Rainfed lowland rice variety improvement in the wet season in the Lao PDR

Transcription

1 Rainfed lowland rice variety improvement in the wet season 2001 in the Lao PDR Sengpaseuth Rasabandith National Agricultural Research Center, P.O. Box 811, Vientiane, Lao PDR. Abstract Rice is the staple food crop in the Lao PDR. The rice research focuses on three main rice ecosystems, the rainfed lowland, the rainfed upland, and the irrigated lowland environment. The rainfed lowland is the largest in terms of area, production and research activities. Both, photoperiod sensitive and nonphotoperiod sensitive improved glutinous varieties/ lines suitable for the lowland rice environment were evaluated in this 2001 wet season at sites all over the country. The samples are derived either from traditional varieties with good adaptation to the different rice planting areas in the three main agricultural regions (northern, central and southern) or from promising lines from the shuttle breeding programs between Lao-IRRI, Thai-IRRI and IRRI Philippines, which have shown good adaptation to the central and southern regions in previous experiments. In addition, some promising non-photoperiod sensitive glutinous lines selected for dry season irrigated cultivation are also grown under rainfed lowland conditions in the wet season. The replicated yields trial of eight traditional glutinous varieties conducted in five northern provinces revealed six varieties (Luathet, Homdo, Yuando, Homphama, Meuang Nga and Takhiet) with good adaptation to these provinces. The evaluation of 20 photoperiod sensitive glutinous black rice varieties in Vientiane Municipality and Champasak province indicated four promising Kam lines (Kam 7, Kam 11, Kam 14 and Kam 17) with satisfactory yields and maturation periods, which might be suitable for recommendation in central regions of the Lao PDR. The experiment conducted at four sites in Northern Laos as a result of the northern conference in October 2001 indicated large variations between different locations and the 12 traditional glutinous varieties tested: Khaomeuay proved more suitable for Luang Namtha, Meuang Nga for Oudomxay and Ikhao for Huaphanh and Xiengkhoang. The average maturation period in Huaphanh and Xiengkhuang (158 days) was markedly longer than in the other two provinces, probably due to the high elevation (900 m.a.s.l). Grain yields of eight photoperiod non-sensitive glutinous promising lines at eight locations in the Lao PDR, showed the average yield of four lines: IR TDK-2-3-B-, IR TDK- 1-2-B-, IR70824-TDK-44-2-B-1-2- and IR70824-TDK-5-B-1- being better adaptation and hopefully release in the future for non-photoperiod glutinous varieties. Three lines: IR B-1-2-, IR TDK-B-B- and IR TDK-B-B achieved higher yield stability than the control TDK 4 and can hopefully be released to farmers in the near future. Key words: Lao PDR; rice improvement; photoperiod sensitive; early maturity; medium maturity; photoperiod non-sensitive, black rice, glutinous rice; TDK 1; TDK 4. 9

2 3 4 ñ ²ñ À í Õ±ö à ì1 2 ø±ö 2001 µøè ì3 4 ö ñ ¹ Ó À í3 4Ä É 3 4 À ñ º3 4¹3 4 ¹ìñ º 1 2Àê, í É 3 4À í3 4Á È Ä ÉÀ Ã È 3 4 ì1 2 ö 3 4 ø À ñ ¹ìñ : À í Õ±ö, À í3 4Ä»È Áì1 2 À í ö ì ê ø À í Õ±ö Ä É Àºö3 4À ºê¹ì3 4 ºñ ñ Î ²Éº êñ ö 1 2ìò Áì1 2 ò í É 3 4 ªÈ3 4 Å. Á ²ñ, 3 4 ²ñ À í3 4Î1 4 êñ Ä Á Áì1 2 ÒÄ Á Ä É«õ à Éê 1 2Àê È Ã¹È Á È Á ²ñ ² À õº ê ñ ªö Ä É óã ¹ì3 4 êéº «ê ø À í3 4²3 4 à 1 2Àê Áì ²ñ Î êä É 3 4 ìø 1 2 ö Ä ÉÀ»ñ 3 4 ñ Àìõº ²3 4 à Áì1 2 ªÈ Àê À : 1 2«3 4 ñ í É 3 4À í Å 3 4 ê³óìò ò Áì Àê Äê, ÁªÈ ð ó 3 4 ²ñ Î Á È À²º ñ Àìõº ìñ À º Ä 3 4 ö ì ê3 4 à ì1 2 ø±ö. 3 4 êö ìº 1 4 ê1 4 ö 1 2ìò º Á Á ²ñ À í3 4Î1 4 ² À õº à ¹É3 4Á : º ö Ä, 1 4, ¹ì ² , ¹ö ²ñ Áì1 2 ¹ì Õê3 4 Á È Ä É óêñ ¹ö Á ²ñ À : Àìõº Á», ¹º ð, ð, ¹º ²1 2 É3 4, ª Áì1 2 À õº ø Áì1 2 ñ ªö Ä É óµøè ñ 3 4 Á È3 4 ÀÏõº ñ À í3 4ÀÏõº Áì1 2 À í3 4Ä È Éº êä ÉÀ ñ ªö µõ. êö ìº 1 4 ê1 4 ö 1 2 ìò À í3 4 Ô ²ñ ê Á² 1 2 º Áì ñ Ä É ó 3 4 ²ñ À : 3 4 ²ñ êó 7, 11, 14 Áì Á È ó ö 1 2ìò ɺ É3 4 óã À Á² È Á 3 4 ñ ö 1 2 ìò ɺ É3 4 ªÔÀ º 3 4 Á Á ê ì3 4 à À ì3 4À í3 4ºº º È º3 4 Ä É È1 4 Á ÁªÈ 133 À«ò 162 ñ. êö ìº 1 4 ê1 4 ö 1 2ìò 12 Á ²ñ À í3 4Î1 4 ² À õº êà ñ 3 4 êö ìº À ó 3 4 ò à º 1 2 À í3 4ê Á ²3 4 ÀÎõºÃ À õº 10 ó 2000, Ä É À¹ñ È3 4 Á ²ñ À í3 4ÀÏõº ÀÏ ö ñ Á ¹ì Õê3 4, À í3 4À õº 3 4ÀÏ ö à Á º ö Ä Áì1 2 À í3 4º 3 4 ÀÏ ö à Á ¹ö ²ñ Áì , º3 4 È ¹ì Á È 3 4 µøèà ²3 4 ÀÎõº º ÀìÈ 158 ñ º3 4 ó ö 1 2êö 3 4 ì1 2 ñ 3 4 ø Áì1 2 óº Àµñ È 3 4. êö ìº 1 4 ê1 4 ö 1 2ìò Á 3 4 ²ñ À í3 4Î1 4 ÒÄ Á µøè 8 à ê 1 2Àê, Ä É ó ²ñ : IR TDK-2-3-B-, IR TDK-1-2-B-, IR TDK-44-2-B-1-2- Áì1 2 IR TDK-5-B ñ ªö Ä É ó Áì1 2 ó 3 4 ¹ ñ 1 2ºº À ñ Á ²ñ À í3 4Î1 4 à º ö. êö ìº 1 4 ê1 4 ö 1 2ìò Á 3 4 ²ñ À í3 4Î1 4 Ä Á µøè 8 à ê 1 2Àê, Ä É ó ²ñ : IR B-1-2-, IR TDK-B-B- Áì1 2 IR TDK-B-B ñ ªö Ä É ó Áì1 2 ó 3 4 ¹ ñ 1 2ºº À ñ Á ²ñ À í3 4Î1 4 Ä Á à º ö. 10

3 Introduction Agriculture is one of the most important economic sectors of the Lao PDR. It currently contributes more than 50% to gross domestic product and accounts for 86% of the total labour force. Its contribution to national export earnings has been estimated at approximately 40%. Among the agricultural sub-sectors, rice production is the single most important activity in the domestic Lao economy. As rice is the staple food crop in the Lao PDR, the research on rice is closely linked with national food production as well as with sustainable agriculture and the reduction of slash-and-burn or shifting cultivation. Among the three rice main growing environments, the rainfed lowland, the rainfed upland, and the dry season irrigated lowland, the rainfed lowland environment is the largest in term of area, accounting for 68% of the total rice growing area (801,255 ha) in the year 2001, followed by the rainfed uplands (20%) and the dry-season irrigated environment with a further (13%). The total rice production has reached 2.3 million tons, with 69% of the production coming from the rainfed lowland rice environment. Production from the upland rice and irrigated lowland environments accounted for 12% and 19%, respectively. Due to the dependence on the rainfed environment, the annual production can vary greatly from year to year, reflecting the impact of periodic flooding and drought. In order to bring greater stability to production, the government of the Lao PDR commenced a program of rapid development of irrigation facilities in In the five-year period from 1996 to 2000, the area of dry-season irrigated rice increased 5-fold, from 18,000 ha to 102,000 ha which was reflected in a 6-fold increase of production in this environment (from 75,000 to 390,000 tons) and the achievement of national rice self-sufficiency in 1999 with total production of 2.1 million tons. In the year 2001, more than 50% of the rainfed lowland production and 60% of the irrigated production was based on the adoption of improved production technologies and new improved varieties. In 1993, only three Lao improved varieties were available for the lowland rainfed and irrigated environment: Tha dok kham 1 (TDK 1), Tha dok kham 3 (TDK 3) and Phone Ngam 1 (PNG 1). These varieties and the related improvements in cultivation practices were widely adopted. Recently, six additional improved varieties, Tha dok kham 2 (TDK 2), Tha dok kham 4 (TDK 4), Tha dok kham 5 (TDK 5), Phone Ngam 2 (PNG 2), Thasano 1, (TSN 1) and Namtane 1 (NTN 1) were released. With the exception of TDK 4, which is photoperiod sensitive, these varieties are all high yielding in both the rainfed lowland and irrigated environments. About 13 promising glutinous and non-glutinous lines from previous results with good adaptation to special regions of the Lao PDR and high yield potentials up to 4 t/ha under medium soil conditions (farmers practice) are expected to be ready for release in the next few years. Some of those varieties reached up to 5 t/ha in the on-farm trials. The main objectives of the rainfed lowland rice varietal improvement are the development of varieties with: Early to medium maturity (ca days), suitable for both lowland and irrigated environments High yield potentials for glutinous and non-glutinous endosperm types and good adaptation to specific regions of the Lao PDR Good eating and milling quality and slender grains (long grain) Resistance to major pests and diseases 11

4 Materials Materials and methods Promising lines from the shuttle breeding program between the Lao Rice Research Program/Lao-IRRI, Thailand, Vietnam and the Philippines, as well as some traditional varieties from the Rice Gene Bank of the National Agricultural Research Centre (NARC) with good adaptation to the Lao conditions were used in the breeding programs. Inorganic fertilizers (15:15:15 or 16:20:00 and 46:00:00 NPK) were used in the experiments. Methods The experiments of the National Rice Research Program are conducted continuously in the three agricultural regions of the country (north, central and south) using three consecutive types of experimental techniques: 1. Observation Yield Trials (OYTs), 2. Replicated Yield Trials (RYTs) and 3. Demonstration Plot Tests (DPTs). The OYTs are set up as modified Random Complete Block (RCB) designs with two replications and a plot size of 1 x 5 m and the RYTs as RCB layouts with four replications and a plot size of 2 x 5 m. DPTs are conducted without replication and serve to compare the new varieties with welladapted local varieties. The plot size depends on their location but have a minimum size of 5 x 10 m. The soils of the experimental sites selected have to be representative of the main rice planting areas of that region. The soil preparation methods used as well as the time of transplanting (from May to June) follow the farmers usual practice. The varieties are transplanted at a hill spacing of 20 x 20 cm and fertilizer is applied at a rate of and kg/ha equivalent of N : P 2 O 5 : K 2 O in the wet season (WS) and in the dry season (DS), respectively. No pest control was undertaken during the experiments except in case of heavy damage by golden apple snail after transplanting. For yield measurement, the standard measurement of IRRI was used: Yields were adjusted to 14% moisture content, maturity from seeding to flowering 50% plus 30 days, number of panicle per hill and plant height. 100-MC (a)g m 2 Yield (kg/ha) = * * % 1000 g (b) m 2 MC = Moisture content of sample measurement (a) = Grain yield of the sample / plot (b) = Sample area / plot Results and discussion Replicated Yield Trials of eight traditional glutinous varieties in the northern provinces Identical replicated yield trials with eight traditional glutinous varieties were conducted in five provinces (Oudomxay, Xiengkhuang, Luang Prabang, Huaphanh and Luang Namtha) representative of the northern rice planting areas. Of the eight traditional varieties evaluated in this experiment, two varieties, Khao Meuay and Kainoy, which are well adapted to the northern provinces, were used as controls (Table 1). The results after one season indicate that the yields of these eight traditional varieties vary greatly within as well as between locations (Table 1). The lowest average yields (1626 kg/ha) were achieved in Luang Prabang due to heavy damage by rats. Highest yields were achieved in Luang Namtha with an average 12

5 yield of 3922 kg/ha. The Huaphanh site had only five varieties in the experiment because of poor germination of three varieties and a lack of experience by some researchers in addition to rat damage in the seedlings stage. The range of yields was very large in Oudomxay province ranging from 2180 kg/ha (Kaynoi, control) to 4912 kg/ha (Meuang Nga). The two control varieties, Kainoy and Khao Meuay produced significantly lower yields than all other varieties tested in that location with only 2180 kg/ ha and 2518 kg/ha, respectively. This showed clearly that the six tested traditional varieties (Luathet, Homdo, Yuando, Homphama, Meuang Nga and Takhiet) are better adapted to conditions in Oudomxay province than these two controls. This experiment was the final test for these eight traditional varieties, which indicated that almost all of them showed good adaptation to the northern provinces and are suitable for recommendation to farmers in the northern provinces. The assessment of their eating quality will be necessary and will be undertaken in a different next study. Table 1. Grain yields of Replicated Yield Trials of eight traditional glutinous varieties in the wet season 2001 in five provinces of the northern Lao PDR. Variety Oudomxay Xiengkhuang Luang Prabang Huaphanh Luang Namtha Ave kg/ha Luathet 4045 c 3798 ab 1378 c 2583 a 3483 a 3057 Homdo 3070 d 3300 ab 1366 c a 2799 Yuando 4068 c 4016 ab 1439 bc 2709 a 4053 a 3257 Homphama 4166 bc 3689 ab 2150 a a 3548 Meuang Nga 4912 a 4379 a 1413 c 2457 a 3678 a 3368 Takhiet 4745 ab 3813 ab 1664 abc 2457 a 3800 a 3296 Khao Meuay (control) 2518 de 3114 b 1902 ab a 2921 Kainoy (control) 2180 e 3503 ab 1694 abc 2583 a 4567 a 2905 Ave CV 11% 18.5% - 7.4% 17.9% F-test ** ns - ns ns LSD 5% LSD 1% Sowing: 18/6/2001 8/6/ /6/2001 1/5/ /6/2001 Transplanting: 13/7/2001 7/7/ /7/2001 1/6/ /7/2001 Fertilizer level: Means followed by common letters are not significantly different at the 5% level by DMRT. Grain yields and maturities of Replicated Yield Trials of 20 photoperiod sensitive glutinous black rice varieties in Vientiane Municipality and Champasak province The yields of 20 photoperiod sensitive glutinous black rice varieties from the Lao Rice Gene Bank were compared at two experimental sites in Vientiane Municipality and Champasak province. The high yielding improved line IR46346-KKN , which is not a black rice variety, was used as a control. In Vientiane M. the yields ranged from 1789 kg/ha to 2895 kg/ha, with Kam 18 producing the lowest and Kam 14 the highest yield, followed by Kam 7 with 2719 kg/ha (Table 2). There were four Kam lines, Kam 7, Kam 11, Kam 14 and Kam 17 that gave significantly higher yields than the control IR KKN In contrast to the Vientiane site, yields in Champasak province varied only little, ranging 13

6 from 1443 kg/ha (Kam 8) to 2065 kg/ha (control). The yield of Kam 8 was the only one, which was significantly different from that of the control IR46346-KKN , due to heavy damage by rice bug during the flowering stage which led to significant yield reduction. The days-to-maturity ranged from 133 to 162 days within the two experimental locations and was generally much shorter in Champasak than in Vientiane M. The variation between early and late maturity was about three to four weeks. Table 2. Grain yields and maturities of Replicated Yield Trials of 20 photoperiod sensitive black glutinous rice varieties during the wet season 2001 at NARC and Champasak province. Vientiane Municipality Champasak Ave Variety Yield Mat Yield Mat kg/ha days kg/ha days kg/ha Kamdeng 2062 cd ab Kam cd ab Kam cbe ab Kam cd ab Kam a ab Kam cde b Kam ab ab Kam a ab Kam cde ab Kam cde ab Kam a ab Kam cd ab Kam a ab Kam de ab Kam bc ab Kam ab ab Kam ab ab KKNLR a IR46346-KKN (control) 2195 bcd a Ave CV 11.50% 19.20% F- test ** ** LSD 5% LSD 1% Sowing: 15/6/ /6/2001 Transplanting: 20/7/ /7/2001 Fertilizer level Means followed by common letters are not significantly different at the 5% level by DMRT. Grain yields and maturities of Replicated Yield Trials of 12 traditional glutinous varieties in four northern locations in the Lao PDR This experiment was initiated as a consequence of the northern conference held in Luang Namtha province in October The experiments were conducted in four provinces: Oudomxay, Xiengkhuang, Huaphanh and Luang Namtha. The yields of 12 traditional glutinous rice varieties from the Lao Rice Gene Bank were compared to Kainoy, a variety well adapted to Huaphanh province. Their yields varied greatly within one location when compared to Kainoy as well as between locations (Table 3): the highest site average was achieved in Huaphanh province with 5310 kg/ha compared to 3710 kg/ha in Luang 14

7 Namtha, 3526 kg/ha in Xiengkhuang and only 3180 kg/ha in Oudomxay. In Luang Namtha province yields ranged widely from 3040 kg/ha to 4680 kg/ha. Khaonong gave the lowest yield and Khao Meuay achieved the highest, followed by Takhiet Do with 4432 kg/ha. This indicates that these eleven traditional varieties are equally well adapted to the conditions in Luang Namtha as Kainoy (control). In Huaphanh province, most varieties achieved yields comparable to that of the control variety Kainoy (5366 kg/ha), but one variety, Ikhao, stood out with a significantly higher yield (6536 kg/ha). The lowest yield was achieved by Yuando with 4789 kg/ha. The days to maturity ranged from 132 to 146 days with a variation of about two weeks. In Huaphanh and Xiengkhuang the maturation period was 158 days which was markedly longer than in Oudomxay 140 days) and Luang Namtha (139 days). Table 3. Grain yields and maturities of Replicated Yield Trials of 12 traditional glutinous varieties in the wet season 2001 in four northern provincs of the Lao PDR. Variety Luang Namtha Oudomxay Huaphanh Xiengkhuang Ave Yield Maturity Yield Maturity Yield Maturity Yield Maturity Yield kg/ha days kg/ha days kg/ha days kg/ha days kg/ha Luathet 4148 ab a bcd abc Homdo 3262 ab ef cd bc Yuando 3594 ab de d abc Homphama 2851 b cd bcd bc Meuang Nga 3630 ab a bcd ab Takhiet Do 4432 ab g bcd abc Ikhao 3074 ab bc a a Khaonong 3040 b ef b c Bongleuang 3119 ab cd b bc Khaola 4258 ab f bcd abc Khao Meuay 4680 a ab bcd bc Kainoy (control) 4429 ab f bc c Ave CV 25.8% 12.1% 5.6% 15.3% F-test ns ** ** * LSD 5% LSD 1% Sowing: 24/6/ /6/ /5/2001 5/6/2001 Transplanting: 15/7/ /7/2001 6/7/ /6/2001 Fertilizer: Means followed by common letters are not significantly different at the 5% level by DMRT. 15

8 Table 4. Grain yields of Replicated Yield Trial of eight photoperiod non-sensitive glutinous promising lines in the central and southern Central and Southern Provinces of the Lao PDR. Variety Vientiane Vientiane M Champasak Saravane Borikhamxay Attapeu Khammuane Savannakhet Ave kg/ha IR TDK-3-1-B c 3429 a 3153 ab 3405 a 4412 bc 2464 ab 2087 c 3544 a 3377 IR TDK-2-3-B a 3378 ab 3625 a 2912 bc 3918 de 2928 a 2614 b 3495 a 3446 IR TDK-1-2-B ab 3362 ab 3934 a 3456 a 4577 b 2903 a 2776 ab 3435 a 3525 IR B-2-1-TDK-1-B bc 3664 a 3482 ab 3205 ab 3883 de 2055 ab 2152 c 3617 a 3402 IR70824-TDK-44-2-B ab 3589 a 3825 a 3302 a 4115 cd 3150 a 2580 b 3489 a 3520 IR68102-TDK-B-B e 2456 c 3690 b 2789 c 4472 bc 1416 b 1506 a 3077 a 2812 IR70824-TDK-5-B a 3633 a 3052 ab 3162 ab 3651 e 2253 ab 2918 ab 3570 a 3440 TDK 1 (control) 2897 d 3106 b 3781 a 3374 a 4963 a 2991 a 3109 a 2831 a 3145 Ave CV 7.8% 5.7% 15.4% 6.9% 4.7% 27.5% 9.8% 11% F-test ** ** * ** ** * ** ns LSD 5% LSD 1% Sowing: 11/6/ /6/ /6/2001 3/6/2001 2/6/2001 1/6/2001 1/6/2001 1/6/2001 Transplanting: 9/7/ /7/ /7/2001 2/7/ /6/ /6/ /6/ /6/2001 Fertilizer level ? Means followed by common letters are not significantly different at the 5% level by DMRT. 16

9 Grain yields of Replicated Yield Trials of eight photoperiod non-sensitive glutinous promising lines in at eight locations in the central and southern agricultural regions of the Lao PDR Seven promising photoperiod non-sensitive glutinous lines from the shuttle-breeding program between Lao-IRRI and Thai-IRRI, which had been selected at NARC in previous RYTs, were selected for testing their adaptive ability to the main rice planting areas in the Lao PDR. The yields of these lines were compared with the Lao improved high yielding variety TDK 1, which is well adapted to central and southern regions. The experiment was conducted in eight provinces: Vientiane Municipality, Vientiane, Champasak, Saravane, Borikhamxay, Attapeu, Khammuane and Savannakhet. The yields of these seven promising lines showed significant statistical differences compared to the control TDK 1 in almost every location except Savannakhet (Table 4). The average yield was highest in Borikhamxay province with 4249 kg/ha and lowest in Khammuane province with only 2468 kg/ha. In Borikhamxay, yields ranged from 3651 kg/ha to 4963 kg/ha with the highest yields recorded for the control TDK 1 followed by IR TDK-1-2-B- (4577 kg/ha) whereas the lowest yield was from IR TDK-5-B-1 with only 3651 kg/ha. In Savannakhet province, all promising lines tested against TDK 1 achieved higher yields than TDK 1 although the differences were not statistically significant. The results indicated that all seven promising lines tested are equally well adapted to the central and southern regions as the control TDK 1 with the exception of IR TDK-B-B which consistently showed an average yield lower than the control TDK 1. This experiment will be repeated for a second season in the 2002 wet season. Grain yields of Replicated Yield Trials of seven promising photoperiod sensitive glutinous lines in eight locations in the central and southern agricultural regions of the Lao PDR The yields of seven promising photoperiod sensitive glutinous lines from the shuttle-breeding program between Lao-IRRI and Thai-IRRI, which had been selected at NARC in previous RYTs, were selected for testing their adaptive ability to the main rice planting areas in the Lao PDR. These lines were compared to the photoperiod sensitive TDK 4, which is well adapted to the wet season environment. The experiment was conducted in eight provinces: Vientiane Municipality, Vientiane, Champasak, Saravane, Borikhamxay, Attapeu, Khammuane and Savannakhet. The results after one season indicate that the yields of these seven promising lines were significantly different compared to that of TDK 4 in almost all locations (Table 5). The average yield was lowest in Vientiane M. with 2540 kg/ha and highest in Vientiane province with 4218 kg/ha. Yields ranged widely in Vientiane Province from 3152 (IRUBN4-TDK ) to 4836 kg/ha by TDK B-1-3 followed by TDK B-1-1- with 4663 kg/ha. All promising lines except two (IR68105-TDK-B-Band IRUBN4-TDK-1-2-1) had yields higher than the control variety TDK 4 (4112 kg/ha). In Vientiane M., all seven promising lines got statistically significant higher yields than the control TDK 4. In the other six provinces (Champasak, Salavane, Borikhamxay, Attapeu, Khammuane and Savannakhet) the average yields did not differ greatly and ranged from 2640 to 3585 kg/ha. These yields indicate, that all seven promising lines are better adapted to these two regions (central and southern regions) than the control variety TDK 4. As the trial in wet season 2001 was the first, the assessment of these lines will be extended for a second in the wet season 2002 and a final season in the wet season

10 Table 5. Grain yield of Replicated Yield Trials of eight photoperiod sensitive glutinous promising lines in the WS 2001 at the central and southern provinces of the Lao PDR. Variety Vientiane Vientiane M Champasak Saravane Borikhamxay Attapeu Khammuane Savannakhet Ave kg/ha TDK B a 2389 cde 3292 bc 3281 a 3511 a 3189 bc 2611 ab 3358 a 3286 TDK B abc 2724 abc 3536 bc 2706 bc 3210 b 3397 bc 2967 ab 3194 a 3265 TDK B a 2155 de 3482 bc 3284 a 3664 a 3156 bc 2873 ab 3086 a 3317 IR TDK-B-B c 2600 bc 3486 bc 2995 ab 2984 c 3291 bc 3100 a 3387 a 3216 IRUBN4-TDK d 2521 bcd 4115 a 3154 a 3301 b 3478 bc 2609 ab 3442 a 3221 IRUBN8-TDK bc 2855 ab 3656 ab 2473 c 3218 b 3522 b 2983 ab 3562 a 3299 IR68102-TDK-B-B ab 3070 a 4074 a 2946 ab 3679 a 4366 a 2393 b 3129 a 3533 TDK 4 (control) 4112 bc 2005 e 3041 c 3185 a 3335 b 2682 c 1581 c 1666 a 2701 Ave CV 7.9% 9.8% 9.5% 6.9% 2.8% 14.8% 14% 14.1% F-test ** ** ** ** ** ** ** ** LSD 5% LSD 1% Sowing: 6/6/ /6/ /6/2001 3/6/2001 2/6/2001 8/6/2001 1/6/2001 1/6/2001 Transplanting: 9/7/ /7/ /7/2001 2/7/ /6/ /6/ /6/ /6/2001 Fertilizer level: Means followed by common letters are not significantly different at the 5% level by DMRT. 18

11 Conclusions Because rice is the staple food crop in the Lao PDR, the national rice research focusses on the rainfed lowland environment, which occupies the largest area. Both photoperiod sensitive and photoperiod nonsensitive improved glutinous and traditional glutinous varieties were used for the experiments in this 2001 wet season. The RYTs in the northern provinces comparing eight traditional glutinous varieties with the well adapted and popular traditional varieties, Khao Meuay and Kainoy, indicated six varieties (Luathet, Homdo, Yuando, Homphama, Meuang Nga and Takhiet) with comparable yields to the two controls. Grain yields and days to maturity of 20 photoperiod sensitive glutinous black rice varieties were evaluated in Vientiane Municipality and Champasak province. In Vientiane Municipality four Kam lines (Kam 7, Kam 11, Kam 14 and Kam 17) showed good yields and might suitable for recommendation to farmers in central parts of the country. In Champasak province the control variety IR46346-KKN achieved the highest yield, because heavy damage by rice bug during the flowering stage had led to a general reduction of the yields. The maturity periods ranged from 133 to 162 days with a variation of about 3-4 weeks between the early and late maturates. The evaluation of grain yields and maturities of twelve traditional glutinous varieties at four locations in the Lao PDR indicated wide yield differences between locations. Khao Meuay was more suitable for Luang Namtha conditions, Meuang Nga for Oudomxay, Ikhao for Huaphanh and Xiengkhuang conditions respectively. With 158 days, average maturity was longer in Huaphanh and Xiengkhuang provinces than in the other two provinces. average maturity of 158 days were later maturity than other two provinces, most probably due to the higher elevation. The comparison of grain yields of seven photoperiod non-sensitive glutinous promising lines at eight locations in the Lao PDR showed that the yields of all seven promising lines were significantly different compared to TDK 1 (control). Four lines (IR TDK-2-3-B-, IR TDK-1-2-B-, IR TDK-44-2-B-1-2- and IR TDK-5-B-1-) achieved high average yields and can hopefully be released in the near future. The comparison of seven photoperiod sensitive glutinous promising lines at eight locations in the central and southern regions showed good grain yields comparable to the control TDK 4 in all locations. Three lines (IR B-1-2-, IR TDK-B-B- and IR TDK-B-B-31-1-) achieved higher yields and better yield stability than the control and can possibly be released to farmers in the near future. 19

12 Acknowledgements On behalf of the Rice Improvement Unit and Food Crops the author writing for the Lao-IRRI Annual Technical Report 2001, would like to show his gratitude to all whom it may concern, especially, the donor, the Swiss Agency for International Development and Cooperation (SDC), through the Lao-IRRI Project who supported all facilities and rice research. The assistance of the following is gratefully acknowledged: Dr. Renate Braun and Mr. Philip Gibson who gave advice, instruction and took responsibility for this report. Without their help, this report would not have been completed. References Lao-IRRI, Annual Technical Report of the National Rice Research Program and Lao-IRRI Project, p Lao-IRRI, Annual Technical Report of the National Rice Research Program and Lao-IRRI Project, p