Rice is the staple food for over 70% of Asians, the majority of whom are living below the poverty line. More than 90% of the world’s rice is produced and consumed in Asia (Barker et al., 1999) and rice production must be increased by an estimated 56% over the next 30 years to keep up with population growth and income-induced demand for food in most Asian countries where about 75% of total rice production comes from irrigated lowlands (Maclean et al., 2002). Almost 25% of the world’s rice is grown under rainfed lowlands and frequently affected by uneven rainfall distribution. Another 13% of the rice area under cultivation is always subjected to water stress during the growing season (Bouman et al., 2007). Food security in Asia and the increasing scarcity of fresh water resources for agriculture in many areas are stimulating the development of aerobic rice production system (Tuong et al., 2005).

Analysis of variance showed significant differences among the parents and hybrids for all the 19 traits studied. The line×tester interaction was significant for all the characters studied (Table 1; Table 2). The results of correlation analysis given in the Table 3 revealed that single plant yield exhibited positive and significant association with panicle length, harvest index and proline content. This was in conformity with the findings of Jayasudha and Deepak Sharma (2010) for harvest index and Michael Gomez and Rangasamy (2002) and Yogameenakshi et al (2004) for proline content.

Table 1 Analysis of Variance of RBD for different biometrical traits

Table 2 Analysis of variance of RBD for different physiological traits

Table 3 Phenotypic correlation coefficients between single plant yield and component characters

Even though grain yield under stress is the primary trait of selection in breeding programme for drought prone environments, low heritability of yield necessitates an alternative approach such as selection of secondary and putative traits. The inter correlation between yield contributing characters may affect the selection for component traits either in favourable or unfavourable direction. Days to 50 per cent flowering showed positive and highly significant association with filled grains per panicle as reported by Yogameenakshi et al (2004). Similarly positive and significant relationship was observed between productive tillers per plant and 100 grain weight. Similar results were reported by Anbumalarmathi and Nadarajan (2008). Panicle length had positive and significant association with harvest index, proline content, dry root weight, root: shoot ratio and single plant yield. This is in conformity with the findings of Vinothini and Ananda Kumar (2008). The trait, spikelet fertility showed positive and significant association for root dry weight and root: shoot ratio. This is in accordance with the reports of Malarvizhi et al (2010).

Yogameenakshi P., Nadarajan N., and Anbumalarmathi J., 2004, Correlation and path analysis on yield and drought tolerant attributes in rice (Oryza sativa L.) under drought stress, Oryza, 1(3/4): 68-70