showed that the average
grain yield ranged between 4 -7 t ha-1 with about 22 numbers of
effective tillers hill-1. Similarly, the result from the 2013 experiment
which used 10 d and 15 d old seedlings gave an average grain yield of
5 t ha-1 (Figure 1).
Though the effects of seedling age on grain yield was not
significantly different, the values of root-shoot ratio were
significantly affected (Table 1). The younger seedlings exhibited
higher values of root-shoot ratio (0.174 - 0.198). The numbers of
productive tillers were also higher for younger seedlings.
Increased tillering and higher root-shoot ratio indicated higher yield
potential under minimum water and proper nutrient management.
There was a gradual decrease in grain yield with increasing seedling
ages. These findings corroborate with results obtained by Ginigaddara
et al. (2011), Uphoff (2002) and Geethalakshmi et al. (2008).
Rice under SRI condition avoids suffocation and degradation of plant
roots which is the main reason for improved plant performance (Kar
et al., 1974). Higher root shoot ratio under SRI condition is also
attributed to improved soil aeration supporting growth and
multiplication of soil organisms that provide multiple benefits to the
plants (Randriamiharisoa et al., 2006).
Figure 1. Grain yield among the three different seedling age
groups
Conclusion
As proven by a number of experiments in the past, SRI could be
one of the rice production technologies for the 21st century. SRI
could fit well for a small country like Bhutan, which is
characterized by small land holdings, and abundance of vegetation
cover for organic matter supply. It is possible to raise the current
yield ceiling of 3.2 t ha-1 by adopting some principles of SRI such
as planting younger seedlings and integrated nutrient and water
management. SRI principles offer opportunities to cope up with
emerging climate change issues and enhance water use efficiency.
It could help resource poor farmers who face water shortage
coupled with loss of soil quality and increasing costs of fertilizers.
Thus, increasing plants’ resilience to stresses such as drought with
less penalty on grain yield
References
Chhogyel N, Dorji C and Bajgai Y. 2014. Reaping the bounty of rice twice a year: In Sonam Drupdrey: Fruits of
Labour, an Annual RNR Magazine (4):27-28
Department of Agriculture (DoA).2012. Agriculture Statistics. Extension and Information management.
Departiment of Agriculture.MoAF, Thimphu Bhutan. 295p
Food and Agriculture Organization statistics (FAOStat).2013. Food and Agriculture Organization of the United
Nations. United Nations Development Program. http:///-faostat.fao.org/site/339/default.aspx. Accessed on July,
2014.
Uphoff N. 2007. Agro-ecological Alternatives: Capitalizing on existing genetic potentials. Journal of
Development Studies 43: 218-236.
Kar S, Varde SB, Subramanyam TK, Ghildyal BP. 1974. Nature and Growth pattern of rice root system under
submerged and unsaturated conditions. Il Riso (Italy) 23:173-179
Methodology
Young Seedlings
(10-15 d old)
FYM (3 t ha-1)
NPK (70:40:30)
2 hand weeding+
herbicide
Table 1. Plant response to different seedling ages
Treatment
Days to
flowering
No. of
productive
tillers hill-1
mean R/S
ratio*
10 DAS 96a 14.67a 0.174 a
15 DAS 87a 15.33a 0.198ab
20 DAS 76a 14.67a 0.128c
P < value 0.90 0.88 0.028
4th International Rice Congress, October 27 – November 01, 2014, Bangkok, Thailand