Induced Radicle Rooting : An alternative Technique for Rapid and Mass screening of Rice Genetic Accessions for Deep Root system

Abstract

Drought is a recurrent phenomenon in the fragile crop production environments. Drought resistant crop varieties strike roots deeper into the soil to withstand drought spells during the crop growth period better than the shallow rooted varieties. Thus the deeper they strike roots under stress, the better their survival. Plant breeding for less than ideal condition is very difficult especially for breeding resistance to drought. The existing screening techniques are based on lateral root or fibrous root development for monocots like rice or barley .This paper explains a new innovative approach called Induced Radicle Rooting (IRR) technique which is a novel technique in which radicle root is allowed to grow by suppressing the growth of the lateral roots. The induction of radicle rooting is achieved in three steps viz.(i) by allowing to touch the radicle of the germinated seed on the water level keeping other parts above. (ii) by reducing the water level of the well periodically then and there when the radicle starts growing (iii) by allowing the growth of the radicle down deeper in the capillary tube in such a way by arresting crown and lateral roots. As the moisture stress is artificially simulated right from the beginning in the capillary tubes, the varieties tend to put forth roots as deep as the water level is. The varietal difference in the radicle root length is so sharp that the shallow rooted varieties are differentiated from the deep rooted ones remarkably. It is a non destructive method and significantly correlated to field data ( r = 0.951). This technique a first of its kind shall be useful as a valuable tool to the scientific community engaged in searching for deep roots.