Connect with us


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.

Continue Reading
Click to comment

Leave a Reply

Your email address will not be published. Required fields are marked *


Strong on vocals



The group Mirage is very much alive, and kicking, as one would say!

Their lineup did undergo a few changes and now they have decided to present themselves as an all male group – operating without a female vocalist.

At the helm is Donald Pieries (drums and vocals), Trevin Joseph (percussion and vocals), Dilipa Deshan (bass and vocals), Toosha Rajarathna (keyboards and vocals), and Sudam Nanayakkara (lead guitar and vocals).

The plus factor, where the new lineup is concerned, is that all five members sing.

However, leader Donald did mention that if it’s a function, where a female vocalist is required, they would then feature a guest performer.

Mirage is a very experience outfit and they now do the Friday night scene at the Irish Pub, in Colombo, as well as private gigs.



Continue Reading


Dichotomy of an urban-suburban New Year



Ushered in by the ‘coo-ee’ of the Koel and the swaying of Erabadu bunches, the Sinhala and Tamil New Year will dawn in the wee hours of April 14. With houses to clean, preparation of sweetmeats and last-minute shopping, times are hectic…. and the streets congested.

It is believed that New Year traditions predated the advent of Buddhism in the 3rd century BC. But Buddhism resulted in a re-interpretation of the existing New Year activities in a Buddhist light. Hinduism has co-existed with Buddhism over millennia and no serious contradiction in New Year rituals are observed among Buddhists and Hindus.

The local New Year is a complex mix of Indigenous, Astrological, Hindu, and Buddhist traditions. Hindu literature provides the New Year with its mythological backdrop. The Prince of Peace called Indradeva is said to descend upon the earth to ensure peace and happiness, in a white carriage wearing on his head a white floral crown seven cubits high. He first plunges, into a sea of milk, breaking earth’s gravity.

The timing of the Sinhala New Year coincides with the New Year celebrations of many traditional calendars of South and Southeast Asia. Astrologically, the New Year begins when the sun moves from the House of Pisces (Meena Rashiya) to the House of Aries (Mesha Rashiya) in the celestial sphere.

The New Year marks the end of the harvest season and spring. Consequently, for farming communities, the traditional New Year doubles as a harvest as well. It also coincides with one of two instances when the sun is directly above Sri Lanka. The month of Bak, which coincides with April, according to the Gregorian calendar, represents prosperity. Astrologers decide the modern day rituals based on auspicious times, which coincides with the transit of the Sun between ‘House of Pisces’ and ‘House of Aries’.

Consequently, the ending of the old year, and the beginning of the new year occur several hours apart, during the time of transit. This period is considered Nonegathe, which roughly translates to ‘neutral period’ or a period in which there are no auspicious times. During the Nonegathe, traditionally, people are encouraged to engage themselves in meritorious and religious activities, refraining from material pursuits. This year the Nonegathe begin at 8.09 pm on Tuesday, April 13, and continues till 8.57 am on 14. New Year dawns at the halfway point of the transit, ushered in bythe sound of fire crackers, to the woe of many a dog and cat of the neighbourhood. Cracker related accidents are a common occurrence during new year celebrations. Environmental and safety concerns aside, lighting crackers remain an integral part of the celebrations throughout Sri Lanka.

This year the Sinhala and Tamil New Year dawns on Wednesday, April 14, at 2.33 am. But ‘spring cleaning’ starts days before the dawn of the new year. Before the new year the floor of houses are washed clean, polished, walls are lime-washed or painted, drapes are washed, dried and rehang. The well of the house is drained either manually or using an electric water pump and would not be used until such time the water is drawn for first transaction. Sweetmeats are prepared, often at homes, although commercialization of the new year has encouraged most urbanites to buy such food items. Shopping is a big part of the new year. Crowds throng to clothing retailers by the thousands. Relatives, specially the kids, are bought clothes as presents.

Bathing for the old year takes place before the dawn of the new year. This year this particular auspicious time falls on April 12, to bathe in the essence of wood apple leaves. Abiding by the relevant auspicious times the hearth and an oil lamp are lit and pot of milk is set to boil upon the hearth. Milk rice, the first meal of the year, is prepared separate. Entering into the first business transaction and partaking of the first meal are also observed according to the given auspicious times. This year, the auspicious time for preparing of meals, milk rice and sweets using mung beans, falls on Wednesday, April 14 at 6.17 am, and is to be carried out dressed in light green, while facing east. Commencement of work, transactions and consumption of the first meal falls on Wednesday, April 14 at 7.41 am, to be observed while wearing light green and facing east.

The first transaction was traditionally done with the well. The woman of the house would draw water from the well and in exchange drop a few pieces of charcoal, flowers, coins, salt and dried chillies into the well, in certain regions a handful of paddy or rice is also thrown in for good measure. But this ritual is also dying out as few urban homes have wells within their premises. This is not a mere ritual and was traditionally carried out with the purification properties of charcoal in mind. The first water is preferably collected into an airtight container, and kept till the dawn of the next new year. It is believed that if the water in the container does not go down it would be a prosperous year. The rituals vary slightly based on the region. However, the essence of the celebrations remains the same.

Anointing of oil is another major ritual of the New Year celebrations. It falls on Saturday, April 17 at 7.16 am, and is done wearing blue, facing south, with nuga leaves placed on the head and Karada leaves at the feet. Oil is to be applied mixed with extracts of Nuga leaves. The auspicious time for setting out for professional occupations falls on Monday, April 19 at 6.39 am, while dressed in white, by consuming a meal of milk rice mixed with ghee, while facing South.

Traditionally, women played Raban during this time, but such practices are slowly being weaned out by urbanization and commercialisation of the New Year. Neighbours are visited with platters of sweetmeats, bananas, Kevum (oil cake) and Kokis (a crispy sweetmeat) usually delivered by children. The dichotomy of the urban and village life is obvious here too, where in the suburbs and the village outdoor celebrations are preferred and the city opts for more private parties.



Continue Reading


New Year games: Integral part of New Year Celebrations



Food, games and rituals make a better part of New Year celebrations. One major perk of Avurudu is the festivals that are organised in each neighbourhood in its celebration. Observing all the rituals, like boiling milk, partaking of the first meal, anointing of oil, setting off to work, are, no doubt exciting, but much looked-forward-to is the local Avurudu Uthsawaya.

Avurudu Krida or New Year games are categorised as indoor and outdoor games. All indoor games are played on the floor and outdoor games played during the Avurudu Uthsava or New Year festival, with the whole neighbourhood taking part. Some of the indoor games are Pancha Dameema, Olinda Keliya and Cadju Dameema. Outdoor games include Kotta pora, Onchili pedeema, Raban geseema, Kana mutti bindeema, Placing the eye on the elephant, Coconut grating competition, Bun-eating competition, Lime-on-spoon race, Kamba adeema (Tug-o-War) and Lissana gaha nageema (climbing the greased pole). And what’s an Avurudhu Uthsava sans an Avurudu Kumari pageant, minus the usual drama that high profile beauty pageants of the day entail, of course.

A salient point of New Year games is that there are no age categories. Although there are games reserved for children such as blowing of balloons, races and soft drinks drinking contests, most other games are not age based.

Kotta pora aka pillow fights are not the kind the average teenagers fight out with their siblings, on plush beds. This is a serious game, wherein players have to balance themselves on a horizontal log in a seated position. With one hand tied behind their back and wielding the pillow with the other, players have to knock the opponent off balance. Whoever knocks the opponent off the log first, wins. The game is usually played over a muddy pit, so the loser goes home with a mud bath.

Climbing the greased pole is fun to watch, but cannot be fun to take part in. A flag is tied to the end of a timber pole-fixed to the ground and greased along the whole length. The objective of the players is to climb the pole, referred to as the ‘tree’, and bring down the flag. Retrieving the flag is never achieved on the first climb. It takes multiple climbers removing some of the grease at a time, so someone could finally retrieve the flag.

Who knew that scraping coconut could be made into an interesting game? During the Avurudu coconut scraping competition, women sit on coconut scraper stools and try to scrape a coconut as fast as possible. The one who finishes first wins. These maybe Avurudu games, but they are taken quite seriously. The grated coconut is inspected for clumps and those with ungrated clumps are disqualified.

Coconut palm weaving is another interesting contest that is exclusive to women. However men are by no means discouraged from entering such contests and, in fact, few men do. Participants are given equally measured coconut fronds and the one who finishes first wins.

Kana Mutti Bindima involves breaking one of many water filled clay pots hung overhead, using a long wooden beam. Placing the eye on the elephant is another game played while blindfolded. An elephant is drawn on a black or white board and the blindfolded person has to spot the eye of the elephant. Another competition involves feeding the partner yoghurt or curd while blindfolded.

The Banis-eating contest involves eating tea buns tied to a string. Contestants run to the buns with their hands tied behind their backs and have to eat buns hanging from a string, on their knees. The one who finishes his or her bun first, wins. Kamba adeema or Tug-o-War pits two teams against each other in a test of strength. Teams pull on opposite ends of a rope, with the goal being to bring the rope a certain distance in one direction against the force of the opposing team’s pull.

Participants of the lime-on-spoon race have to run a certain distance while balancing a lime on a spoon, with the handle in their mouths. The first person to cross the finish line without dropping the lime wins. The sack race and the three-legged race are equally fun to watch and to take part in. In the sack race, participants get into jute sacks and hop for the finish line. The first one over, wins. In the three-legged race one leg of each pair of participants are tied together and the duo must reach the finish line by synchronising their running, else they would trip over their own feet.

Pancha Dameema is an indoor game played in two groups, using five small shells, a coconut shell and a game board. Olinda is another indoor board game, normally played by two players. The board has nine holes, four beads each. The player who collects the most number of seeds win.

This is the verse sung while playing the game:

“Olinda thibenne koi koi dese,

Olinda thibenne bangali dese…

Genath hadanne koi koi dese,

Genath hadanne Sinhala dese…”

Continue Reading