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developed two varities of japonica suitable for tropics, which are NSIC Rc 170 or IRRI 142, ( now called MS 11) and NSCIC Rc 220 or IRRI 152 for large scale cultivation in the, Philippines. Japonicas respond well to intensive crop management due to short stature and, sturdy stem, narrow , errect and dark green leaves., •, , Javanicas are grown mainly in parts of Indonesia. They have fewer tillers ,tall stature with, sturdy stem, long panicles and long bold grains., , Botany of Paddy:, Rice is one of the most important food crops in the world and it is the staple food for over 2.7 billion people. In India, area, under rice is 44.6 m ha with total output of 80 million tonnes (paddy) with an average productivity of 1855 kg/ha. It is, grown in almost all the states. West Bengal, Uttar Pradesh, Madhya Pradesh, Bihar, Orissa, Andhra Pradesh, Assam,, Tamilnadu, Kerala, Punjab, Maharashtra and Karnataka are major rice growing states and contribute to total 92% of area, and production., , Root:, Rice form a fibrous root system consisting of seminal, nodal and lateral roots., , Clum or Stem:, The culm, or jointed stem of the rice, is made up of a series of nodes and internodes, The stem of rice popularly known as the haulm or the culm, is generally erect, cylindrical, hollow at the, internodes and solid at the nodes.
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Tillers:, Early tillers arise from the main culm in an alternate pattern., Primary tillers originate from the lowermost nodes and give rise to secondary tillers., Secondary tillers produce tertiary tillers., Each tiller is an independent plant., , Leaf:, The node or nodal region of the culm will bear a leaf., Leaves are borne alternately on the culm in opposite directions. One leaf is produced at each node., The topmost leaf below the panicle is the flag leaf. The flag leaf contributes largely to the filling of grains, because it supplies photosynthetic products, mainly to the panicle
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Panicle:, , The terminal component of the rice tiller is an inflorescence called as panicle. The inflorescence or, panicle is borne on the uppermost internode of the culm. The panicle bears rice spikelets, which, develop into grains., , The panicles bear spikelets, most of which develop into grains. These spikelets are borne on, the primary and secondary branches. The spikelet is the basic unit of the inflorescence and panicle. It, consists of the pedicel and the floret, Spikelets:, The spikelets are carried on small rachillae at the ends of the branches of the panicle., The spikelet in rice is single flowered enclosed by the lemma and palea., There are six stamens, in two whorls of three each, the filaments being very slender and delicate and, having sudden exertion of growth at the time of anthesis.
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What is a hybrid?, A hybrid is the first generation offspring of a cross between two genetically diverse, parents., , How to obtain hybrid rice?, Hybrid rice is produced when the egg is fertilized by pollen from anthers of a rice plant from, a different variety or line., In order to produce great quantities of hybrid seeds, two kinds of parental lines are needed,, a seed parent which is usually male sterile and a pollen parent.
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Why are we interested in hybrid rice?, , Hybrids show a 15-20% of yield advantage giving higher economic returns., Hybrid vigor or Heterosis is a universal phenomenon in which the F1 shows superiority to, both parents in agronomic traits or yield., It is present in all biological systems and has been exploited commercially in many, agricultural crops.
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Male Sterility Systems in Rice, Male sterility is a condition in which the pollen grain is unviable or cannot germinate and, fertilize normally to set seeds., Male Sterility Systems (genetic and non-genetic):, • Cytoplasmic genetic male sterility (CMS), Male sterility is controlled by the interaction of genetic factors (S) present in the, cytoplasm and the nucleus (s)., • Environment-sensitive genic male sterility (EGMS), Male sterility system is controlled by nuclear gene expression, which is influenced by, environmental factors such as temperature (TGMS), day length (PGMS), or both, (TPGMS)., • Chemically induced male sterility, Male sterility is induced by some chemicals (gametocides), , Brief history of hybrid rice:, 1926 - Heterosis in rice reported, 1964 - China started hybrid rice research, 1970 - China discovered a commercially usable genetic tool for hybrid rice (male sterility in a, wild rice = Wild Abortive ), 1973 - PTGMS rice was found in China, 1974 - First commercial three-line rice hybrid released in China, 1976 - Large scale hybrid rice commercialization began in China, 1979 - IRRI revived research on hybrid rice, 1981 - PTGMS rice genetics and application was confirmed, 1982 - Yield superiority of rice hybrids in the tropics confirmed (IRRI), 1990s - India and Vietnam started hybrid rice programs with IRRI, 1991 - More than 50% of China�s riceland planted to hybrids, 1994 - First commercial two-line rice hybrid released in China, 1994 - 1998 - Commercial rice hybrids released in India, Philippines Vietnam
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Morphological Model of Super High-yielding Hybrid Rice:, , , Plant height = 100 cm, with culm length = 70 cm, Uppermost three leaves:, Flag leaf, long, 50 cm, higher than the panicle top 20 cm. The 2nd leaf from, the top: 10% longer than the flag leaf, and over the top of the panicle. The 3rd, leaf = the middle position of the panicle, Erect: the leaf angles of the flag, 2nd and 3rd leaves are around 5, 10, 20, degrees, till mature., Narrow, V-shape and thick: narrow with 2 cm when flattened., Plant type: moderate compact with moderate tillering capacity; drooping panicles, after filled, above ground - 60 cm, erect-leaved canopy without appearance of the, panicles, Panicle weight and number: grain weight per panicle = 5 g, 2.7 million panicles per, hectare., Leaf area index (LAI) and ratio of leaf area to grains: the LAI is ~ 6.5 based on the, uppermost three leaves, the ratio of leaf area to grain weight is 100 : 2.2-2.3,, meaning that to produce 2.2-2.3 grams of rice, 100 cm2 of the upper three functional, leaves are needed., Harvest index > 0.55, , By: Dr A. C. Singh,, HOD, Agronomy
