On Rice Diversity: Bangladesh Perspective | 2018-01-20 | daily-sun.com

On Rice Diversity: Bangladesh Perspective

Jiban Krishna Biswas PhD

    20 January, 2018 12:00 AM printer

On Rice Diversity: 
Bangladesh Perspective

Jiban Krishna Biswas PhD

Rice (Oryza sativa L) appears to be the only prime crop that has the unique adaptation ability under any environment. The species made its way from the lost continent Gondwana Land to the East up to Japan and to the West up to Africa. Now it is a crop grown almost all over the world. It is grown well over the tropical to the sub-tropical belt of either side of the equinox.

Rice is mostly grown as a lowland crop but pretty adaptable to the upland conditions also. The crop also grows quite well from the saline coastal belt of the Ganges delta to the arid valley of the Nile.  It can also be grown even in the chilly weather up in the Kashmir region of the Himalaya or Hokkaido in Japan. This is the only crop adaptable to an ecotype where the flood water depth goes its extreme up to four meters.

Therefore the species rice had to experience an exclusive diversity of evolutionary paths.  The diversity of rice is mostly concentrated in Asia. Vis-à-vis Africa experienced the same but not as many as in Asia with a sister species Oryza glaberrima Steud. These are the cultivated species of the genus Oryza. Beside these two cultivated species, rice has 20 wild relatives also distributed over the tropical and temperate regions of the world. It is claimed that more or less 140,000 varieties of rice were cultivated prior to the introduction of HYVs though many of them have eroded already.  Fortunately, most of them are in the human captivity not in the field but in the artificial gene bank. The International Rice Research Institute (IRRI) has a collection of 120,000 varieties. An initiative was active in the early 1960s to preserve crop genetic resources. The Consultative Group for International Agricultural Research (CGIAR) came forward to play a significant role in cooperation with the national agricultural research institutes. Accordingly, IRRI was in the process to establish one of the richest gene banks on rice with the assistance of the national institutes. BRRI (Bangladesh Rice Research Institute) was in the priority list. IRRI has the similar understandings with the other national institutes also and arranged three international workshops on the importance of germplasm collection in 1977, 1983, and 1990. Then in 1993, the Swedish Development Corporation came up with the IRRI to assist its conservation activities. 

As per the South Asian perspective the then Bengal was very rich in rice diversity. It is said that some 30,000 varieties were cultivated in the past. This was a rough estimation made by a British bureaucrat who extensively travelled across the country during his tenure. GP Hector, a rice scientist from Imperial Agricultural Research Institute, Tejgaon farm, Dhaka, conducted another survey some 80 years back from now (2018). As per his estimate farmers were used to cultivate 18,000 rice varieties all over the undivided Bengal during that time. There was no record of genetic erosion in those days. So, the huge difference between the two surveys might be due to the methodological error adopted in their studies. Even a survey in early 1982 at BRRI recorded 12,487 varieties of rice in Bangladesh. They are recorded in the form of popular name told by the farmers during the survey. A recent survey recorded some 1,000 varieties of special significance in some pocket areas of the country which are still taken care of by some farmers.  It means that the country has already experienced a serious jolt of genetic erosion of rice and the remaining are in the risk of extinction within a few years.

However, BRRI has a collection of around 8,000 varieties in its gene bank. Out of these, around 6,000 thousand are from the landrace origin. Having not seen in the fields the environmentalists and conservationists are always in a cry that all the landrace varieties have eroded already. Yes! Many of the varieties have eroded from the field. But still a significant number of varieties are preserved in the gene bank. Can we blame the farmers, scientists or policymakers for this genetic erosion?  Probably, we should not. In principle a human being anywhere in the world must not be kept unfed. That is the priority task for a society. So there was no way but to replace the traditional varieties with the HYV ones in the recent past. But the scientists were aware of the importance of the landrace varieties.

So with the introduction of HYVs, they have initiated a unique job to collect and preserve the varieties in the process of extinction as I have mentioned already. They are the ones who realised the importance of the landrace genotype prior to the environmentalists. That is the reason why we have an established rice gene bank now. Now a question… Can a variety preserved in the gene bank (ex-situ) able to carry out the essence of the tradition of rice varieties the same way the land race varieties which are still in the farmers’ field? 

I will be discussing the matter later.

Prior to that let me have a brief account on how the rice varieties are preserved in the gene bank. Generally, there are two methods to preserve the crop varieties. The first one is ex-situ, i.e. in an artificial environment (gene bank) and the other is in-situ—-the conventional procedure where farmers used to grow the varieties every year.  In the gene bank (in situ method) internal moisture of the viable seeds are brought down to 4% gradually to preserve in a certain low temperature. Thus the seeds could preserve their viability from five years to fifty years depending on the temperature and the associated environment of a gene bank. There are two types of management systems that are maintained generally to preserve the seeds. The seeds of a variety could maintain their viability for 10 years if they are stored in 4 ºC and for 50 years if they are stored in minus 20 ºC.

Bangladesh has a tradition of rice germplasm preservation since 1911, the year research initiated on rice formally.  Scientists had to collect germplasm across the country. The suitable varieties were selected from the collected germplasm through the pure line selection methods. But they did not have well-equipped germplasm centre as we have now. So they have to grow all the collected materials in the field every year, same as that of the in-situ conservation method. Only the difference is, in the in-situ conservation method varieties are grown in the location of origin by the farmers themselves. In the Pakistan regime, scientists of the Dhaka farm continued their conventional conservation activities. However, in the 1960s, the then Pakistan Government made a plan to establish the second capital of Pakistan under the name of Ayub Nagar (present Sher-E-Bangla Nagar) just replacing the established agriculture research centre at Tejgaon, Dhaka. The scientists were asked to shift all the research establishments from the proposed Ayub Nagar area. No alternative arrangements were made for the relocation of the research establishments. The scientists even did not know where to go. They could just manage some spaces of Livestock farm at Savar to continue some of their emergency works.

During their shifting, scientists lost more than 400 rice germplasm. That was a huge loss at that time. But the then government did not care about that. Anyway, following the tradition, since its establishment, BRRI started the same activity with a new format. That is the initiative of a small gene bank in its own way. That modest initiative has turned to one of the richest germplasm of rice for a country like Bangladesh. But this kind of ex-situ preservation system (gene bank) has aroused an important issue. 

Some of the scientists claim that the varieties stored in the gene bank for a long time are expected to miss the opportunity of an evolutionary process that creates germplasm. This question is not only limited to rice but for the other crops also. It is also questionable how much a variety could adapt in the changing climatic conditions after getting up a long-dormant condition. The situation might be worse for 50 years storage than 10 years.

Therefore to overcome those problems it is better to adopt the in-situ conservation system. The scientists, extension experts and farmers together might play significant a role in this respect. The policymakers should understand the logic behind it. As I have mentioned earlier that there are some varieties of special significance still available in the field. There should be a programme to work with the farmers who are still cultivating those varieties so that they could spare a patch of land at the corner of their main farm for the sake of the in-situ conservation. Another programme may be considered. The prospective location specific varieties searching from the list of gene bank could be re-released to the farmers for their cultivation again. Thus, a diversified case of rice could be maintained to some extent in the field. Prior to that, we must have to realise ourselves that achieving sustainable food security would be easier if we could bring back some diversity in the case of our staple food crop rice.


The writer is the Director General (Former), Bangladesh Rice Research Institute, Gazipur