Rice Diversity in Different Agricultural Landscapes


The Lowlands

The lowland rice ecosystem in the Upper North consisting of rainfed and irrigated rice has benefited from the Geen Revelution technology sinces the early’ 70 and produced rice for domestic and export market. With the completion of major government irrigation projects since 1970’s and renovation of communual irrigation systems, together with the availability of non-photosensitive rice, for glutinous as well as non-glutinous, the production of dry season rice has became the main cropping alternative.

The Chiang Mai Valley, representing the most intensive and diversified lowland in the Upper North, is characterized by rotational rice-based multiple cropping systems. The common cropping patterns are rice-rice, rice-garlic, rice-vegetables, rice-soybean, rice-onion-rice. It is significant that while much of the double cropping occures within the governmental irrigation schemes, most of the tripple cropping areas lie outside, in communual irrigation or tube-well areas. The Valley is an important rice trading centre in the Upper North.

In the rainy season, over 80 percent of the farmers are growing glutinous rice for home consumption. The system is particularly crucial as food security for the rainfed lowland farm households. The distribution of photosensitive local rice varieties in this ecosystem is still widespread, with common varieties such as Neaw San Pa Tong (widely adapted), Kao Dor (early maturing), Lom Gan (late maturing, lodging resistant) Muei Nong (adapted to cooler environment) etc.

In recent year, the Department of Agricultural Extension (DOAE) has launched the production of good quality rice such as RD6, a glutinous rice derived from irradiated KDML105, which is now becoming popular in the rainfed and irrigated lowland. The promotion of high quality jasmine rice variety, KDML105 by private rice millers and DOAE in the irrigated lowland has offerred opportunity for efficient farmers to allocate part of their rice land to produce jasmine rice for market.

The non-photosensitive rice variety that used to be planted is RD7. The variety was released in 1975, and is still considered to be one of the major non-glutinous rice in the Chiang Mai Valley, although its popularity has been declined in recent years when the promotion of KDML105 has more impact on farmer preference.

The non-photosensitive glutinous rice variety is very limited. A number of local varieties were known to be non-photosensitive and were planted by farmers before the advent of the Green Revolution, but they are now being replaced by RD10 variety, an irradiated derived line from non-glutinous rice, RD1 variety. The RD10 allows the farmers in the irrigated area to adjust their cropping system to satisfy both subsistence and commercial rice production objectives. The recent non-photosensitive glutinous variety released in 1994, Phrae1 (parentage IR 2061-214-3-14/RD4) showed high yielding potential, achieving 7.3 t/ha under high fertilization by Mae Taeng rice farmer in the dry in season, 1997. But the variety has not been extended as intensely as RD6.

With the government promotion of high quality rice production in the irrigated area which is designated as low risk, advanced agricultural zone, and the increasing demand of consumer preference on high quality rice, the areas of high quality rice is increasing. Table 1 shows the area distribution to different rice varieties in 1991.

Table 1.  Percentage of planted area to different rice varieties (1991).

Variety

Whole country

North

Chiang Mai

1 Local

2 RD6

3 RD15

4 KDML105

5 Photosensitive

6 RD21 and RD23

7 Suphanburi60

8 Non-photosensitive

9 Basmati

32.5

25.2

3.7

19.1

8.0

5.6

0.6

5.2

0.1

48.0

15.5

2.4

5.0

9.0

10.0

1.8

8.0

0.3

22.2

29.7

-

19.5

4.5

-

-

20.8

3.3

Total rice planted area 1991 (mha.)

8.83

1.95

0.07

Source: Adapted from Office of Agricultural Economics 1994.

In the Chiang Mai province, the high quality rice KDML105 and its irradiated-derived line, RD6, together with non-photosensitive varieties constitute about 70 percent of rice planted area in 1991. The preliminary 1998 rainy season survey shows an increasing trend of farmer adoption of modern, market-demanded varieties.

Sinces 1990, the Rice Research Institute (RRI) of the Department of Agriculture (DOA) has released a series of high quality lowland rice varieties as shown in the Table 2.

Table 2.  Recommended lowland non-glutinous rice varieties and their reaction to disease and insect pest.

Variety

Parents

year of

Reaction to disease and insect

   

release

BL

BB

RTV

GSV

BPH

GLH

RD1 LT/IR8

1969

S

S

S

S

S

R

RD2 GP152/TN1

1969

S

S

MS

S

S

R

RD3 LT/IR8

1969

S

S

S

S

S

R

RD4 LT/IR8//W1252///RD2

1973

S

S

S

S

R

R

RD5 PN16/Sigadis

1973

MR

MR

S

S

S

S

RD7 C4-63/GR88//Sigadis

1975

MR

R

S

MS

S

R

RD9 LY34/TN1//W1256///RD2

1975

S

VS

MS

MS

R

R

RD11 IR661/KDML105

1977

S

S

S

S

S

S

RD21 KDML105/NMS-4//IR26

1981

S

MR

S

MR

R

MR

RD23 RD7/IR32//RD1

1981

S

R

S

MR

R

MR

RD25 KDML105/IR2061//KDML105/IR26

1981

S

MR

S

MR

R

MR

Suphanburi 60 LT/C4-63//IR48

1987

R

MR

S

MR

MR

R

Phitsanulok90 RD1/BR51-91-6//SPR6726- 134-1-24/IR34

1987

R

R

R

MR

MR

R

Suphanburi90 RD21/IR4422//RD11///RD23

1991

R

MR

MR

R

R

MS

Chainat1 IR13146-158-1/IR15314-43-2-3-3//BKN6995-16-1-1-2

1993

MR

MS

S

R

R

MR

Suphanburi1 IR25393-57-2-3/RD23//IR27316-96-3-2-2///SPR77205-3-2-1-1 /SPR79134-51-2-2

1994

R

R

MR

MR

R

MS

Suphanbiri2 RD23/IR60

1994

MR

R

MR

MR

R

MS

Kao-Chao-Hom Suphanburi SPR 84177-8-2-2-1/SPR 85091-13-1-1-4//KDML105 1997

1997

MS

MR

-

MS

-

-

Klong Luang Nong Mol S-4/IR 841-85-1-1-2

1997

MR

MR

-

-

MS

MS

Note: MR = Moderately resistant, MS = Moderately susceptible

R = Resistant S = susceptible

A number of modern HYVs were tested for their yield performance under high nitrogen level of 100 KgN/ha in the dry season (March-June) 1998 at the MCC experiment station. The 30 days old seedlings were transplanted at plant spacing 20 20 cm with one plant per hill. The fertilizer 16-20-0 at 312 kg/ha was broadcasted at 14 DAT (days after transplanting) and second application with urea at 108.7 kg/ha was top dressed at 35 DAT.

Under high nitrogen level, the modern HYVs could achieve 6 t /ha as shown in Table 3. A number of recently released varieties showed higher potential yields than RD7. These would provide new alternatives for the lowland rice farmers in terms of varietal choice. Farmer interview at Tambol Ban Kad, Mae Wang district which is one of the intensively cropped area in 1997 revealed that the varieties Suphanburi60 and Suphanburi 90 were planted in the dry season for over two years, and showed better yield than RD7.

Table 3. Grain yields of modern HYVs for lowland non-glutinous rice tested at 100 kgN/ha in dry season (March-June) 1998 at the MCC experiment station (300 masl).

Variety

Panicle no./m2

Grain yield
(t/ha)

Maturity (DAT)

1 Phitsanulok60-1

2 Suphanburi1

3 Chinat1

4 Suphanburi90

5 Suphanburi60

6 RD7

7 Suphanburi2

291

271

294

242

244

278

337

6.60

6.35

6.34

6.08

5.79

5.39

4.19

110

101

95

110

98

106

86

LSD 5 %

60

2.18

 

Source: Field experiment at Multiple Cropping Centre, 1998.

However, most of the HYVs are still unknown to the majority of rice farmers in the valley. Since the DOAE is heavily involved in promoting the production of KDML105 or RD6 for better quality rice and higher price.

In the 1998 rainy season, the MCC has provides 300 kg of Chinat1 to a few commercial rice farmers in the Valley for testing.

It can be seen that the local rice varieties are now being replaced by modern HYVs or high quality rice varieties. The diversity of lowland rice within village is declining. However the genetic diversity within the variety is perhaps broader than the local varieties as shown in their parentage and their reaction to diseases and insect pests. The modern HYVs are now developed by multiple crosses and have possessed multiple resistance to disease and insects, having IRRI breeding lines as the main source of resistance (Table 2).

It is noticeable that the numbers of glutinous rice varieties are still far behind that of non-glutinous.

As the consequence of the run-down economy since July 1997, the 1998 growing season has witnessed the return of rice land in the Chiang Mai and the Fang-Mae Ai Valleys. The abandoned fields are planted with recommended rice varieties, such as RD6, KDML105 and a few cases of Phrae1. The varieties used either possess good quality to meet market demand or high yielding potential. Rice cultivation is observed to be more agrochemical intensive and commercialized in the lowland valleys. The adoption of herbicides as a substitute for hand weeding is common among the surveyed rice farmers in the Chaing Mai Valley. Other key pests observed are Golden snail, rice gall midge, white-back plant hopper and rat. The major disease detected at the tillering stage is blast. The RD 6 is susceptible to blast, but the epidemic varies from fields to fields. The farmers are using chemicals for insect and disease control. The Plant Protection Unit of DOAE based in Chiang Mai has ceased its assistance on chemical spraying program. Thus the farmers have to shoulder all the cost of material inputs. At present the average cost of rice production is over 2,000 Baht/rai ($312.5/ha; 1$ = 40 Baht).

It is anticipated that the lowland rice farmers will be more market-oriented and will continue to seek cost-effective production practices, by adopting modern HYVs with diminishing areas of local rice varieties. Since the numbers of non-glutinous HYVs being released are more than the glutinous, the lowland rice farmers would have better choice of non-glutinous varietal selection. The non-photosensitive glutinous variety, Phrae1, showing high yielding potential on-farm and possessing better quality and more resistant to blast than RD10, could offer new option to the rice farmers in the North.

The Uplands

The Upland ecosystem in the upper north occupies about 1.44 mha or 17 percent of total land area of this subregion. Agriculturally, it is rainfed with elevation between 350 to 500 m above sea level. The land form is undulating with slope less than 20 percent. The physical constraints such as erratic rainfall and degrading soil environment have limited the crop choice.

Historically, the area was developed and settled by the landless northern Thais for farming. The development process began with forest clearing and was then followed by upland rice-forest fallow system. Banana was also planted as pioneer crop partly to declare land ownership. Since the area is rainfed and risk-prone, one could observe diversed land-use systems across the landscape depending on potential growing season, from monoculture of annual cash crops, perennial fruit tree orchards, to integrated agroforestry systems.

In Chiang Mai, the cultivation of upland rice in the marginalized rainfed uplands is declining. It has been replaced by important cash crops such as field corn, sweet corn, soybean, etc. The establishment of fruit orchard, from small to large scales, is increasing. The land-use is considered to be more permanent and sustainable, and receiving support from the government institutions. The common fruit tree species include longan, litchi, mango (both for fresh fruit market and for processing), and citrus. The high quality and exotic citrus varieties have been introduced and developed successfully in Fang district, Chiang Mai, thus shifting the citrus growing area traditionally in the Central Thailand to Chiang Mai province.

In terms of planting area, Nan province is the main producing area of upland rice in the Upper North, since Nan has only 2.5 percent (29,440 ha) of the lowland valley. So large proportions of the uplands are used to produce staple food crop.

The upland rice production system takes various forms, but the main patterns include:

    • The crop is incorporated into forest-fallow or bush-fallow system with Varying fallow period. In the forest reserve area, the practice is discouraged by the Forest authority, and non-rice land-use system has been promoted;
    • the crop is planted in rotation with other cash crops on the permanent and intensive land-use system. Legume crops such as soybean, peanut, lab-lab bean, etc. have been introduced by the Department of Land Development (DLD) as part of conservation farming campaign.

The production practice is labour intensive, and farmers use limited external inputs. Occasionally chemical fertilizer is applied at low rate. Insect and disease control is minimum. Farmers would invest in weed control, mainly by hand weeding at least twice before heading. The use of selective herbicide is increasing and common in the village where other annual cash crops are also growing.

The productivity is generally low, averaging less than 1.8 t/ha. The product is for household consumption and not entering the main rice market. The trading (if any) is within the village households.

The diversity of upland rice germplasm has contributed significantly to the local utilization and food supply. Farmers continue depending on the local cultivars for food security. There is no modern HYVs of upland rice or recommended varieties derived by crop breeding program. The present recommended varieties are from pure line selection of local populations. Since the upland rice ecosystem ranging from 350 to 1200 m asl., with wide range of temperature regime and light intensity, the varieties are more environmental specific.

Both glutinous and non-glutinous are found in the upland rice germplasm. The collections from the upper north (Nan, Mae Hong San and Chiang Mai) at the MCC showed the populations are indica type, based on grain morphology. The local northern Thai prefers the glutinous type while the ethnic hilltribe communities prefer the non-glutinous.

The isozyme characterization of upland rice conducted at the MCC had shown that the 68 samples from Nan, Mae Hong Son and Chiang Mai could be differentiated into 41 groups. Twenty-five accessions which had grain yields higher than 2.5 t/ha (ranging from 2.51 to 3.25 t/ha) are tested under four different fertilizer regimes (0, 30, 60 and 90 kg N/ha) in the 1998 rainy season at the MCC experiment station.

As the rainfall in 1998 has been delayed, and considered as drought year by the rice farmers, the phenomenon has affected the cultivation of both upland rice and paddy rice on the mountain environment. The planting of upland rice, Kae Noi variety, in the paddy field under non-submerged condition in 1998 season at Tambol Ban Chan, Mae Chaem district, Chiang Mai province has shown promising growth.

The highlands

The highland ecosystem of the Upper North covers about 6.2 mha or 72 percent of the total land area encompassing watershed areas of the Upper North. The area is inhabited by the ethnic hilltribe communities. The major populations include 9 hilltribes namely: Karen, Hmong, Yao, Lahu, Lisu, Akha, Lua, Htin and Khamu constituting about one millon population. The Karen, which accounts for about 47 percent of the hilltribe population, is the main wet rice cultivator. The community is skillful in managing water resource for production of highland paddy, or transforming upland fields into rice terraces.

Rice is staple food crop and rice sufficiency is the most important household production objcetive. Unfortunately, the production of highland paddy cannot meet the household need, simply because of low productivity and limited paddy fields. Therefore the encroachment of forest land for farming is common particularly in the hamlets where the individual households have no access to paddy fields. The upland rice is planted in the permanent upland fields where trees have long been cleared for farming. The normal practice is two-year fallow rotation, or upland rice-cash crop rotation. The other upland production system is traditional forest fallow where longer period of fallow up to 7 years has been observed.

It is found that all the paddy rice varieties grown on the highland valleys are local or land races, but are all indica type. The modern HYVs as developed for irrigated lowlands could not thrive well under cooler environment and with low light intensity. The Karen has a collection of diversed rice germplasm but has named the planted varieties with only a few names based on plant and grain morphology. The most preferential varieties are Bue Por Moh, Bue Poh Loh, Bue Shaw Me, Bue Wa Po, Bue Pee-I, etc. Work at the MCC has shown that the 49 rice samples collected from the Karen farmers’ fields at Tambol Ban Chan, Mae Chaem district could be clustered into 34 groups based on zymogram patterns. This would indicate that farmers have planted their rice with mixed lines of similar phenotypes. The use of population mixture or blend varieties in other crops such as wheat, oat, etc. has proved to provide stable yield under varying environments.

The Karen has always planted more than one variety of paddy rice for several reasons, for instance hedging against crop failure, eating preference and different uses, sharing seeds within community, planting variety to fit field environments. The variety Bue Pee-I is always planted in the waterlogged low lying area where the strong stem and high tillering ability of the variety has provided better flood tolerance.

However all varieties are not resistant to leaf blast caused by Pyricularia spp. The 1998 rainy season at Tambol Ban Chan has shown the widespread incidence of blast at tillering stage, but the degree of severity varied from fields to fields. In addition, the rice fields were heavily infested with white-back planthopper (Sogatella furcifera (Horvath)), and brown planthopper (Nilaparvata lugens (Stal)). The insect infestation was so serious that the Karen had to spray the fields with insecticides which were not commonly practised in the Karen rice production.

Among the 34 genetically different lines, there were 26 lines showed less photosensitive and could produce yield in dry season ranging from 1.0 to 4.3 t/ha when planted in the lowland environment at the MCC station. However when the selected lines were tested in the highland environment in 1998, the cool temperature in March did not encourage vigorous growth, thus delayed the harvesting time till June, the time when supposed to be the planting of the rainy season rice crop. On-farm studies on effect of delayed planting on local rice yield in 1997 had shown that June was optimal planting time, delaying planting untill August would caused over 60 percent of yield reduction. Therefore double rice cropping, using local non-photosensitive varieties, to provide supplementary rice production for food security, would not be so productive. Early maturity (90 days) and cold tolerance are two important traits necessary for developing dry season rice varietie for the highland environment.

The 1998 season will be considered as the worst year for paddy rice production in Ban Chan studied area. The rainfall sufficient for rice cultivation was delayed until August, and about 20 percent of land lying on the upper terrace were abandoned. Poor vegetative growth due to late planting (in August) would lead to yield reduction. The heavy infestation of white-back and brown planthopper and the incidence of leaf blast would further worsen the paddy rice production. It is evident that the existing rice germplasm as accessible by the Karen community at Ban Chan has limited buffering capacity with delayed planting and was vulnerable to blast and planthopper attack.

The majority of the highland paddy rice varieties showed high yielding potentials when planted in the lowland environment at the MCC experiment station. The overall grain yields were more than double when compared to that grown under highland conditions. A few varieties provided better yields than the modern HYVs.

The typology of rice farming systems in the Chiang Mai province is given in Table 4.

The MCC will continue to maintain the working collections of paddy rice and dryland rice for participatory technology development in three different agroecosystems as discussed above.

(for more information, contact phrek@chiangmai.ac.th)

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