Evaluation of Discriminant Analysis in Identification of Deep and Shallow Rooted Plants in Early Segregating Generation of Rice (Oryza sativa L.) Using Single Tiller Approach

Indirect selection for deep-rooted rice varieties via shoot-related traits could help the breeder in identifying drought tolerant lines. This study was conducted to determine the effectiveness of discriminant analysis in recognizing deep-rooted types of rice on the basis of a few plant measurements. The F2 population was divided into two groups based on maximum root length of the female deep-rooted parent ʹMoroberekanʹ. Mean performance of deep-rooted group was always higher than the shallow-rooted group for all the traits. The most important variable for discriminating between the two groups was shoot dry weight followed by plant height and days to 50% flowering. These three characters together were explained about 25.1% of the variability between two groups. The discriminant coefficient for shoot dry weight was approximately four times more than the magnitude relative to plant height. By mean of shoot dry weight, plant height and days to 50 % flowering as predictors, 78.6% of the observations were correctly classified into their true groups as deep rooted lines. A 78.6% correct classification was the best achieved and was as good as that obtained with all 10 original variables in the analysis simultaneously. Three canonical variables were generated to find the optimal combinations of variables needed to discriminate between two groups. Canonical variable one had the highest correlation with shoot dry weight followed by plant height. To confirm the result, 89 F2 deep-rooted lines were forwarded to next generation and evaluated for root length in the same way. Out of that 76.4% of the F2:3 population were deeper rooted than the Moroberekan parent and was not significantly different from the expected result. These results show that discriminant analysis may be an efficient and useful tool for predicting the deep-rooted genotypes on the basis of a few plant measurements that are routinely assessed by breeders