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Rice Improvement during post IR-8 Period
Rice improvement research in India during the post IR8-Jaya period may be broadly discussed under five phases namely (a) the first decade of varietal breeding for different crop seasons and grain quality (b) the second decade of aggressive breeding for insulation of varieties with resistance against pests (c) the third decade of shift in breeding emphasis for adaptation to rainfed ecologies (d) the fourth decade of breeding aiming at breaching the yield level of semidwarf varieties through exploitation of hybrid vigour and new plant type varieties and (e) the current decade of breeding for finding new yield thresholds, enhanced input use efficiency, high nutritive quality and adaptation to changing climate using modern innovative genomic tools and techniques. While addressing such decade specific breeding priorities, no way the emphasis on other breeding objectives received less attention, given the overlap of breeding activities between successive decades and continued release of varieties for varied situations along with matching package of crop production practices. Varieties for varied crop seasons: The first generation semidwarf varieties fulfilled the requirement of a wide choice of early, medium early and medium duration types adapted to different crop seasons and cropping systems. About 40, 35 and 25% of over 1000 high yielding varieties evolved so far are respectively of medium, early and medium early maturity. Quick maturing varieties like Pusa 2-21, Anjali, Naveen, PRH-10, MTU 1010 etc. with high per day yield and potential to yield close to 80 – 90% of medium duration varieties greatly helped intensification and diversification of cropping by facilitating two rice crops in single cropped areas and three crops of rice or two crops of rice followed by a non-rice crop like short duration pulse or oilseed crop in double cropped areas, if water and climate are not limiting. As for grain quality, a major change could be brought about quite rapidly by evolving varieties with increasingly fine grain types in place of bold grain types. The fine grain type ranged from extra long slender to very short slender grains. Today, over 80% of non-basmati varieties are of fine grain types of acceptable cooking and eating qualities by combining ideal physico-chemical properties of starch. Among the fine grain rices, varieties like BPT 5204 (Samba Mahsuri), Sona Mahsuri, White Ponni etc. have become quite popular being traders’ and millers’ choice besides consumers preference. Breeding efforts to evolve high yielding basmati quality varieties, however, were not successful till mid 1990s, when Pusa Basmati 1 was released.