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The research work ‘Breeding for lodging resistance in rice (Oryza sativa L.)’ was conducted in the Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara, during the academic year 2017-2019. The research work was divided into three experiments. Experiment 1, consisted of screening of twenty-one rice genotypes for lodging resistance which was conducted at Agricultural Research Station (ARS), Mannuthy. After screening, three lodging resistant rice genotypes were selected and crossed in Line x Tester pattern with four lodging prone high yielding varieties, in experiment 2. In experiment 3, progenies were evaluated along with parents for lodging resistance. Lodging and other characters were measured based on Standard Evaluation System of Rice, developed by International Rice Research Institute (SES-IRRI), 2014.
Wide variability existed among twenty-one genotypes for yield and most of the yield attributes studied, indicating ample scope for the improvement through selection. High heritability coupled with high genetic advance as per cent of mean indicating the influence of additive gene action in the expression of trait were observed for all the traits viz., days to fifty per cent flowering, plant height, flag leaf width, flag leaf length, tillers per plant, internodal length, culm diameter, culm wall thickness, days to maturity, panicle length, panicles per plant, panicle weight, seeds per panicle, test weight, silicon content, potassium content, seed yield per plant, and lodging per cent.

Seed yield per plant recorded positive correlation at genotypic level with number of tillers per plant, number of panicles per plant, test weight, and silicon content. Lodging per cent exhibited positive correlation at genotypic level with days to fifty per cent flowering, plant height, flag leaf length, internodal length, culm diameter, days to maturity, and panicle length. At the same time, it was negatively associated with culm wall thickness, silicon content and potassium content.

Based on experiment 1, four genotypes viz., Swetha (L1), Prathyasha (L2), Vaisakh (L3) and Ponmani (L4) were selected as lines. Three genotypes viz., Uma (T1), Gouri (T2) and Pournami (T3) were selected as testers.

Evaluation of hybrids based on mean performance revealed that, hybrids H3, H5, H6, H9, and H12 recorded reduced lodging and H7, H8, H10, and H11 recorded moderate lodging.

Based on scoring, for all the characters, the hybrids H1 (L1 x T1), H3 (L1 x T3), H5 (L2 x T2), H7 (L3 x T1), H8 (L3 x T2), H10 (L4 x T1), H11 (L4 x T2), and H12 (L4 x T3) showed
high values.

Estimation of gca effects of parents indicated that, L4, T1 and T3 were better combiners for reduced lodging. Based on all eighteen characters, L4, T1 and T2 were found as better combiners. Considering the scores, of mean performance and combining ability effects for all the characters together, L4, T1, T2, and T3 were found as the most promising parents.
Specific combining ability effects studied among the cross combinations and scores indicated that, out of the twelve hybrids, H3 recorded high lodging resistance, and except H1 all others recorded moderate lodging resistance. Based on all the characters considered together, H1, H3, H5, H6, H8, and H10 recorded as better cross combinations. When scores of mean performances and sca effect were considered together for all the characters, hybrids H1, H3, H5, H8, H10, and H11 had high scores, and H6, H7, and H12 scored moderate scores.

All the twelve hybrids recorded high significant heterosis for days to fifty per cent flowering, plant height, days to maturity, internodal length and lodging per cent. Scoring for both mean performance and heterotic effect for all the characters, revealed that, the hybrids H12 recorded highest score followed by H10, H11, H8, H3, H5 and H1. Evaluation of hybrids based on scores of mean performances, sca effects and heterosis for all the traits, revealed that, hybrid H10 stands in first position, H8 in second and H11 and H5 in third position. Among these, H10 (Ponmani x Uma) and H11 (Ponmani x Gouri) were found as better cross combinations.

The identified hybrids can be evaluated in segregating generations for yield and reduced lodging.