CO(R) 49: A High Yielding Medium Duration Fine Grain Rice Variety for Tamil Nadu

Medium duration rice culture CB 99019, a derivative of the cross C 20 / RNR 52147 was released as CO(R) 49 during the year 2008 as an alternative variety for BPT 5204. CO (R) 49 is a semi dwarf, non lodging erect plant type which matures in 135 days. In the overall analyses of 110 yield trials conducted for six years in different locations, it recorded a mean grain yield of 6041 Kg ha -1 which was 6.5 per cent increase over BPT 5204. It is moderately resistant to stem borer, GLH, blast and RTD. It has medium slender white fine rice with an L/B ratio of 2.79 variety. Variety CO(R) 49 has superior cooking quality with intermediate amylose content (23.25%), soft gel consistency and moderate gelatinization temperature. The variety with higher yield, better pests and diseases resistance and superior cooking quality in comparison to the checks, IWP and BPT 5204 is suitable for cultivation during late samba / thaladi season in Tamil Nadu.

Rice is the predominant crop of Tamil Nadu that occupies about 30% of the total cropped area. At 2015 the area under rice will be around 19 lakh ha and the production 71 lakh tonnes at an annual growth rate of 4%. During the current year rice occupied 18.45 lakh ha with a production level of 56.65 lakh tones (www.tn.gov.in/dept/agriculture/ pdf). Major challenge is to develop rice varieties with a quantum jump in the yield over that of existing rice varieties. (Bastia et al., 2010). High yielding rice varieties play an important role in increasing the production level. During late samba / thaladi season of Tamil Nadu medium duration rice varieties like CO 43, Improved White Ponni (IWP), BPT 5204, ASD 19, ADT 39 and ADT(R) 46 are grown by the farmers of Tamil Nadu. IWP and BPT 5204 are grown extensively for their superior grain quality. Rice grain quality has become an important issue associated with domestic consumption and marketing of rice. In Tamil Nadu, consumers prefer medium slender grain type with intermediate amylose content, moderate gelatinization temperature and medium gel consistency. The gelatinization temperature, gel consistency and amylose content are the major rice traits that are directly related to cooking and eating quality. The gel consistency is responsible for softness and amylose content is responsible for texture and appearance in rice (Hossein Sabouri, 2009). The quality in rice is generally considered from the view point of milling quality, grain size, shape and appearance, and cooking characteristics. The rice quality can be improved genetically through the improvement of grain quality (Abdus Salam Khan et al., 2009). Presently farmers are cultivating fine grain rice varieties viz., IWP and BPT 5204 which are susceptible to major pests and diseases and hence suitable variety for replacement is needed. Hence, the variety CO(R) 49 with high yield good cooking quality characteristics and pest and disease resistance is developed.

Results and Discussion
Culture CB 99019 was tested in station trial in thaladi season for six years at Department of Rice,  49 recorded an overall mean grain yield of 6041 Kg ha -1 which was 6.5 per cent improvement over BPT 5204 (Table 1).
Medium duration rice variety CO(R) 49 is semi dwarf (85-90 cm), erect with strong culm and well exerted panicle with duration of 135 days (seed to seed). Distinguishing morphological characters of this variety is given in Table 2. It has long, compact and droopy panicle with a length of 25-28 cm. The variety has 1000 grain weight of 15.9 g. CO(R) 49 variety has medium slender grain type with an L/B ratio of 2.79. It has good milling percentage (72.3%) and head rice recovery (68.3%) which is in accordance with Shivani et al.,(2007)   improved agronomic efficiency over both the systems. The recommended levels of fertilizer and the plant population for late samba/thaladi season rice variety hold good for this variety (Table 4).
The variety CO(R) 49 was screened against all the five major diseases viz., blast, bacterial blight, sheath rot, sheath blight and rice tungro disease (RTD) under field and artificially inoculated conditions during 2005-06, 2006-07 and 2007-08. It was moderately resistant to blast (score 5), bacterial leaf blight (score 5), sheath rot (score 5), and RTD (score 3). The variety was evaluated at Coimbatore, Madurai and Aduthurai against the major pests and was found to be moderately resistant to yellow stem borer (score 3), leaf folder (score 5) and GLH (score 3).
CO(R) 49 rice variety (CB 99019) with higher yield, pest and disease resistance with superior cooking quality in comparison to the check variety BPT 5204 was released during 2008 and it can be cultivated as a transplanted crop in late samba / thaladi season in Tamil Nadu.