MSc

The present study on “Genotype x Environment interaction in aromatic rice (Oryza sativa L.) cultivars of Wayanad district of Kerala” was carried out at the Department of Plant Breeding and Genetics, College of Horticulture, KAU, Vellanikkara during 2010 - 2012 aiming to characterize the aromatic rice cultivars (Gandhakasala and Jeerakasala) of Wayanad district based on morphological, cooking and biochemical characteristics, to assess the magnitude of G×E interaction and to analyse the stability over different environments.

Gandhakasala and Jeerakasala are the most popular traditional aromatic cultivars of Wayanad district of Kerala. Out of the total 37 samples of aromatic genotypes collected from different areas of Wayanad district, eight Gandhakasala types and one Jeerakasala type were selected based on the grain characteristics like non pigmented apiculus, golden colour lemma and palea, white kernel colour, slender grains with partial awns (for Jeerakasala type) and awnless medium grains (for Gandhakasala type) and used along with check varieties for in depth study. These genotypes were evaluated at Wayanad and Idukki districts representing high altitude areas and at Palakkad district representing normal altitude area.

Aromatic genotypes when compared with check varieties recorded more leaf length, culm length, days to 50 per cent flowering, days from seeding to harvest, panicle length, number of productive tillers and straw yield at all the three locations. In aromatic genotypes, the total duration was nearly 30 days less at Palakkad than at higher altitude areas. High level of spikelet sterility was observed at Idukki district in all the genotypes. Hence, grain yield and grain characteristics could not be recorded at Idukki district. Among the aromatic types, Jeerakasala type recorded significantly higher grain yield and 1000 grain weight than Gandhakasala types at Wayanad and Palakkad. The aromatic genotypes had less milling recovery than check varieties at both locations, indicating the need for specially designed machines for milling aromatic genotypes. At Wayanad, Gandhakasala types recorded high kernel elongation ratio and low volume expansion ratio (preferred grain characteristics for aromatic rice) compared to Jeerakasala type and check variety.

In general, total carbohydrate content and protein content were low for aromatic types. The favorable characters of aromatic rice cultivars were more expressed at Wayanad district than at Palakkad district. At Wayanad, aromatic genotypes recorded low to intermediate amylose content. At Palakkad, all aromatic genotypes except GT 2 had low amylose content which can lead to stickiness of cooked rice. At Wayanad, most of the aromatic genotypes except GT 5 expressed moderate aroma. Whereas, at Palakkad the genotypes expressed slight aroma only, reducing its marketability. Grain length, 1000 grain weight, milling recovery per cent, amylose content and kernel elongation ratio were significantly high at Wayanad.

Short and partial awns were the characteristic features of Jeerakasala grains, while awns were absent in Gandhakasala types and check varieties. Aromatic genotypes had white seed coat colour, whereas check varieties had red seed coat colour. Unusually high spikelet sterility recorded for all the genotypes when grown at Idukki was a pioneer report of such phenomenon leading to total crop loss from Kerala. Fertile spikelets were recorded from Wayanad and Palakkad districts.

Studies on phenotypic and genotypic coefficient of variation revealed high level of variability for grain yield and 1000 grain weight and moderate level of variability for grain length, amylose content and protein content. Characters like leaf length, culm number, number of spikelets per panicle and straw yield indicated high heritability accompanied with high genetic advance at high altitude areas. Grain length and 1000 grain weight had significant positive correlation with grain yield. Whereas leaf length, culm length, days to 50 per cent flowering, days from seeding to harvest and panicle length had negative genotypic correlation with grain yield. At Wayanad and Palakkad, 1000 grain weight revealed high positive direct effect with grain yield.

At Wayanad, JT 9 (Jeerakasala type), GT 3 and GT 8 (both Gandhakasala types) showed better performance based on high grain yield, high straw yield, intermediate amylose content and moderate aroma. The aroma and amylose content in aromatic genotypes were low at Palakkad district, hence further studies are needed to find out the suitability of cultivation of aromatic types in Palakkad district.

Stability analysis for morphological characters recorded from three locations revealed that GT 6 had more adaptable characters over environments. GT 1 had more stable grain characters from recorded two locations. The predicted grain yield at Idukki was high for JT 9.