Vistas of national rice breeding and the myth of traditional rice



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A new improved variety showing short statured plants resistant to lodging and erect leaves
A traditional rice variety showing lodging which affects yield and milling quality of grain


By Dr Parakrama Waidyanatha


The media rhas ecently reported that the government is to embark on a major drive to promote production and consumption of traditional rice. Some 60, 000 ha (150,000 ac.) are to be cultivated this Maha season, that is, nearly 7.5% of the Maha rice extent. To date there is only less than 0.4% of this extent (3000 ha) under traditional rice. Is there adequate amounts of seeds of these varieties for cultivation of such a large extent? Equally importantly, will there be consumer demand for such large quantities given the fact that the price, on average, is double the common rice brands and many of the varieties are low palatibility. Some cursory enquiries from supermarkets indicated that the demand is low. However, some traditional rice varieties may be in demand for diabetic patients and the like because of the high anti-glycation property. There are, however, high yielding new red rice varieties with similar attributes (see Table below), and hence there is no justification to promote traditional varieties. Moreover, increase in the extent under traditional varieties should necessarily cause a concomitant decrease in the total national rice output as the traditional varieties yield on average about half that of newly improved varieties (NIVs). The negative repercussions are obvious.


To expand the extent under traditional rice is apparently a decision of the Presidential Taskforce on the Prevention of the Chronic Kidney Disease of Unknown Aetiology (CKDU) that is plaguing the Rajarata and some adjoining areas, killing 13 people, on average, a day and some 60, 000 people are said to be afflicted by it. Two of the recommendations of this Taskforce, apparently to combat the disease, as reported in the media, are promotion of "kola kanda" among children and consumption of traditional rice! It is also purported that this rice is to be grown organically without the application of chemical fertilizers and pesticides as they are implicated by some in the causation of CKDU. Acceptable scientific evidence for this implication, however, is yet to come. Be that as it may, can such large quantities of organic fertilizer be found in the cultivation areas? If they are to be transported from outside, what are the costs? Think before leaping! It is also argued that anaemia is on the rise in local populations, and traditional rice with higher levels of iron than in the modern varieties is an answer to it. The Ministry of Economic Affairs is said is to embark on re-cultivating abandoned paddy tracts in the Wet Zone, most of which had been left out because of low productivity and iron toxicity, with traditional varieties resistant to iron toxicity, and greater propensity for iron accumulation in the grain. Aren’t there new varieties with similar attributes and much higher yields? Are rice scientists of the Department of Agriculture consulted in these matters?


History of rice improvement


– a success story


The promoters of traditional rice should do well to glean a little into the history of rice breeding and selection and the potential of new improved varieties(NIVs) before retrogression into traditional rice! Rice breeding is an unprecedented success story in the annals of research in Sri Lanka on account of highly dedicated rice breeders and other rice scientists that has made the country self-sufficient in rice. Had we continued with traditional varieties we would not have produced today even a quarter of the national demand! Perhaps a PhD study (Niranjan, 2004) at the Postgraduate Institute of Agriculture, Sri Lanka tells it in a nutshell. This study on return on investment for the 40 year period, 1959 to 1999 on rice breeding and varietal selection reveals that a 1% increase in research investment increased national rice production by 0.37%. The benefit cost ratio and the internal rate of return were remarkable, being 2311 and 174% respectively. The average yield of traditional rice varieties in about 1900 was about 0.65 t/ha (13 bushels/ac) and over the ensuing 100 years, rice scientists have been able to increase it over 7 fold. In fact, there are now rice varieties with potential yields exceeding 11t/ha and the national average yield is now approaching 5t/ha.


In the early 20th century, the government gave priority to plantation crops to the neglect of rice research and development. However, in about 1920 initial pure line selection, that is selection of individual plants from populations of traditional varieties for grain yield and other desirable attributes, gave only a 15% increase in yield. The rice researchers soon realised that the quickest way of increasing yield was through application of chemical fertilizer. This was by then practised elsewhere, particularly in Europe. However, there was a problem in Sri Lanka. Most indigenous varieties were susceptible to lodging and diseases, especially the blast disease, and the susceptibility to both these conditions were aggravated by application of nitrogen fertilizer. Some resistant varieties, unfortunately, were not responsive to fertilizer. A pure line selection Murungakayan 302, a popular variety then, with resistance to leaf blast disease was also reasonably responsive to nitrogen fertilizer, but because of its excessive vegetative growth ,was susceptible to lodging. In general, therefore, these weaknesses of the traditional varieties, susceptibility to lodging and diseases and poor response to chemical fertilizer, necessitated breeding new varieties devoid of these weaknesses. Such varieties, namely, the H series emerged in the mid 1950s with the breeding efforts that commenced in the late 1940s. The H varieties were characterised by resistance to leaf blast and good response to applied chemical fertilizer. The H 4 variety , which later became very popular recorded the highest experimental yield of 7.1 t/ha as against the pure lines of traditional varieties of Murungakayan (M302) and Vellaiperumal (VP 2874) with maximum yields of 4.0 and 3.6 t/ha respectively. However, with heavy fertilizer use even H varieties were susceptible to lodging leading to crop losses and poor milling quality of grain.


Continued tomorrow


 
 
 
 
 
 
 
 
 
 
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