Morphological and biochemical characterization of aromatic rice(Oryza Sativa L.) cultivars of Wayanad district of Kerala

Abstract

The present study was undertaken in the Department of Plant Breeding and Genetics and in the Centre for Plant Biotechnology and Molecular Biology, College of Horticulture, Ve!!anikkara and at RARS, Ambalavayal during 2008-2010 with an aim to characterize the aromatic rice cultivars of Wayanad district, based on morphological, nutritional and biochemical studies. Gandhakasala and Jeerakasala are two popular and traditional non-Basmati aromatic ricecultivars of Wayanaddistrict, Kerala. In Wayanad Gandhakasala is cultivated in an area of 327 ha, while Jeerakasala in 22 ha. Based on grain characters 10 samples of Gandhakasala and two samples of Jeerakasala were selected for characterization. Deepthi (WND.3) was used as check variety. Among morphological studies, qualitative characters like leaf bladepubescence, . panicle exsertion, spikelet awning, awn colour, lemma and palea pubescence and seed . . coat colour showed variation and hence these can be used as morphological markers to distinguish aromatic genotypes among themselves and with Deepthi. Straw coloured short and partial awns were the characteristic feature' of Jeer aka sa I a grains, while awns were absent i!1 Gandhakasala and Deepthi. Aromatic genotypes exhibited well exserted panicles and white seed coat colour whereas Deepthi showed moderately welIexserted . . panicles and red seed coat colour. Mean performance of aromatic genotypes indicated that ligule length, grain length, grain breadth, 1000 grain weight, days to 50 per cent heading, milling recovery and maturity days provided a good base for selection. Jeerakasala genotypes took more days to 50 per cent heading and to maturity than Gandhakasala genotypes and Deepthi . . In general Gandhakasala genotypes had lesser 1000 grain weight with a mean value of 13.78 gm compared to Jeerakasala (19;82 gm) and Deepthi (26.17 gm). High grain breadth and grain length would have added to high 1000 grain weight in Deepthi. In

general aromatic genotypes have lesser milling recovery than Deepthi, indicating the need [or specially designed milling machines for maximum milling recovery. The genotype GT2 appeared to have higher total carbohydrate content of 81.87 per cent/while it Was Iow for JT12 (58. 40%). Jeerakasala genotypes exhibited low mean carbohydrate content of 61.06 per cent' compared to Gandhakasala( 69.56%) and Deepthi (71.73%). The three Gandhakasala genotypes GT3, GT9 and GT7 exhibited intermediate proteincontent, indicating their nutritional superiority. The amylose content of aromatic genotypes ranged between 17.87(GT4) and 23.07 (GT2) percent. Five aromatic genotypes GT1, GT2, GT8, GTlO and JT12 had intermediate amylose content. Since intermediate amylose rice is preferred in most of the rice growing regions of the world, these genotypes will have better preference in market. Most of aromatic genotypes under study were moderately aromatic, indicating their suitability for commercial cultivation. Biochemical characterization based on isozyme studies revealed the possibility of utilizing peroxidase polymorphism for identifying the aromatic rice genotypes especially Gandhakasala genotypes from other cultivars. Studies on esterase. polymorphism revealed the presence of EST-2 band only in Deepthi indicating its use as a biochemical marker to distinguish aromatic rice genotypes from Deepthi. Heritability and genetic gain studies indicated that selection of characters like length of sterile glumes, lOOO grain weight, grain length and peroxidase activity may be effective in crop improvement programme. Correlation and path studies revealed that grain yield could be improved by simultaneous selection for high seedling height, grain breadth, milling recovery and straw yield.