Vistas of national rice breeding and the myth of traditional riceOctober 20, 2014, 12:00 pm
By Dr Parakrama Waidyanatha
Continued from yesterday
Emergence of new rice varieties (NIVs)
Developing lodging resistant varieties then became the major challenge for the rice breeders, but fortunately, a new plant type created in Taiwan around 1960, exemplified by Taichung (Native 1) paved the way. It had short sturdy lodging resistant stems and short, upright, narrow leaves which could efficiently capture sunlight. The International Rice Research Institute based in the Philippines, experimenting with the new plant type developed the variety IR 8. However, both IR 8 and Taichung Native 1 failed to perform in Sri Lanka due to several reasons. Consequently, a major interdisciplinary rice improvement programme was launched with the objective of breeding short statured lodging resistant and fertilizer responsive varieties which were also resistant to diseases. Bacterial leaf blight (BLB) by then had turned out to be a major disease both here and elsewhere in Asia. A series of new improved varieties NIVs) such as Bg 11-11 (4.5 month variety) and Bg 34-6 (3.5 month variety) were released with the requisite attributes and a yield potential of 7 t/ha replacing H 4 and H 7. Another high yielding red rice Bg 3-5 replaced H 9. A major breakthrough was the development of Bg34-8 with a yield potential of 7 t/ha which became immensely popular, replacing the traditional variety Pachchaperumal with an average yield of only 2-3 t/ha. The new varieties had adequate resistance to BLB, and by 1974 the extent under them increased to over 55% as against the old improved varieties (OIVs, the H series) which were reduced to 24%. Over the years, more and more NIVs began to emerge, a major one being BG 94-1, a 3.5 month variety, which was able to replace even the existing 4 and 4.5 month varieties because of the higher yield potential and the ability to cultivate in both Maha and Yala seasons. The resulting conservation of water and field time was notable. The farmer acceptance of these NIVs continued to steadily increase replacing both the OIVs and the traditional varieties., and prompting breeders to steadily develop more and more dwarf statured varieties with increasingly higher yields. Some examples being Bg 90-2, Bg 94-1 and Bg 94-2 with yield potentials of 10 t/ha. The outstanding variety being Bg 94-1, a 3.5 month variety, which replaced Bg 43-1 as a variety for both seasons.
Although the NIVs had resistance to leaf diseases, they were found to be susceptible to several pests such as brown plant hopper and gall midge. However, our breeders were again able to breed varieties resistant to these pests with the introduction of resistant genes from some Indian varieties. Interestingly, two of the new varieties that emerged, Bg 400-1 and Bg 276-5 also showed resistance to iron toxicity, enabling their introduction to high iron soils in the Wet Zone. In fact they replaced the low yielding traditional varieties there from. So if the policy makers need varieties for iron toxic soils, the answer obviously is these new varieties and not the low-yielding traditional ones.
New red rice varieties with high nutritive value
Until about the late 1980s the rice breeding thrust had essentially been for productivity to achieve self sufficiency. The breeding scope thereafter broadened also to accommodate other attributes such as grain quality, nutritional value and consumer preference. All the NIVs bread hitherto were, however, white except Bg34-6 which was red but with limited yield potential. However, given the demand for red rice both from the northern and southern regions, a new high yielding variety of red rice, At 16 was developed for cultivation in the high potential areas. In the last two decades, NIVs exceeding 10t/ha such as Bg 358, Bg 352, Bg 300 and At362 which are now the most popular varieties among farmers emerged. Bg 403 is a red variety with the same potential yield. In addition many other red varieties in all age classes such as At 303, Bw 272-6/B ( 3month varieties), At 362, At353, Bw 364 (3.5 months) and At 402, Bw 401 and Bg 406 ( 4months) with yield potential in excess of 8 t/ha are available with equally high nutritive value as the traditional ones. Is there then any rationale to get back to traditional rice with inherently much lower yields and far greater susceptibility to pests, diseases and lodging. There are, however, claims of yields of 4 to 5 t/ha from traditional varieties apparently from small plots under well managed conditions. This may be true . But the danger is when extents under these varieties are expanded the risk for pest attacks increase substantially, and if they are to be grown organically without pesticide, the damage could be even greater.
The Department of Agriculture together with the Industrial Technology Institute (ITI) had in 2011 published a booklet comparing yields and nutritive values of 25 popular traditional varieties. Unfortunately only the nutritive values for some of the NIVs are in it but not the yields. Yield data records of NIVs from farmers fields are, therefore, incorporated for comparison. Anti-glycation data adapted from another publication by scientists of the ITI are also incorporated in the Table below. It shows that whereas the white varieties have lower protein, antiglycation ( higher the % , greater the health benefit) , antioxidant, iron and zinc levels, all red rice varieties irrespective of whether they are improved or traditional have comparable levels, and hence comparable health benefits.
The primary objective of grain breeding is to breed for energy (carbohydrate) and palatability, and other nutriments being secondary. They are usually derived from other foods - pulses, meat, fish, fruits and vegetables. Breeding high protein rice together with the high yield attribute had not met with much success although some traditional rice varieties with as much as 15% protein have been reported from other countries. About 8 – 9% protein appears what is achievable. In any case, given the massive yield advantage of all NIVs, there is no argument to return to traditional varieties on a large scale, given also the fact that the special attributes of these varieties are already available in the new red rice varieties.
Whither rice research?
The need is now not to go back to traditional rice, but to face the enormous challenges of climate change and the resultant vagaries of weather leading to crop losses, the demand for more food from the limited land resources given the ever increasing population, and more seriously, the problem of environmental pollution leading to diseases such as CKDU. Is our political resolve and resource allocation equal to the task? Sadly it is not so. We have, for example, an ageing rice research team in the Department of Agriculture without competent replacements for lack of a coherent training and succession plan. Of a full cadre of 8 -10 breeders and other rice researchers at the Rice Research and Development Institute , for example, there is now only one fully trained (PhD) researcher who is also due to retire in a few years. The situation is no better in other institutes of the Department of Agriculture (DOA). What are the authorities doing?
Last Updated Feb 27 2017 | 10:56 pm