Book of Extended summaries ISDA

International Conference on Reimagining Rainfed Agro-ecosystems: Challenges & Opportunities
during 22-24, December 2022 at ICAR-CRIDA, Hyderabad
cultivars with purple-coloured leaves will help in differentiating the weedy rice and other grassy
weeds from the direct sown rice. Rotation of rice with a dissimilar crop, such as corn, mungbean,
soybean and sesame, helps in disrupting the growth cycle of many problematic weeds, including
purple nutsedge (Cyperus rotundus) (Chauhan, 2013).
Similarity in terms of anatomical and physiological traits between rice and weedy rice makes the
herbicidal control of the weed difficult. Application of pre-emergent herbicides (pretilachlor,
metolachlor, oxadiazon) with appropriate modification in time and method of application is
advisable (Chauhan, 2013). The ‘KAU weed wiper’ is a device specially designed for the control
of weedy rice through the direct application of non-selective herbicides like glyphosate or
glufosinate ammonium on the earheads. The quick growth of weedy rice results in about 15-30
cm height difference between cultivated rice and weedy rice. This facilitates the easier
application of herbicides on the earhead of weedy rice without having any phytotoxic effect on
rice. It was reported that the weed control efficiency of weed wiper in terms of drying of weedy
rice panicles is as high as 83 to 88%. According to Suh (2008), herbicide resistant (glyphosate-,
glufosinate ammonium- and imidazolinone resistant) rice cultivars could be an effective tool for
farmers to improve weedy rice control with reduced costs.
Heavy infestation of weedy rice has forced many farmers to abandon their crops without
harvesting. The problem will worsen and become more persistent as direct seeding increasingly
becomes the popular method of crop establishment in rice. This may challenge the rice
production system in the country if not managed effectively in the subsequent years.
Awareness has to be created among farmers regarding the use of clean and uncontaminated seeds
and machineries. Future research should focus on the integration of cultural management
practices with the use of cultivars capable to grow in flooded conditions. Strong gelines for the
use of herbicide resistant rice cultivars need to be formed to avoid the development of resistance
in weedy rice through gene flow.
References
Chauhan, B. S., and Johnson, D. E. 2010. Weedy rice (Oryza sativa L.) I. Grain characteristics
and growth response to competition of weedy rice variants from five Asian countries.
Weed Sci. 58:374-380.
Chauhan, B. S. 2013. Strategies to manage weedy rice in Asia. Crop Prot. 48:51-56.
Chauhan, B. S., Abeysekera, A. S., Wickramarathe, M. S., Kulatunga, S. D. and Wickrama, U.
B. 2014. Effect of rice establishment methods on weedy rice (Oryza sativa L.) infestation
and grain yield of cultivated rice (O. sativa L.) in Sri Lanka. Crop Prot. 55:42-49.
683 | Page Resource conservation and rainfed agriculture