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Deciding factors of Yield Disparity in Rice




Former Directors, Rice Research and Development Institute

We have observed earlier, in media discussions, that the majority of resource personnel were critical about modern rice varieties in Sri Lanka. The issues brought up against were Genetic Modification, Glycemic Index, Protein Status, Cooking and Eating Quality, Nutritional and Medicinal Properties, to mention a few. There appears to be a knowledge gap, as the critics were non-agricultural professionals; some of them were incapable of even sorting out weedy rice from real ones.

Recently, (Vidusara, Page 10, Oct 28, 2020), a scientist highlighted many traditional varieties of superior quality rice, but without citation of any scientific or experimental evidence for his claims. Among them was Kuruluthuda, a traditional rice variety, highlighted for its aphrodisiac qualities, availability of essential fatty acids, proteins, vitamins and Magnesium with no quantifications, and also its ability to regulate blood cholesterol. This is fantastic, but this variety needs some clarification at this point. Kuruluthuda reported here was red pericarped, 3.5 month variety. If so, it can be cultivated in both Yala and Maha seasons. The variety identified as Kuruluthuda in the list of pureline selections of the Department of Agriculture (Rhind,1948) was white pericarped, 5 to 6 month photosensitive and can be grown only in Maha season. Prof. M. F. Chandraratne too reported photosensitivity of Kuruluthuda in his text book on Rice Breeding. If so, are we referring in both these instances to the same variety or two different varieties?

And now, there is a new trend in criticism of local rice research, for not delivering rice yields in par with countries like Australia, Japan, China, etc.. In this instance, undisclosed technological gaps are highlighted for yield disparity. We, as rice scientists in the country, are left in the dark under these circumstances, as it appears the critics are overstepping their professional boundaries to invade the rice sector.

In China, the majority of rice cultivars are hybrids exploiting F1 hybrid vigor. Hybrid rice is a few steps ahead of us, as we continue research on developing local parental varieties for hybrids, and cross pollination for the F1 seed production procedure. The other countries, Japan, Australia, etc., grow conventionally developed varieties of their own, as in Sri Lanka. However, the disclosure in the text below is to keep critics aware of the biological limits of the tropical environment for any quantum jumps in rice yields, through biotechnological approaches or otherwise.

It is scientifically accepted that the performance of any crop species (genotype) results from its interaction with the environment it is exposed to. Rice is no exception to this phenomenon. The crop environment is composed of biotic (pests and diseases) and abiotic (soil and climate) components. These are basic facts that one should be familiar with, before being critical of paddy cultivation in Sri Lanka.

Sri Lanka is located within the tropical belt of the northern hemisphere, between latitudes 5º55′ and 9º49′. The countries being compared, Australia, Japan, China, etc., are in the temperate zone, and are blessed with soil and climatic factors conducive for rice cultivation.

Irrespective of the parent material involved in the genesis, the soils in Sri Lanka are leached by heavy monsoon rains, and therefore less fertile; particularly the rice soils are subjected to intensive and continuous double cropping, without a resting or fallow period for replenishment. Also, the consistent soil microbial activity, caused by high temperature regimes in the tropical belt, decomposes the organic content rapidly, affecting physical, chemical and biological properties of soil, especially the Cation Exchange Capacity (CEC). As a result, the rice farmer in tropics, Sri Lanka in particular, will have to use both organic and inorganic manure regularly, to sustain good CEC and soil fertility for high productivity.

Soils in the temperate zone are fertile, rich in organic content and CEC due to slow microbial activity resulting from low temperature regimes. In addition, the Japanese paddy fields are provided with subsoil drainage facilities to improve soil productivity. The Australian rice soils are rich in native fertility, and sometimes application of nutrients P and K is not needed for rice production; also the adoption of strict plant quarantine measures keeps the country free of many rice pests and diseases. The pest and disease cycles are usually interrupted in the winter, due to low temperature and/or unavailability of alternate host plants. These ground situations cannot be ignored in a fair comparison of rice productivity in the two different regions.

The other major factor determining crop productivity in the two zones is the difference in photoperiod which involves photosynthesis; i.e. the net-assimilation rate after allowing respiratory losses. In modern rice varieties, the plant canopy structure is designed to improve photosynthetic efficiency, while containing respiratory losses.

We experience short and long day photoperiods regularly within each year (except on the equator) depending on the latitude concerned. The longest day (June 21) in the Northern hemisphere is the shortest day in the Southern, and the shortest day in the Northern (December, 21) is the longest day in the Southern hemisphere. These are basic, but important facts, ignored in the comparison of potential yields among different regions.

The so-called high potential countries do cultivate only one rice crop a year, and the cropping season is determined when the temperature is conducive and the photoperiod is almost above 13 hr/day. Photoperiod reaches its peak (around 16 hr/day) when the crop is in its reproductive phase; the crop too spends more than four months in the field to mature. In contrast, the poor farmers in Sri Lanka have to cultivate their major rice crop (Maha) when the photoperiod is below 12 hr/day throughout the season (October – February); and their minor crop (Yala ) when the photoperiod is just above 12 hr/day, but never exceeding the maximum of 12 hr and 30 min.. The crop duration in either case is less than four months. Sri Lankan rice crop eternally suffers this disadvantage of photoperiod difference between the temperate and tropical zones. Also, a single day increase of crop

duration, within the range of 3.5 – 4.5 months of age, leads to a yield increment of around 0.05 t/ha, even under local climatic conditions.

The facts above (soil fertility, photoperiod and crop duration) explain the yield disparity between Sri Lanka and countries away from the tropical belt. Any critic can evaluate popular Japonicas, Koshi-hikari, Akitakomachi, Reiho etc. or the Australian counterpart; Calrose, Ingra, Blue-bonette, Bluebelle etc. or any other known high potential technology package under the local agro- ecological conditions, and verify how they perform. The results will convince you that it is not the cultivar or technology but the crop environment (Soil and Climate) that is the deciding factor of yield disparity between the two regions; and that your conclusions, potential of variety and/or technological gap, are utterly irrelevant, invalid.

A fair comparison is needed among the countries within the tropical belt, without confounding the effects of soil and climate of other regions, to conclude the claims of low yields in Sri Lanka by these uninvited critics. Also, there is no known single gene solution in biotechnology (genetic transformation), similar to that of Bt or

β Carotene (golden rice) gene, leading to a quantum jump in yield potential; rice yield, as in any other crop, is determined by quantitative trait loci (QTLs).

Also, it is important to record that the national average rice yield (year 2020) was 4.85 t/ha. In some stable crop environments, yields of 10 t/ha, approximating the potential of the cultivars, is not uncommon despite overall average performance is low. The inconsistent yield by any genotype within the country is attributed to the effect of specific agro-ecological environments.

Scientists have made futile attempts to change the photosynthetic system of rice, C3 to more efficient C4, with different approaches. There had been reports of rice-sorghum hybridization, with the objective of changing rice to C4 photosynthetic system, by introducing Kranz anatomy with bundle sheath cells carrying chloroplasts. Also, there were some unsuccessful atmospheric N-fixation projects (Azolla-anabaena complex, blue green algae and other soil microbes and Susbania spp.) where the cost factor has overridden the cost of inorganic N. There was also the internationally known SRI (System of Rice Intensification) project in Sri Lanka implemented around two decades ago, but no participant farmers of the project are traceable now. There are many more examples of this nature. These are the realities we have faced already with innovative technologies in rice. We know what is appropriate and what is not. Let the rice researchers work peacefully towards their intended objectives, without being disturbed.

Sri Lankan rice scientists have gained a lot from little more than a century’s old, recorded history of local rice research and field experiences; they understand the farmer’s need very well and appropriateness of technologies they could adopt. It is natural, with the experience behind, that the researchers may disagree with inappropriate, expensive, futile technological innovations. The country had bitter experiences in the past by embarking on projects designed by experts with no local experience, but had spent their youth in green pastures abroad (e.g. Psophocarpus tetragonolobus (Dambala) project).

The Department of Agriculture has competence and capability to decide on seasons (Yala, Maha) and agroecological regions, based on long-term changes in soil and climatic parameters, and they will attend to any changes as and when needed. NamingYala and Maha seasons may be older than 900 years, but as long as no consistent and significant differences are noticed, the cropping seasons can remain as designated. The major climatic regions and agro-ecological zones were mapped by scientists of high caliber in the past, and their successors are consistently monitoring the changes in respective parameters for necessary amendments.

Many things have happened in the rice sector since the green revolution in the 1960s. We really feel sorry for the poor knowledge of some critics in the field of local rice improvement program, and the ignorance of the fact that the Department of Agriculture initiated and continued to release modern rice varieties in Sri lanka since 1970, with Bg 11-11 as the first improved cultivar. The process is still being continued.

The local rice scientists contributed their best within the available facilities and the limited budgets, and are satisfied with their accomplishments, as the rice production within the country can look after the national requirement.

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An air of discontent prevails



We have had a series of “Avurudhu parties” here in Aotearoa. No shortage of Kavum, Kokis, Athiraha, and even Wali Thalapa. Buffalo curd available locally and of course imported treacle in abundance. Yours truly has assumed the role of a fly on the wall during these festivities and gleaned much information, worth talking about.

First to get on to the Pearl, the talk of the botched-up vaccination plan and running out of the second dose of vaccine. Bizarre permutations as to what would happen if the second dose was not available on time and to who would be press-ganged into getting the “dodgier” types of vaccine from China and Russia, etc. The possible repercussions of getting a second dose of another type of vaccine to the original, the speculations of which left me rather glad that the general populace of Aotearoa has not been vaccinated to date. The talk moved on to the Easter bombings and the recent comments by leaders of the Roman Catholic church as to the possible perpetrators of the attack. Some increasingly obvious conclusions as to those responsible for the planning and funding of same are being reached by those other than some of us who dared to voice our opinions over a year ago! This combined with the increasing and very rapid unpopularity of the person they elected to high office hoping he was genie of the magic lamp type, and the possible reverse of Hong Kong that could take shape on the reclaimed land near the Colombo port, does not bode well for an already dubious future. By reverse of Hong Kong, I mean Hong Kong is trying to hold out as a bastion for democracy, whilst the proposed port city seems to be modeled on the opposite!

Moving on to Aotearoa, the rest of the world seems to be praying for a leader such as our own Jacinda Ardern, but the fat cats of Aotearoa are getting rather sick of her. Those who own multiple houses and have been setting off their interest payments against their taxes due to a loophole in the law that has now been plugged are grumbling. The fact that most young people can’t afford to buy their first houses due to rich people and property developers snapping up all available property, happily funded by banks who are only interested in the bottom line, is of no consequence to them. The fact that this could lead to so much discontent that it could even lead to armed insurrection doesn’t bother them. They seem to have forgotten that we have had almost no deaths and hardly any Covid 19 cases in our community when they say that the lockdowns, we underwent were too excessive and how the economy and business sector has suffered. These very people throng the stadia during the rugby and cricket games and enjoy music concerts with gay abandon. Megacorporations are not happy about the restrictions that are coming on with regard to the use of Liquid Petroleum Gas (LPG) due to environmental concerns. To top it all off I had a lecture from my 13-year-old daughter about how I am being “led by the nose” by Jacinda Ardern and her propaganda! Where she got that from could only be from her elder brothers whose get rich quick schemes have seen a setback due to certain leftist policies coming in from the Labour government that is in power with an absolute majority.

I laugh to myself and think about other examples I have seen of self-proclaimed pundits never being content with their lot. My education was in a very large Government school. As a perfect and a member of some sports teams we handled the administration and some of the governance of this school. Later in life when my children were attending a private school I got involved in the Executive committee of the PTA of that school. The “problems” faced by the private school and the vast dramas that were involved in trying to solve those problems were laughable when compared to those faced by even us, senior students (a much lower level in the administration) of the Government school.

It led me to believe that people always grumble. They are never content with their lot and there is always someone plugging their case and trying to sow the seeds of discontent among the populace. If those living in Aotearoa, in the present situation and well aware of the chaos and mayhem that is prevailing in the rest of the world are dissatisfied, when will anyone be satisfied? Everything is relative and one should try to step outside the confines of one’s own situation and look at the broad picture. In the words of learned barristers, I rest my case!

This week’s missive will not be complete without a tribute to the memory of Prince Phillip, the Duke of Edinburgh. He lived through some of the best and worst times of human existence on this planet and conducted himself impeccably. He showed his humanity and his failings, with a few bloopers down the line but most of those had an undercurrent of humor and couldn’t really be construed as offensive, despite the best efforts of the media and others to make them so. He served as consort to her Majesty the Queen with loyalty and aplomb and he leaves behind an enviable legacy in the world of conservation and youth affairs. It is hoped that his heirs will be up to the task for they face a task which in cricketing terms could be classed as coming into bat after the great Sir Vivian Richards had just scored a century, in his prime. Something very difficult to surpass in skill and entertainment value. Unfortunately, the Duke made just 99. May he rest in peace!


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We have much to learn; and emulation is no disgrace



“Imitation is the sincerest form of flattery that mediocrity can pay to greatness.” said Oscar Wilde who, through sharply ironic wit, often proclaimed the absolute truth.

Cassandra quotes him today as she wants to point out how much we in Sri Lanka can benefit by reaping some ideas from the recent royal funeral in Windsor. And she does not excuse herself for placing stress on our mediocrity as juxtaposed with greatness. Nationalists may shout themselves hoarse and bring down a few more majestic trees by decrying the comparison. They can justifiably claim we have a cultural heritage of two and a half millennia but have we remained cultured, following faithfully and correctly the four great religions of the world? A loud NO from Cass, echoed by millions of others. Though Britain’s development of the English language, culture, arts and science was later than our civilization, they outstripped all countries at one time and are again elevated, while we are poised on bankruptcy, with the begging bowl in hand and thugs and thieves as legislators. We in Sri Lanka are mediocre if not degraded against the greatness shown by the Brits in many spheres. This is no Anglophile speaking but a dame who was born when the Brits were leaving us to govern ourselves and grew up with our statesmen doing a jolly good job of it; Sinhalese, Tamil, Burgher, and a few Muslims taking the lead graciously and effectively with complete honesty, to serve the people. They maintained and improved our country so it was admired by others and even some desiring to imitate Ceylon as Singapore’s Lee Kwan Yew admitted. And where are we now? Except the Rajapaksa family from Medamulana, wearing rose tinted glasses or with eyes shut by arrogance, and their followers and throngs of sycophants, others see our country and our people for what it, and the people, really are. No need to elaborate.


The funeral of Prince Philip juxtaposed against customs here

The low-key funeral observing all Covid-19 restrictions was noteworthy for being utterly devoid of bombast and vainglory. It was dignified and moving. Cass wonders how many of her readers watched the funeral on Saturday 17, late evening here. Prince Philip had detailed all arrangements from the Navy being prominent and other Forces joining in plus the substitution of the gun carriage with a jeep he had helped design. The horse carriage he was adept at racing was stationed close by the entrance to the chapel. He has bequeathed it to the daughter of his youngest son and Sophie; the Wessexes having been very close to him and the Queen.

The entire proceedings proved first and foremost that the royal family observed strict pandemic restrictions like mask wearing and physical distancing. There was no one rule for them and another rule for us, thus proving beyond doubt that England (usually), and more so the Royal Family (definitely) are a country and an institution despising double standards. The monarch decreed and abided by the same regulations that have restricted everyone else in the UK, sharing their fate. An anecdote is relevant here. The Queen learned that lesson long ago. She was 14 when her mother said, after Buckingham Palace was bombed in September 1940, that she “could look the East End in the face now.”

Do all our people follow rules common to everyone? Oh! My heavens NO! There are differentiations according to layers in society. Shangri La would host a party for a hundred when only 30 are allowed to gather. During the height of the first wave when restrictions were strict, SLPP electioneering saw hordes thrust together and baby carrying, patting heads and hand clasping mostly by Mahinda Rajapaksha sans a mask. He has a charismatic bond with the masses but that needed to be curbed. Sajith Premadasa’s meetings were strict on physical distancing and mask wearing.

Only 30 were invited to the extremely solemn and yes, beautiful funeral service at Windsor Chapel. This meant eliminating even close relatives of the Family; but it was done. The Queen sat distanced from her daughter and sons and their spouses. Her now diminutive figure seated alone emphasized the loneliness she must be feeling after a close and successful marriage of 73 years.

This brings to mind our First Ladies. Cass steps out bravely to say that Elina Jayewardene was a gracious lady of restraint and dignity, the only perfect consort so far. Cass remembers Hema Premadasa beating her breast (true) and crying over the coffin of her late husband’s remains – in the true sense of the word – at the Prez’s funeral at Independence Square. There is dignity in restraint of even tears over a death in public. Among the women Heads of the country, the mother completely beat the daughter in dignity and ability.

We Sri Lankan women are now much more restrained in our mourning at funerals. Time was when widows even hoarsely wailed their sorrow, coiled and roiled with grief, and begged the dear departed “To look once more; say one word.” Cass in all the expressed grief of such funerals suppressed her laughter with difficulty. How would it be if the corpse obliged?

The choir at the funeral of Prince Philip was just four – one woman and three men. But their singing resounded in the high vaulted, completely majestic, centuries old church. The lone kilted piper within the Chapel evoked much. The service itself was short, just a Reading, prayers and listing of the multitude of honours bestowed on the Duke of Edinburgh, whose medals and decorations were on display beside the alter. The Archbishop of Canterbury, Justin Welby, and the Dean of Windsor, David Conner conducted the service.

To conclude, the Duke of Edinburgh had advised and laid stipulations on a simple funeral with the necessary pomp and pageantry but low key and very unostentatious. The actual funeral was even more low-key with mourners requested not to be on the streets or place flowers. The latter they did in all the residencies of the Royal Family in appreciation of a man who faithfully stood by the Queen and in his own way gave service to the nation.

Coming back to Free Sri Lanka, we seem to stress on that first word Cass inserted to the country name, even in these dire times of no crowds. And the worst is milling crowds are apparently encouraged to boost popularity of certain VVIPs by sycophants and by the preference/orders of the VVIP himself.

Consider the funeral of Minister Thondaman: crowds in Colombo and all VIPs wishing to register their presence before the body, and then the commotion at the actual cremation Up Country. Consider this year’s Sinhala New Year celebrations which were very dignified at the President’s residence but were inclusive of all traditions and a large gathering in the PM’s home, even raban playing by the Second Lady, and milling crowds outside.


Roller coaster ride of the country continues

Cass is relieved she had a topic to write on; namely that we should emulate the manner in which the much admired Duke of Edinburgh’s funeral was conducted, abiding by his stricture of it being low key and the country’s Covid restrictions. Our leaders especially must accept the saying I quoted at the beginning.

The country continues its roller coaster bumpy ride with some crying out the country is being sold to the Chinese, we will be a colony of theirs after they occupy the Port City; and others in remote areas sitting down for days on end, some near 100 days, drawing attention to the human elephant conflict. Much is touted about the Bill relating to the rules to govern the Port City.

Cassandra listens to all, and is somewhat warned and frightened, but cannot comment. However, one matter she speaks about loud and clear. The people must be told the status quo of the pandemic – daily numbers catching the infection and numbers dying. This is not for interest sake or ghoulish appetites; but to know how things are so we relax a wee bit or shut in more stringently. The Covid-19 Task Force, or the Health High Ups (not Pavithra please) should tell the country of the true situ of the pandemic as it holds the country in its grip. We want to know whether the grip is tightening or weakening. Please give us daily statistics. This newspaper announces total numbers. No help. Are we expected to jot down figures, subtract, and give ourselves daily infection and death statistics? No! It goes to prove that other matters – political slanted, ego boosting and economics – are more important than warning, containing the pandemic, and saving lives.

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Do you pump Octane 95 Petrol to your car to get better performance?



If your answer is YES, this article is for you

Dr. Saliya Jayasekara.

Senior Lecturer Department of Mechanical Engineering
University of Moratuwa

Many passenger vehicles, including three-wheelers and motorcycles are fueled by octane 95 gasoline when octane 92 gasoline (petrol) is available at a lower price. 

Otto engine (petrol engine) is an internal combustion spark ignition engine invented by a German engineer Nicolaus Otto in 1876 and used in most of the light weight vehicles including cars, three wheelers and motor bicycles. Otto engines can burn most of the hydrocarbon fuels (including hydrogen and ethanol) that can mix with air by evaporation (low boiling point). But the combustion characteristics of different hydrocarbons are not the same when burned inside an engine. If an Otto engine is designed for a particular fuel, it would not perform similarly with a fuel that has a different chemical composition.

In a well-tuned Otto engine run on gasoline for which the engine is designed, the combustion of the gasoline (petrol) / air mixture will continue smoothly from the spark plug to the piston head by igniting successive layers of the mixture as shown in Figure 1 (a).

If low grade gasolines are used, the combustion of some of the air/ fuel mixture in the cylinder does not result from propagation of the flame front initiated by the spark plug, but one or more pockets of air/fuel mixture explode (Detonate) outside the envelope of the normal combustion front as shown in Figure 1 (b). This detonation can cause severe damage to the piston and the head of the engine while deteriorating thermal performance of the engine (low efficiency)

Gasoline is a petroleum-derived product comprising a mixture of different hydrocarbons ranging from 4 to 12 carbon atoms in a carbon chain with the boiling point ranging of 30–225°C. It is predominantly a mixture of paraffins, naphthenes, aromatics and olefins. Additives and blending agents are added to improve the performance and stability of gasoline. The engine designers learned that straight-chain paraffin have a much higher tendency to detonate than do branched-chain paraffin.

The tendency of a particular gasoline to detonate is expressed by its octane number (ON). Arbitrarily, tri-methyl-pentane, C8H18 (iso-octane) is assigned an ON of 100, while the straight-chain paraffin n-heptane, C7H16 is given an ON of zero. Hence, a fuel sample with the same anti-detonation quality as that of a mixture containing 90% iso-octane and 10% n-heptane is said to have an ON of 90. Gasoline is made up of a mixture of mostly branched-chain paraffin with suitable additives to give an ON in the range 90 –100. It was also learned through experiments that the ON of a gasoline blends (e.g. gasoline and ethanol) can be calculated by using weighted average ON of each compound. Most importantly, the octane number has nothing to do with the heating value (Calorific value) or the purity of the fuel.

Engine thermodynamics show that engines with a high compression ratio offer higher thermal performance than engines with a low compression ratio. These engines having high compression ratio require high octane gasoline (for example octane 95) to avoid detonation. However, using gasoline having higher octane ratings for the engines designed for a low octane rating (for example, 92 octane) would not provide an additional benefit or loss, other than increased fuel cost.

Therefore, it is important to know the designed octane number of the engine before fueling (refer owner’s manual of the vehicle). For example: the minimum ON requirement for two and three wheelers in south Asia is 87 (The World Bank). Most of the Toyota, Honda and Nissan models including hybrid engines recommend 92 octane gasoline.

Dr. Saliya Jayasekara received the B. Sc. degree in mechanical engineering from university of Moratuwa in 2001, and the M.Sc. and PhD degrees in decentralized power generation systems from Royal institute of technology Sweden and the Melbourne University Australia in 2004 and 2013 respectively. He has well over 13 years of national and international experience in design and installation of centralised/decentralised power plants, boilers (utility/package) and heat exchangers. Currently he is serving as a senior lecture at University of Moratuwa, a visiting lecturer and fellow at Deakin University Australia.

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