Proceedings of the UNESCO - University of Tsukuba International Seminar on Traditional Technology for Environmental Conservation and Sustainable Development in the Asian-Pacific Region, held in Tsukuba Science City, Japan, 11-14 December, 1995.
Editors: Kozo Ishizuka, D. Sc. , Shigeru Hisajima, D. Sc. , Darryl R.J. Macer, Ph.D.
Keywords: Rice culture, LISA, mixed culture of many cultivars, Azolla,
no-till and direct broadcasting
Especially, it is expected that increase of environmental and food pollution possibly by increased use of fertilizers and pesticides will be faced with difficulty in practicing the idea of Green Round (GR). The objective of this paper was to suggest in developing LISA program aiming at the future direction through the wisdom from the ancient farming system of Korea.
1) Paddy Fields (Kim et al; 1994)
* Function as natural dams: ability to control flooding, build up of groundwater,
cooling down of the atmosphere during the hot season.
* Function as environmental conservation : prevention of soil erosion, decrease of
groundwater contamination, purification of water, cleaning of air.
* Function as ecological conservation : supply of food, preservation of natural scenery,
buffering of pollution, control of global warming
2) Rice Plants
* Oldest staple food supply (productivity)
* Prevention of soil acidification
* Crops not sensitive to soil textures and fertility
* Formation of cultural background with rice and straw (traditions)
The role of agro-ecological cultures (Fig. 1) will probably expand as there is increased perception of the economic and environmental costs of heavy reliance on agricultural chemicals (Horwith, 1985).
Figure 1 : The potential performance of Green Revolution technologies (high-input agriculture) and agro-ecological technologies (low-input agriculture) along a gradient of natural resource and socioeconomic conditions affecting peasant farming systems (Altieri and Anderson 1986)
At that time rice growing was already prevalent in the country Han, but was prepared for a disaster on the basis of dry farming. Crops resistant to the disaster were mixed planted in order to secure the minimal food, although the kind of crops was not the same.
Mixed planting of resistant crops to the disaster was recommended in many farming books at the ancient Chosun (1400-1800 A.D). Also, the farming system at that time was based on dry farming which was probablyoriginated from China.
A farming book (----------- ) released in 1400s was found that the planting ratio of 2 rice cultivars, 2 millet, and 1 red bean was recommended in order to overcome the flood and drought, by which we do not lose everything at once.
This mixed planting method was frequently found in the farming book released in 1800s
(--------------- ), so that the farming technology of Chosun dynasty was known to us on the basis of this method for prevention of various disaster of meteorology and biology, especially the counter-measure against insect pests were importantly described. The book says that everything will not lose by flood, drought, wind and insects if any crops may tolerate from the disasters.
Also, in another farming book (---------------- ) it is mentioned that there are many upland rice... (omitted) .... These kinds of crops would be better broadcast in wide furrows and mixed with seed of millet or red bean.
In this case more encouragements on mixed planting or inter-cropping were made with wide furrows in order to cope with the disasters. This technology of farming was found not only in the age of the ancient China and Korea, but in many other countries where the primitive of ecological farming systems were practiced. Two reports by Matterson et al. (1980) and Harlan (1976) also explains the facts and effects of such a similar farming technology.
As for regular exchange of photoperiod-sensitive rice varieties adapted to differing environmental conditions in Latin American tropics, the temporal, spatial and genetic diversity resulting from farm-to-farm variations in cropping systems confers at least partial resistance to pest attack. Depending on the degree of diversity, food web interactions among the insect pests of rice and their numerous natural enemies in paddy fields can become very complex, often resulting in low but stable insect population. This is why any one variety begins to suffer from pest problems if grown continuously on the same land for several years (Mattesen et al, 1984).
Also, Harlan (1976) stated in his report on "Genetic resources in wild relatives of crops" as follows.
Traditional agroecosystems are genetically diverse. Southeast Asia some lines are resistant or tolerant to certain races of pathogens and some to other races. The resulting genetic diversity confers at least partial resistance to diseases that are specific to particular strains of the crop and allows farmers to exploit different microclimates and derive multiple uses from the genetic variation of a given species.
The minimization of input for energy, fungicide, insecticide, fertilizer, herbicide and labour would be achieved by use of broadcasting resistant crops in no-tilled paddy and inoculation of Azolla that is a source of nitrogen supply, has temperature control in summer, and has effect of weed control. By doing this system, the following achievements are obtained;
First, maximization of rice productivity (labour productivity),
Second, maximization of ecological potential of paddy,
Last, improvement of rice quality (taste, less contamination) and conservation of ecological functions of paddy.
In 1960s intensive research had conducted by Rural Development Administration and Agricultural Colleges for breeding of resistant cultivars, including germinability under cool conditions, short growing period of nursery bed, growth type, resistant to fertilizers, resistant to diseases, resistant to insects, resistant to cool temperature, and to salt, tolerance to extremes, antilodging, quality, etc(Table 1). Thus, in Korea specific cultivars could be selected from the existing ones in each environment and problem.
2. Validity of mixed planting of resistant cultivars.
Kiyosawa and Shiyomi (1972): In order to examine the effectiveness of use of multi-line variety system, simulations of disease increase in the pure stand of susceptible variety and in the mixed stand of susceptible and resistant varieties were tested by the dispersal nature of pathogens. As results, the effect of mixing resistant plants decreased the dispersal gradient, and double of multiple infection and the decrease of healthy area of susceptible plants were presumed to play an important role in flattening of dispersal distribution curve in the actual field as well as contamination from outside sources and the increase of infection generation.
Kiyosawa (1972): The mixture and rotation cultivations of resistant varieties were theoretically compared as to which more effective usage is for controlling plant disease. And as a result, it was emphasized that the nature of daily increase of disease is necessary to be analyzed especially in relation to the presence or absence of density effect, in order to know the relationship. The data on cumulative spore numbers at Toyoshina, Nagano prefecture showed that there was no or a little density effect in disease increase at the conditions.
Koizumi and Tani (1995): The effect of mixed planting was recognized on suppression rice blast disease by mixing different isogenic lines which are different from the true resistance. Also, suppression of blast disease was similar to that of fungicide application when strong and intermediate cultivars of blast resistance were mixed planted.
Based on the research, considerable control of the disasters from meteorological and biological points could be achieved by mixed planting, which will lead no use of pesticides and less control of seeding data. However, minimum use of pesticides would be required to apply around heading stages of rice in order to control biological disasters which are directly related to rice yield.
3. Competition among rice cultivars
In order to investigate varietal competition effects on yield of rice, three leading varieties were grown in pure and mixed stands with different combinations. As results, no significant difference was found in grain yield between varietal mixture and pure stands, and the performance of mixtures were determined by the balance of the increment of better competitor and the deficit of the poorer competitor.
4. Yield compensation for stand reduction
Y= 312.3 + 18.4 X1 + 5.3 X2 - 0.16 X3 (where, X1 < 12.1 <= X2 < 19.1 < X3) R2 = 0.99**
However, based on the regression equation, no significant yield reduction can be expected from rice density at 12.1 stocks/m2, which is 54 to 60% less than the standard. Additionally, rice yield even at 8 stocks/m2 of density which is 70 to 74% loss would be compensated if the fertilization level is increased 1.28-fold (Guh et al. 1985B).
5. Effect of no-tillage
This method has also been adopted to the infant rice seedling for the rice production. After transplanting of infant rice seedling, there are more in missing hills than tillage field (Table 3). However, this is recovered at the maximum tillering stage of the rice plant and thus there is no significantly different final yield production between no-tillage and tillage cultivation. There was no different in heading stage and in yearly variance of soil hardness at both tillages. Also there was an improvement in chemical properties of the surface soil under no-tillage cultivation than that under tillage cultivation of the rice plant (Table 4).
6. Effect of labour saving by direct broadcasting
Figure 2 : Polygonal regression relations of paddy rice yields (kg/10a) as affected by transplanting density.
Use of Azolla
Figure 3 : Changes of taste and texture of cooked rice as affected by mixed cropping of different cultivars.
8. Improvement of rice quality by mixed cultivars
When Tongil rice was grown in large acreage, there suggested. a way to improve the taste by cooking with glutinous rice. In this respect, Park and his collegues (1993) tried to grow various rice cultivars in the same field in order to see the changes of eating taste. The results was that eating quality(taste and texture) of the cooked rice was rather improved by mixing of various varietal combination than any one variety. Thus, the eating taste and quality of the harvest can be possibly improved by mixed cultivation of various cultivars (Fig. 3).
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