COMBINING ABILITY AND HETEROSIS IN INTER-ECOTYPIC CLASSES OF RICE (Oryza saliva L.)

Abstract

An experiment of six-parent half diallel analysis on rice (Oiyu scuivo L..) was conducted to evaluate the combining ability and heterosis Ibr 14 yield and yield contributing characters. Seven AusxBoro cross combinations were found with encouraging higher cross compatibility and 131(21 XBRRI Dhan28 was the most compatible combination. The analysis oJ variances indicating the genotypes differed for all the traits studied. The ratio of (iCA and SCA variances for most of the characters revealed the predominance of additive gene action over non-additive. The Aus parents 13R21. 131(24. and 131(26 were good general eombiüers for days to 50% flowering and days to maturity. the Roro variety. BRRJ Dhan29 revealed good OCA effects for most of the important characters studied and BRRI Dhan36 for plant height, effective tiller plant'. panicle weight, number of primary branch paniclC'. 1000 grain weight, grain yield plant" and harvest index. Significant desirable SCA effects were estimated in the cross combinations 131(1(1 Dhan28xBRR1 Dhan36 (l3oroxBoro) for days to 50% flowering; and 13R2IxI3RRI Dhan29 (Ausxl3oro) for days to maturity. The Atlsxl3oro crosses BR2IxBRRI Dhan29. BR2lxlJRRl Dhan36. [3R24xI3RRI Dhan29 and BR26xBRRI Dhan29 were observed with considerable significant SCA effects and selected for grain yield plant and important yield contributing characters. Out of fifteen crosses, an AusxAus cross. 13R24x13R26 expressed desirable heterosis for paniele length. panicle weight and secondary branch panicle* BoroxHoro crosses. 13RRl Dhan29xl3RRl Phan36 and BRRI Dhan28xBRR1 Dhan29 were thvorah!y heterotie for days to maturity; I3RRI Dhan28xBltR1 Dhan36 for paniele length. secondary branch panicle". filled grain panicle4 and grain yield plant"; t3RTtl Dhan28xBRR1 Dhan29 and BRRI IThan28xBRRl Dhan36 for paniele weight; BRRI Dhan28xl3RR1 Dhan36 for grain yield plant'. The combination BR2IxI3RRI Dhan29 showed desirable heterosis for days to 50°/ flowering. days to maturity, grain yield plant" and harvest index; 13R2 I xl3RRl Dlian36 for plant height, panicle length. and grain yield plant': BR24x13RR1 Dhan29, BR26xI3RRI Dhan29 and BR2 I xBRRI Dhan28 for days to maturity.: 13R24x13RR! Dhan36 and BR26xI3RRI Dhan36 for paniele length. secondary branch paniele". number of filled grain panieW' and grain yield plant"; BR26xBI(RI Dhan29 for panicle weight: 13R24xI3RRI Dhan36 for thousand grain weight. For grain yield plant' the cross I3R26xBRRI Dhan36 was the best one followed by I3R26xBRRI Dhan29, I3R2IxBRRI Dhan36. BR24xBRRI Dhan36. and I3R2IxBRRI Dhan29. Combinations of BRRI Dhan29 and BRRI Dhan36 with other parents were better for overall performance. The cross combinations with good SCA and desirable heerosis should be further evaluated with standard check varieties Ibr their higher yield potentiality and earliness.