Evaluation of perennial rice BRRIdhan91for superior ratooning and development of one line hybrid to fix heterosis in rice.

One line hybrid rice (as a clone of mother plant) with perennial growth and superior ratooning ability might be an innovation over three and two-line hybrid which eliminates complexities of seed production. Development of BRRI dhan91 having perennial growth opens the door of breeding for better ratooning. Therefore, objectives were to evaluate ratooning abitity (up to 5th and 6th ratoon crops) under standard ratoon system (10 cm stubbles) using perennial BRRI dhan91, non-perennial (BRH11-9-11-4-5B, BR9392-6-2-2B) and their two hybrids. Studies showed that main and ratoon crop of BRRI dhan91 has robust, tall (195 cm), erect, green plant with thicker and alive stem base at maturity. Stem of BRRI dhan91 contains three times more starch than BRH11-9-11-4-5B. Main crop didn't die after harvest, new tillers originated from dormant buds of stubbles under soil surface. Those buds/seedlings provided a second crop (up to 5th and 6th crops) as taller as main crop- yield and growth duration was same as main crop. Attempts to discover apomixes haven't succeeded. However, superior ratooning of two hybrids could be an alternative of apomixes or fixing heterosis of one line hybrid, as propagated without seeds. Hydrid-1 showed higher positive heterosis for superior ratooning (21%), dry matter (35%) and yield (25%) over better parent. Selection of hybrid-1 might lead to improvement of perennial ratoon growth having better dry matter (11.4 t/ha) and yield (10.1 t/ha). Further, comparison of ratoon crop of F1(BRRI dhan91/ BRH11-9-11-4-5B) with its main F1 seed crop demonstrated that ratoon hybrid-1(up to 5th and 6th ratoon crops) had almost equal expression of perennial growth, plant height, dry matter and yield as like its main F1 crop. These result indicated that fixation of heterosis occur for perennial growth, dry matter (11.9 t/ha) and yield (11.2 t/ha) in main and ratoon crop of hybrid-1. The aforementioned performance had successfully been transferred almost same level through ratooning up to 6th ratoon crops. This is the first invention in sustainable hybrid crop cultivation without seeds up to 6th ratoon season - could provide a hope of sustaining food security in Asia.