Three species of rice stem borers occurred in Tamil Nadu, of which yellow stem borer (YSB), Scirpophaga incertulas (Walker) was more predominant than pink stem borer (PSB). Sesamia inferens, (Walker) dark-headed borer (DSB), Chilo polychrysus (Meyrick) in both Kar (June-September) and Pishanum (Oct-Jan) seasons. The PSB was second most numerous (35.21%) in Kar and was relatively as abundant as YSB in Pishanum (48.43%). The DSB was less common during either season (4.29-7.18%). Varieties had variable compostion of stem borer infestation. The YSB infestation was more from early tillering to maximum tillering stage, decreasing gradually with increasing PSB infestation from flowering stage. YSB was the most common species in all districts. PSB was more abundant than DSB in Coimbatore, Tanjore, Tuticorin, Madurai and Dharmapuri districts, whereas DSB was more numerous in Tirunelveli, Kanyakumari and Vellore districts.

Six inbred parental genotypes and their 30 F1 hybrid (direct and reciprocals) combinations were used to elicit the information on inter-relation-ship between 10 yield determining characters and their association with fruit yield during summer 1988. Fruit yield/vine showed significant positive correlation with average fruit weight, number of fruits/vine, harvest index, number of seeds/fruit and LAI on 60th day of sowing.

Six inbred parental genotypes viz., Pudur-2 (P1), Honey Island Yellow Flesh (P2), Asahi Yamato (P3), Sugar Baby (P4), Maruthamalai-I (Ps) and H.W.I (P6) representing a wide geographic diversity selected for this study were obtained from various sources and were used for the experiment.