Combining ability and heterosis over environments for yield and yield components in two‐line hybrids involving thermosensitive genic male sterile lines in rice (Oryza sativa L.)

Abstract

Presence of substantial heterosis and economic hybrid seed production are two most desirable components for success of any commercial hybrid breeding programme. Thermosensitive genic male sterile (TGMS) lines of rice, in this regard, have tremendous potential in realizing further quantum jump in yield and economical hybrid seed cost. Analyses for combining ability and heterosis over optimum (120N : 60P 2 O 5 : 40K 2 O kg/ha) and high (200N : 90P 2 O 5 : 60-K 2 O kg/ha) fertility environments for six traits were made in 2 years (2001 and 2002) using 120 hybrids of inter-and intra-subspecific nature derived from hybridization of 30 elite indica TGMS lines and four cultivars, viz., ÔPant Dhan 4Õ and ÔAjayaÕ (I ¼ indica), ÔTaichung 65Õ (J ¼ japonica) and ÔIR 65598-112-2Õ (TJ ¼ tropical japonica) in line · tester mating design. Predominance of non-additive genetic variance suggested good prospects of hybrid breeding. Pooled analysis revealed highly significant variances for lines, general combining ability (GCA), specific combining ability (SCA) and line x tester. TGMS line 365-8S was the best general combiner for all the six traits including grain yield. Trend of relative mid-parent heterosis for grain yield, panicle length, grain number per panicle and earliness in flowering was I/TJ > I/J > I/I. For panicle number per plant and 1000-grain weight, trends were I/TJ > I/I > I/J and I/I > I/TJ > I/J, respectively. Grain yield recorded heterosis of 49.3%, 71.9% and 92.7% for I/I, I/J and I/TJ hybrid groups respectively. Effect of environments on the hybrid performance indicated better response of hybrids at high fertilizer dose. Study suggests greater prospects of combining improved japonica and tropical japonica germplasms having wide compatible gene with indica TGMS lines for exploitation of intersubspecific heterosis.

Analysis of combining ability of two-types of male sterile and four restorer lines of Zinnia elegans

“…For example, in sorghum Reddy et al (2007) reported heterosis to reduce the number of days to flowering, while increasing the subsequent grain yield. Heterosis-related increases of grain yield are extremely important for many crop plant species, including chickpea (Dhaliwal and Gill 1973;Hegde et al 2007), rice (Shukla and Pandey 2008;Young and Virmani 1990), sorghum (Reddy et al 2007;Kenga et al 2004) and wheat (Borghi and Perenzin 1994;Krystkowiak et al 2009;Li et al 1997). Conversely, heterosis is frequently associated with a reduction of a quantitative trait and this can also represent an advantage in breeding programmes (Reddy et al 2007;Maris 1989;Mebrahtu and Mohamed 2003).…”

“…The discovery of male sterile lines has enabled the pollination control system to be more efficient and economic. Currently in many plant species, the production of F 1 hybrid seed relies on the use of male sterility (He et al 2009;Kaya 2005;Kenga et al 2004;Laureti and Gatto 2001;Marciniak et al 2003;Reddy et al 2007;Shukla and Pandey 2008;Sindagi et al 1979;Tao et al 2004;Young and Virmani 1990). Knowledge of the effects of combining ability is useful in the selection of parental genotypes (i.e.…”

“…Breeders can utilize this information to select the best parents and determine which breeding strategies will be effective for the improvement of specific traits. There are numerous reports where combining ability analysis has been used to describe the breeding value of parental lines with respect to their potential to produce hybrids, and also to provide basic genetic information on the inheritance of a given character in plant breeding (Reddy et al 2007;Borghi and Perenzin 1994;Dhaliwal and Gill 1973;Hegde et al 2007;Kalloo et al 1974;Kenga et al 2004;Krystkowiak et al 2009;Romanus et al 2008;Li et al 1997;Maris 1989;Mastebroek et al 2002;Satija and Thukral 1985;Shukla and Pandey 2008;Sprague and Tatum 1942;Stuber 1994;Mebrahtu and Mohamed 2003;Young and Virmani 1990). Although hybridization using male sterile lines is common practice in commercial applications of Zinnia elegans, there has been no report on the importance of combining ability and hybrid breeding of male sterile lines in the species.…”

Agro-morphological and Molecular Characterization of Sorghum (Sorghum vulgare L.) for Water Stress Tolerance

“…Combining ability estimates serve as a useful guide during selection of parents for hybridization programs (Shukla and Pandey, 2008). The selection is based on the performance of hybrids and are related to the general (GCA) and specific (SCA) combining abilities of the inbred lines involved in the cross.…”

A new gene for hybrid sterility from a cross between Oryza sativa and O. glaberrima

“…2008) and indica × japonica (Sano 1990, Zeng et al. 2007, Shukla and Pandey 2008, Wang et al. 2009a,b).…”