Irrigated rice variety improvement in the dry season in the Lao PDR

Transcription

1 Irrigated rice variety improvement in the dry season in the Lao PDR Sengpaseuth Rasabandith 1 1 National Agricultural Research Center, P.O. Box 811, Vientiane, Lao PDR. sengpase@laotel.com Abstract Among the three main rice ecosystems in the Lao PDR (rainfed lowland, rainfed upland, and irrigated lowland environment), the irrigated lowland ranks third in terms of area, but its production comes second after that from the rainfed lowland. In the 2000/01 dry season, the suitability of promising nonphotoperiod sensitive improved glutinous and non-glutinous varieties/lines for the irrigated lowland rice environment was evaluated at sites all over the country. The target of the National Rice Research Program was the selection of promising lines with high yield potentials in the main rice planting regions of the country (the northern, central and southern agricultural region). The varieties and lines from the shuttle breeding programs between Lao-IRRI, Thai-IRRI and IRRI Philippines were used in the evaluations and selected based on the results of the previous year. This year s dry season irrigated environment Replicated Yield Trials (RYTs) of aromatic non-glutinous lines indicated three lines (IR SRN-3-UBN-1-B-1-2, IR PMI and IR SRN-3-UBN-1-B-7-3) with high yields and good adaptation to specific locations. The days-to-maturity ranged from 113 to 129 days, which is suitable for the irrigated rice environment. These lines will be considered for release in the near future. The RYTs of 22 glutinous lines also revealed three promising lines (IR TDK-3-1-B-, IR TDK-1-2-B- and IR TDK-1-2-B- ) with yields comparable to TDK 1. Maturity ranged from 100 to 139 days which is acceptable for dry season irrigated cultivation. From the RYTs of eight promising glutinous lines, three lines (IR TDK-B-B-33-3, IR and IR B-1-1-2) were selected which achieved yields comparable to the controls TDK 1 and TDK 5 and which can be promoted to farmers in the future. The days to maturity ranged from 115 to 165 days, which is quite late for the northern provinces. The RYTs of eight promising non-glutinous lines, showed four lines (IR , IR , IR B and IR ) with good adaptation comparable to the control varieties RD 23 and CR 203. These four lines were selected for demonstration plots and testing for eating quality in the next year and might be considered for recommendation to farmers in the future. Maturity ranged from 103 to 144 days. Within the RYTs of eight released glutinous varieties, the three varieties TDK 1, TDK 3 and TDK 5 showed better adaptation than other varieties. With the average days to maturity ranging from 115 to 154 days, these glutinous varieties matured earliest in Saravane (southern region) and latest in Luang Namtha (northern region). TSN 1 matured last among these varieties. Key words: Lao PDR; rice improvement; early maturity; medium maturity; photoperiod non-sensitive; glutinous rice; non-glutinous rice; TDK 1; TDK 3; TDK 5, dry season, irrigated environment. 21

2 3 4Ì ñ ²ñÌÀ í3 4Ì3 4 öìì ê3 4ÌÃÌì1 2 øáìé 2000Œ2001 µøè ì3 4 À í3 4Ä É 3 4 À ñìº3 4¹3 4̹ìñ º 1 2Àê, ö ñ ¹ Ó 1 2Ì Ì 3 4Ì íì É 3 4À í3 4Á ÈÌÄ ÉÀÌ ÌÃ È 3 4 ì1 2 ö 3 4Ì ø À ñì¹ìñ : Ì3 4ÌÕ±öÌ, À í3 4Ä»È Áì1 2 Ì3 4 öìì ê3 4ÌÃÌ 3 4 ì1 2 ö ø À í3 4ê Áª ªÈ3 4 ñììš, 3 4Ì ø À í3 4Ì3 4 öìì ê3 4ÌÄ É Àºö3 4ÀÌœºê ºñÌ ñ 3 4 ÁªÈ öì 1 2ìò ì Á ÈÌÄ ÉÀ ñìºñì ñ º êñ Ì ø À í3 4Ì3 4±öÌ. ÁÌ ²ñÌ, 3 4 ²ñÌÀ í3 4Î1 4 Áì1 2 À í3 4 É3 4 ÒÄ Á Ä É«õ Ì Ã ÉÃÌ 3 4Ìêö ìº ì1 2 øáìé ó Ìšê 1 2Àê È ÌÃ¹È Á ÈÌ 3 4 ²ñÌê ñ ªö Ä É óê Ä É ñ Àìõº Ìêö ìº È3 4Ì 3 4, 3 4 ²ñÌÀ¹ì 3 4ÌšÄ É 3 4 ìø 1 2 ö ñ Àìõº ²3 4 ÃÌ Áì1 2 ªÈ Àê À Ì: 1 2«3 4 ñì íì É 3 4À í3 4Ì3 4Å 3 4 ³óìò òì Áì Àê Äê, À²ô ñ Àìõº ìñ À ôìä Ì3 4 öìì ê3 4Ì Â Á ÈÌÀ í3 4Ï3 4 ªíÌªð º Á Ì 3 4Ì íì É 3 4À í3 4Á¹È 3 4. ÃÌÌ Ì ñ «1 2 ö ªí̪ðÁ ÈÌ º ¹3 4ÁÌ ²ñÌê ó ñ ªö Ä É óãìà ôìä Ì3 4 öìì ê3 4Ì, ó öì 1 2ìò ø Áì1 2 ö ªö ÃÌ À ê ø À í3 4À ñìªíìªðà Ì: ²3 4 ÀÎõº, ² Áì1 2 ²3 4 êÉ. 1 2Ì Ì öì 3 4Ìêö ìº ÃÌì1 2 øáìé ÌšÄ É 1 2êɺÌùÉÀ¹ñÌ: 3 4Ìêö ìº 1 4 ê1 4 öì 1 2ìò À í3 4 É3 4 ¹º ²ñÌÄ É ó ²ñÌ IR 69502Œ-6Œ-SRNŒ-3Œ-UBNŒ-1Œ-BŒ-1Œ-2, IR Œ24Œ-PMIŒ-5Œ-7Œ-1Œ-1 Áì1 2 IR 69502Œ-6Œ-SRNŒ-3Œ-UBNŒ-1Œ- BŒ-7Œ ñ ªö Ä É ó Áì1 2 Ã¹É öì 1 2ìò ø ÃÌ 3 4 Á, º3 4 Ä É ó 3 4Ì ú1 4ÌÁ ÁªÈ 113-Œ129 ñì Á ÈÌ ó 3 4 ÀÏ ö ñ À ôìä Ì3 4 öìì ê3 4Ì Ì Ì 3 4 ²ñÌÀ¹ì 3 4ÌšÁ ÈÌ 1 2Ä ÉÁÌ1 2Ì øè 3 4 Ì3 4 Ã̺3 4Ì3 4 ö. 3 4Ìêö ìº 1 4 ê1 4 öì 1 2ìò À í3 4Î ²ñÌÄ É ó ²ñÌ IR71506-Œ27Œ-2Œ-2Œ- TDK-Œ1Œ-2Œ-BŒ-, IR 72745Œ-6Œ-TDKŒ-3Œ-1Œ-BŒ Áì1 2 IR 72738Œ-30Œ-TDK-Œ1Œ-2Œ-BŒ Ã¹É öì 1 2ìò ø ÀÏõºÌ ñì ñ TDK 1  óº3 4 ª ÁªÈ 100-Œ139 ñì ø Ä ÉÃÌÀ ôìä Ì3 4 öìì ê3 4Ì. 1 4 ê1 4 öì 1 2ìò ²ñÌÀ í3 4Î1 4 óà ÌÃÌ êö ìº, Ìêö ìº È Àìõº Ä É ²ñÌ IR 68102Œ-TDKŒ-BŒ-BŒ-33Œ-3, IR 70183Œ-74Œ-1Œ-1Œ-1 Áì1 2 IR 68835Œ-31Œ-1Œ-BŒ-1Œ-1Œ-2 Á ÈÌ Ò ó 3 4 Áª ªÈ3 4 ¹ì3 4 «É3 4ê1 4 ñ TDK 1 Áì1 2 TDK ó 3 4 ¹ ñ Ì ºº øè 3 4 Ì3 4ÃÌ óªòîé3 4. º3 4 Á ÈÌ ÉºÌ É ÃÌÁ ²3 4 ÀÎõº óº3 4 È1 4ÌÁ ÁªÈ 115Œ-165 ñì º3 4 ó öì 1 2êö 3 4 ì1 2 ñ 3 4 ø. êö ìº 1 4 ê1 4 öì 1 2ìò ²ñÌÀ í3 4 É3 4 óà Ì Â ºó Ã È öì 3 4Ì êö ìº Ì Ì Àìõº Ä É 3 4 ²ñÌ IR 70161Œ-8Œ-1Œ-1Œ-1, IR 70199Œ-1Œ-1Œ-1Œ-1, IR 68835Œ-93Œ-2Œ-BŒ-1Œ- 1Œ-1 Áì1 2 IR 70177Œ-76Œ-3Œ-1Œ-1 Á ÈÌ ñ ªö Ä û ó Ã¹É öì 1 2ìò Àê 3 4ê1 4 ñ RD 23 Áì1 2 CR 203, 3 4 ²ñÌÀ¹ì 3 4ÌšÁ È ó 3 4 ¹ ñ 1 2ºº øè 3 4 Ì3 4Ã̺3 4Ì3 4 ö ÁªÈ 1 2ªÉº Ä É ø 3 4êò Áì1 2 êö º ÌÌ1 2 ² Ì ò쪈 ºó. º3 4 Ä û ó 3 4Ì È1 4ÌÁ ÁªÈ 103-Œ144 Ìñ  1 2À² SPR 2 óº3 4 ÉºÌ É êö ìº 1 4 ê1 4 öì 1 2ìò Á ÁÌ ²ñÌÀ í3 4Î1 4 µøè 7 ÃÌê 1 2Àê, Ä É ó 3 ÁÌ ²ñÌ TDK 1, TDK 3, TDK ñ ªö Ä É ó È3 4ÁÌ ²ñ̺ˆÌê Ä Éêö ìº ÃÌ 3 4Ìêö ìº 1 4 ñìá ÈÌ óº È3 4 «É3 4ê1 4 ñ ÁÌ ²ñ̺ˆÌÅ. ñì ²ñÌ É3 4 Àêò ÌšÁ ÈÌ ó 3 4 ¹ ñ ê 1 2ÁÌ1 2Ì êñ À í3 4 É3 4 Áì1 2 À í3 4 Î1 4 ºº øè 3 4 Ì3 4Ã̺3 4Ì3 4 ö ºñÌà ÉÌš. 22

3 Introduction Of the three main rice growing environments, the rainfed lowland, the rainfed upland, and the irrigated environment, the rainfed lowland occupies the largest area, accounting for 65% of the total rice growing area with 486,800 ha in the year 2001, followed by the rainfed upland with 158,000 ha (21%) and the dryseason irrigated environment with 102,000 (14%). Total rice production has reached 2.3 million tons in 2001, with 69% of rice production coming from the rainfed lowland rice environment. Production from the upland rice environment accounts for only 12% and 19% comes from the irrigated environment. In the dry season irrigated areas photoperiod non-sensitive and mostly glutinous (ca. 85% in the 2000/01 cropping season) introduced and Lao improved varieties are planted. The most commomly planted introduced varieties are RD 10, RD 23, SPR 2 from Thailand and CR 203 from Vietnam. However, these varieties are increasingly replaced by a number of improved Lao varieties, which have been released since 1993, and which are based mainly on selections of Thai-IRRI and IRRI (Philippines) crosses. The most popular Lao varieties are TDK 1 (Tha dok kham 1), TDK 3 (Tha dok kham 3), TDK 5 (Tha dok kham 5), PNG 1 (Phone Ngam 1) and TSN 1 (Thasano 1). Although these varieties were selected mainly for wet-season cropping in the rainfed lowland environment, due to their photoperiod non-sensitivity, they have also proved to be adaptable to the dry season irrigated environment in the central and southern agricultural regions. In the north of the country, TDK 1 is the most widely grown improved variety in the irrigated environment, but it is recognized that there is a need to develop alternative varieties with better adaptability to lower temperatures, which are a major constraint during the dry season in the northern area. The broad aim of the varietal improvement program for the dry season irrigated environment (Table 1), is to provide farmers with a range of high yielding varieties of varying maturity time, although varieties, which can be harvested within days of planting, are preferred (low temperatures during the growing season in the northern agricultural region will usually extend the maturity time). The initial emphasis had been placed on producing improved glutinous varieties although improved non-glutinous genotypes are also considered. Apart from the importance of yield, other characteristics sought include resistance to brown planthopper, gall midge, stemborer, blast and bacterial leaf blight. However, as this is still an objective of breeding programs in most advanced national programs, it is unlikely that resistance to the main insect pests will become incorporated into improved Lao varieties in the immediate future. As there are limited external sources of glutinous genotypes, a crossing program was initiated in 1996 at the National Agricultural Research Center in Vientiane Municipality, aimed at providing genotypes for selection. Some glutinous genotypes have also been introduced from IRRI (Philippines), Thailand, and other countries in the region. Non-glutinous genotypes continue to be introduced from IRRI and other sources, for selection and evaluation. 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 the planting of new improved varieties such as TDK 1 and TDK 5 which are high yielding in both the rainfed lowland and irrigated environment. About 13 promising glutinous and non-glutinous lines from previous experiments with good adaptation to both rainfed lowland and irrigated environment and with high yield potentials in the on-farm trials are expected to be released in the next few years. 23

4 Materials Materials and methods Promising rice varieties and lines from the shuttle breeding program between the Lao rice research program (Lao-IRRI), Thailand, Vietnam and the Philippines, with good adaptation to the Lao conditions and some released varieties of the National Rice Research Program were used in the experiments. Inorganic chemical fertilizers 15:15:15 or 16:20:00 and 46:00:00 (NPK) were used in the experiments. Methods The experiments 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. Replication 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 m x 5 m and as RCB layouts with four replications for RYTs (2 m x 5 m). DPTs are conducted without replication and serve to compare the new varieties with well-adapted local varieties. Their plot size depends on their location but have a minimum size of 5 m x 10 m. The soils of the selected sites as well as the soil preparation methods used have to be representative of the main rice planting areas. The time of transplanting (from December to January) should be the same as 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 kg/ ha equivalent of N:P 2 O 5 :K 2 O. No pest control was undertaken during the experiments except in cases 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 / p Results and discussion Replicated Yield Trials of 20 aromatic non-glutinous lines in four provinces of the three main agricultural region of the Lao PDR The RYTs with 20 aromatic non-glutinous lines were conducted in four provinces representative of the northern, central and southern regions (Sayabouly, Vientiane Municipality, Savannakhet and Champasak). The 19 lines evaluated in this experiment were compared to the Thai improved variety RD 23 which is well adapted to the central provinces (Table 1). Compared to the control RD 23, the yields of these nineteen lines showed big differences within the four locations. Three lines (IR SRN-3-UBN-1-B-1-2, IR PMI and IR SRN-3-UBN-1-B-7-3) showed good adaptation and produced higher yields than RD 23 in some provinces. These lines were selected as promising lines for release in the future and the assessment of their eating quality will be necessary in a further study. Average yield was highest in Vientiane M. ranging from 2776 kg/ha (IR PMI- 24

5 ) to 3559 kg/ha. The highest yield was achieved by IR SRN-3-UBN-1-B-1-2 followed by IR PMI with 3506 kg/ha although both were not significantly different from the control RD 23 (3027 kg/ha). The days-to-maturity ranged from 113 to 129 days, which is suitable for the irrigated dry season environment. Average yield was lowest in Champasak ranging from 1277 kg/ha (IR SRN-1-UBN-1-B-66-3) to 2797 kg/ha (IR B-1), due to poor soil and damage by rice bug during the flowering stage which led to significant yield reduction. The days to maturity within the four experimental sites were generally shortest in Champasak (100 to 125 days) and longest in Sayabouly (127 to 145 days). The variation between early and late maturity was 2 to 3 weeks. This was the second season for this experiment, which will be concluded at the end of the next dry season 2002/03 in the irrigated environment, when the high yielding lines will be selected and planted in demonstration plots. Replicated Yield Trials of 22 glutinous lines in three provinces The RYTs of 22 glutinous lines were conducted in three provinces (Sayabouly, Vientiane Municipality and Champasak) representative of the Northern, Central and Southern agricultural regions. These glutinous lines from the shuttle breeding program between Lao-IRRI and IRRI (Philippines) had been selected at the National Agriculture Research Center (NARC) in the Lao PDR in the previous year. The high yielding Lao improved variety TDK 1 (Tha dok kham 1) was used as control. In Champasak there were only 20 lines in the experiment and in Sayabouly only 11 lines due to poor germination of some entries caused by low temperatures and rat damage during the seedling stage (Table 2). The line IR TDK-1-2-B- achieved the highest yield in both the Vientiane M. (3706 kg/ha) and the Champasak site (3488 kg/ha) yielding higher than the control TDK 1 in both provinces. Average yield was highest in Sayabouly where three of the remaining 11 lines yielded higher than the control TDK 1 with 3245 kg/ha. In Vientiane M. yields ranged widely from 1348 kg/ha (IR TDK-3-1-B- ) to 3706 kg/ha (IR TDK-1-2-B- ). The days-to-maturity ranged from 116 to 139 days, with a variation between early and late maturity of almost three weeks. In Champasak the yields ranged from 2175 kg/ha to 3488 kg/ha with IR TDK-3-3-B producing the lowest and IR TDK-1-2-B- the highest yield, followed by the control TDK 1 (3476 kg/ha). The days-to-maturity in Champasak ranged from 100 to 125 days with a variation of almost four weeks between early and late maturates. This experiment will be continued and concluded in the next dry season 2002/03, when the high yielding lines will be selected for demonstration plots and tested for eating quality. 25

6 Table 1. Grain yield and maturity of 20 aromatic non-glutinous lines tested in four provinces of the Lao PDR in the 2000/01 dry season. Variety name Vientiane Municipality Sayabouly Savannakhet Champasak Yield Maturity Yields Maturity Yields Maturity Yields Maturity kg/ha days kg/ha days kg/ha days kg/ha days IR a-d efg e a-d 125 IR a-d fg bcd cd 108 IR SRN-1-UBN-1-B d efg de d 113 IR SRN-3-UBN-1-B a a a a-d 112 IR SRN-3-UBN-1-B a-d abc ab ab 112 IR SRN-3-UBN-1-B a-d a-g ab abc 110 IR SRN-3-UBN-1-B a-d a-e abc a-d 111 IR SRN-3-UBN-1-B a-d a-f a-d bcd 113 IR SRN-3-UBN-1-B abc a-e a-d a-d 125 IR SRN-3-UBN-1-B a-d b-g abc IR SRN 2-UBN-1-B a-d d-g bcd a-d 115 IR SRN-2-UBN-1-B a-d b-g cde bcd 108 IR PMI d b-g de bcd 115 IR PMI a-d b-g abc bcd 124 IR PMI ab c-g abc IR B bcd fg a-d a 115 IR SRN-3-UBN-1-B ab ab ab bcd 115 IR SRN-3-UBN-1-B a-d b-g ab bcd 115 IR SRN-3-UBN-1-B cd a-d abc a-d 113 RD a-d g abc a-d 105 Ave cv= 10.5% cv= 14.9% cv= 11.4% cv= 24.1% LSD (5%) = 467 LSD (5%) = 587 LSD (5%) = 419 LSD (5%) = 774 LSD (1%) = 622 LSD (1%) = 782 LSD (1%) = 557 LSD (1%) =

7 Table 2. Replicated Yield Trial of 22 glutinous lines in three provinces, dry season. Variety name Vientiane Municipality Sayabouly Champasak Yields Maturity Yields Maturity Yields Maturity kg/ha days kg/ha days kg/ha days IR TDK-1-1-B d-h a-d 122 IR TDK-2-1-B e-h b-e 119 IR TDK-1-1-B c-f ab 125 IR TDK-1-2-B h a ab 119 IR TDK-3-1-B I ab 123 IR TDK-4-1-B fgh a-d 106 IR TDK-4-3-B d-h ab a-d 108 IR TDK-1-1-B e-h bc cde 104 IR TDK-1-3-B d-h ab ab 121 IR TDK-1-4-B d-h ab a-e 119 IR TDK-3-1-B bcd a de 121 IR TDK-3-3-B gh c e 104 IR TDK-1-2-B e-h cde 105 IR TDK-2-1-B h ab e 100 IR TDK-2-3-B abc ab 108 IR TDK-1-2-B a a 105 IR B-B-1-TDK-1-2-B gh IR B-6-TDK-1-1-B d-g a abc 119 IR B-B-4-TDK-1-B b-e ab ab 116 IR B-B-4-TDK-2-B 3298 ab a-d 120 IR B-2-1-TDK-1-B bcd TDK 1 (control) 2810 b-e ab ab 121 Ave cv= 13.7% cv= 9.1% cv= 11.5% LSD (5%) = 489 LSD (5%) = 451 LSD (5%) = 576 LSD (1%) = 650 LSD (1%) = 608 LSD (1%) = 771 Means followed by common letters are not significantly different at the 5% level by DMRT. Replicated Yield Trials of eight promising glutinous lines in four provinces RYTs evaluating the yields and maturities of eight promising glutinous lines were conducted in four provinces: Vientiane M, Huaphanh, Luang Namtha and Champasak. Promising lines from the shuttle breeding program between Lao-IRRI and IRRI (Philippines) that had been selected at the National Agriculture Research Center (NARC) in the previous year were screened in the experiment. The high yielding Lao improved varieties TDK 1 (Tha dok kham 1) and TDK 5 (Tha dok kham 5) were used as controls (Table 3). Yields ranged widely from 1945 kg/ha (IR ) in Champasak to 6025 kg/ ha (TDK 1) in Huaphanh (Table 3). Similarly, a big difference in the days-to-maturity was observed between the four sites ranging from 115 to 165 days. The promising glutinous lines matured earliest in Champasak and latest in Luang Namtha where the higher elevation probably delayed maturity. Within these four experimental sites there was only IR TDK-B-B-33-3, which achieved good yields comparable to the controls in all sites. Average yield was highest in Huaphanh where the lowest yield was 4073 kg/ha from (TDK B-1-B-5). At least two lines (IR and IR B-1-1-2) gave yields equal to or slightly lower than the two controls. The days-to- 27

8 maturity in Huaphanh ranged from 140 to 158 days with a variation of 2 to 3 weeks between the early and late maturates. In Champasak, where the average yield was lowest (1945 kg/ha to 3290 kg/ha) the highest yield was achieved by IR TDK-B-B-33-3, followed by the control TDK 1 (2942 kg/ha). IR and IR B both produced yields lower than 2000 kg/ha, because this site was damaged by rice bug. In Champasak, the days-to-maturity were markedly shorter than in Huaphanh ranging from 115 to 125 days. This experiment will be continued and final testing will be conducted in the next dry season 2002/03, when the high yielding lines will be selected for demonstration plots and testes for eating quality. Table 3. Grain yields and maturities of replicated yield trials of eight promising glutinous lines in four provinces Variety name Vientiane Municipality Huaphanh Luang Namtha Champasak Yields Maturity Yields Maturity Yields Maturity Yields Maturity kg/ha days kg/ha days kg/ha days kg/ha days IR b d c IR a ab c IR B ab ab abc TDK95001-B-1-B ab d abc IR TDK-44-2-B ab d ab IR TDK-B-B ab cd bc TDK 1 (control) 3338 a a a TDK 5 (control) 2447 ab bc abc Ave cv= 19.3% cv= 8.8 cv= 11.9% cv= 18.3% LSD (5%) = 801 LSD (5%) = 636 LSD (5%) = 478 LSD (5%) = 804 LSD (1%) = 1090 LSD (1%) = 866 LSD (1%) = 651 LSD (1%) = 1116 Means followed by common letters are not significantly different at the 5% level by DMRT. 28

9 Replicated Yield Trials of eight promising non glutinous lines in four provinces The yields and maturities of eight promising non glutinous lines from the International Rice Research Institute (IRRI, Philippines) were evaluated in RTYs in four provinces: Vientiane Municipality, Sayabouly, Saravane and Champasak. Two improved varieties, CR 203 from Vietnam and RD 23 from Thailand were used as controls. Yields in this experiment ranged from 1082 kg/ha (IR ) in Saravane to 3512 kg/ha (CR 203) in Vientiane M. (Table 4). The days-to-maturity ranged from 103 in Champasak to 144 days in Sayabouly where the higher elevation and low temperature delayed maturity. Three lines (IR , IR B and IR ) showed good adaptation and yields comparable to the controls RD 23 and CR 203 in all four sites. Average yield was highest in Champasak (3186 kg/ha). The lowest yield there came from IR (2910 kg/ ha) which was significantly lower than the control CR 203 but not RD 23. Four lines gave yields equal to or slightly lower than the two control varieties. The days-to-maturity ranged from 103 to 117 days and these four lines might be considered for release in the near future. In Saravane, the average yield was lowest, ranging from 1082 kg/ha (IR ) to 2006 kg/ha (RD 23). Poor soil and damage by rice bug during flowering stage were the cause of the low yields and the reason for missing maturity records of some lines. This experiment will be continued up to a final testing in the next dry season 2002/03, when the high yielding lines will be selected for demonstration plots and tested for eating quality. Table 4. Grain yields and maturities of Replicated Yield Trials of eight non glutinous promising lines in four provinces. Variety name Vientiane Municipality Sayabouly Saravane Champasak Yields Maturity Yields Maturity Yields Maturity Yields Maturity kg/ha days kg/ha days kg/ha days kg/ha days IR bc ab c c 112 IR e ab a a 105 IR de ab c bc 103 IR B bcd a a bc 111 IR ab b a a 108 SPR ab ab b c 115 CR 203 (control) 3512 a ab a ab 112 RD 23 (control) 2606 cde b a bc 117 Ave cv= 11.4% cv= 14.6% cv= 8% cv= 5.5% LSD (5%) = 481 LSD (5%) = 549 LSD (5%) = 196 LSD (5%) = 258 LSD (1%) = 655 LSD (1%) = 747 LSD (1%) = 267 LSD (1%) = 351 Replicated Yield Trials of eight released glutinous varieties in seven provinces The yields and maturities of eight released glutinous lines were evaluated in seven provinces: Vientiane, Khammouane, Luang Namtha, Saravane, Attapeu, Sekong and Champasak. These glutinous varieties from the shuttle breeding program between Lao-IRRI, IRRI (Philippines) and Thai-IRRI had been in the Lao PDR and released between the years 1993 to The Thai glutinous variety RD 10 was used as a control. Average yields ranged from 1944 kg/ha in Attapeu to 3625 kg/ha in Vientiane Province (Table 5). Average days-to-maturity ranged from 115 to 154 days. The varieties matured earliest in Saravane (Southern region) and latest in Luang Namtha (Northern region), where the higher elevation, 29

10 Table 5. Grain yields and maturities of replicated yield trial of eight released glutinous varieties in seven provinces. Variety name Luang Namtha Vientiane Prov. Khammuane Saravane Attapeu Sekong Champasak Yields Maturity Yields Maturity Yields Maturity Yields Maturity Yields Maturity Yields Maturity Yields Maturity kg/ha days kg/ha days kg/ha days kg/ha days kg/ha days kg/ha days kg/ha days TDK a a ab a a a ab 118 TDK b c b bc a a 116 TDK d c ab cd a a b 114 NTN b b ab b a a c 124 PNG bcd b a bcd a ab 115 TDK bc d ab bc a a a 112 TSN cd d d a RD 10 (control) 2966 b c ab e a Ave cv= 12.1% 5.1% 14% 6.3% 44% 21.1% 8.5% LSD (5%) = LSD (1%) =

11 lower temperature and cloudy sky delayed maturity. Yields were lowest in Attapeu where only four varieties were transplanted in the experiment due to poor germination at this site. Overall the three varieties TDK 1, TDK 3 and TDK 5 gave the achieved the highest yields over all seven sites. Conclusions The objective of the National Rice Research Program is selecting glutinous and non-glutinous, photoperiod non-sensitive varieties, which are suitable for the dry season irrigated environment. The varieties should be well adapted to irrigated environment but also with high yield potential in each of the main rice planting regions: the north, center and south of the country. The results of this dry season irrigated environment variety evaluation can be summarised as follows: The RYTs on aromatic non-glutinous lines indicated three lines (IR SRN-3-UBN-1-B-1-2, IR PMI and IR SRN-3-UBN-1-B-7-3) with good adaptation and higher yields than the control RD 23. These lines were selected as promising lines for release in the future. An assessment of their eating quality will necessary in the next study. The days-to-maturity ranged from 113 to 129 days, which suitable for irrigated rice environment. The assessment of 22 glutinous lines showed that there were three lines (IR TDK-3-1 B, IR TDK-1-2-B- and IR TDK-1-2-B- ) with yields comparable to the control TDK 1. Maturities ranged from 100 to 139 days, which is acceptable for the irrigated dry season environment. The experiment will be continued in a final testing in the next dry season 2002/03. The evaluation of yields and maturities of eight promising glutinous lines at four experimental sites indicated three lines (IR TDK-B-B-33-3, IR and IR B-1-1-2) with good adaptation comparable to TDK 1 and TDK 5 and which can be promoted to farmers in the future. The days to maturity ranged from 115 to 165 days, which is quite long for northern provinces. This experiment will be continued for a last time in the next dry season 2002/03. RYTs of eight promising non glutinous lines showed that four lines (IR , IR , IR B and IR ) were similarly well adapted to the experimental locations as the controls RD 23 and CR 203. These four lines are considered for recommendation to farmers. The days-to-maturity ranged from 103 to 144 days. This experiment will be repeated in a final evalutation in the next dry season 2002/03, when the high yielding lines will be selected for demonstration plots and tests for eating quality will be conducted. The RYTs of eight released glutinous varieties in seven sites all over the country showed that TDK 1, TDK 3 and TDK 5 achieved the highest average yields over all sites tested. The average days-tomaturity ranged from 115 to 154 days. The varieties matured earliest in Saravane (southern region) and latest in Luang Namtha (northern region) where the higher elevation and lower temperature delayed maturity. 31

12 Acknowledgements On behalf of the Rice Improvement Unit and Food Crops Section for writing the Lao-IRRI Annual Technical Report 2001, the author would like to show his gratitude to all whom it may concern, especially, the donor: the Swiss Agency for Development and Cooperation (SDC), through the Lao- IRRI Project who supported all facilities and the rice research. The assistance of the following are gratefully acknowledged: Dr. Renate Braun and Mr. Philip Gibson who gave advice, instruction and took responsibility for the English corrections. Without their help, this report would not have been finished completely. References Lao IRRI, Annual Technical Report of the National Rice Research Program and Lao-IRRI Project: Lao IRRI, Annual Technical Report of the National Rice Research Program and Lao-IRRI Project. 32