Evaluation of promising TGMS lines for exploitation of two line heterosis in rice (Oryza sativa L.)

Abstract

Use of the thermo sensitive genie male sterility (TGMS) system in two line breeding is simple, inexpensive, efficient and eliminates the limitations associated with the cytoplasmic-geneic male sterility (CMS) system in rice. The present study is aimed to isolate and identify stable TGMS lines for commercial exploitation of two line heterosis breeding in rice. Two line hybrid in rice by employing thermo sensitive or photosensitive genic male sterility (TGMS or PGMS) lines is considered as an effective substitute for the three line hybrid using CMS system because of its potential to exploit higher heterosis and simple procedure of hybrid seed production [1]. Male sterility expression in TGMS lines is influenced by temperature. The temperature occurring just after panicle initiation is the most critical in the expression of sterility and fertility. TGMS lines are completely male sterile at higher temperature and almost normal male fertile at lower temperature. Therefore, the TGMS lines are used for purpose as male sterile lines for commercial hybrid seed production and as male fertile for self-multiplication at two different temperature. The TGMS system was considered to be more useful than the PGMS in tropical areas where large temperature differences between different regions and seasons exist [2]. In the tropical countries like India, where temperature fluctuations are common, the thermo sensitive genie male sterility (TGMS) system can be effectively utilized. Hence the present investigation was made to develop new TGMS lines with stable sterility, floral traits, medium duration group for exploiting two line heterosis in rice.