Data base establishment of rice breeding program in Laos

One of the national research priorities is to improve the efficiency of the current breeding and variety testing program in order to accelerate the introduction of better varieties for farmer’s adoption. The database for the rice breeding is the key to achieve the breeding program and would provide valuable scientific information to improve the efficiency of the breeding program for target environments. The objectives of this database were to collect, document and utilize the available data from the national rice breeding program in Laos. Rice breeding program was established at Rice and Cash Crop Research Center in 1991, in collabolation with IRRI, and supported of funding by the government of Switzerland. From 1991 to Philippines and from Thai-IRRI program. Out of 1.627 lines of F2 population, 4 lines were released as TDK and PNG varieties. Out of 64 imported promising lines, 13 lines were released as TDK, TSN, PNG and NTN varieties for different agro climatic zones in Lao PDR. Hybridization at RCCRC was started in 1994, since than, about 272 crosses were made by the Lao breeders. Out of 272 crosses made, so far 8 clones were released as TDK and TSN vareieties and 34 lines were identified as promising lines. Among all parents used in the crossing program at RCCRC, TDK 1 was the dominant parent for evolving promising lines for Lao PDR

Evaluating the Performance of Rice Genotypes for Improving Yield and Adaptability Under Direct Seeded Aerobic Cultivation Conditions

With the changing climatic conditions and reducing labor-water availability, the potential contribution of aerobic rice varieties and cultivation system to develop a sustainable rice based agri-food system has never been more important than today. Keeping in mind the goal of identifying high-yielding aerobic rice varieties for wider adaptation, a set of aerobic rice breeding lines were developed and evaluated for grain yield, plant height, and days to 50% flowering in 23 experiments conducted across different location in Philippines, India, Bangladesh, Nepal, and Lao-PDR between 2014 and 2017 in both wet and dry seasons. The heritability for grain yield ranged from 0.52 to 0.90. The season-wise two-stage analysis indicated significant genotype x location interaction for yield under aerobic conditions in both wet and dry seasons. The genotype × season × location interaction for yield was non-significant in both seasons indicating that across seasons the genotypes at each location did not show variability in the grain yield performance. Mean grain yield of the studied genotypes across different locations/seasons ranged from 2,085 to 6,433 Kg ha−1. The best-fit model for yield stability with low AIC value (542.6) was AMMI(1) model. The identified stable genotypes; IR 92521-143-2-2-1, IR 97048-10-1-1-3, IR 91326-7-13-1-1, IR 91326-20-2-1-4, and IR 91328-43-6-2-1 may serve as novel breeding material for varietal development under aerobic system of rice cultivation. High yield and stable performance of promising breeding lines may be due to presence of the earlier identified QTLs including grain yield under drought, grain yield under aerobic conditions, nutrient uptake, anaerobic germination, adaptability under direct seeded conditions, and tolerance to biotic stress resistance such as qDTY2.1, qDTY3.1, qDTY12.1, qNR5.1, AG9.1, qEVV9.1, qRHD1.1, qRHD5.1, qRHD8.1qEMM1.1, qGY6.1, BPH3, BPH17, GM4, xa4, Xa21, Pita, and Pita2. The frequency of xa4 gene was highest followed by qAG9.1, GM4, qDTY3.1, qDTY2.1, qGY6.1, and qDTY12.1

Crop Performance and Water Productivity of Transplanted Rice as Affected by Seedling Age and Seedling Density under Alternate Wetting and Drying Conditions in Lao PDR

Drought is common under rainfed lowlands in Lao People’s Democratic Republic, and with the uncertain onset of rains during the wet season, delay in transplanting results in yield reduction. This study aims to explore ways to ameliorate the negative influence of delayed transplanting on rice crop. A field experiment was conducted for two wet seasons to investigate the effect of seedling age and seedling density on crop performance in terms of grain yield and water productivity. The experiment was laid out in a split–split plot design in four replicates, with seedling age as the main plot, seedling density as the subplot, and varieties as the sub-sub plot. In both years, there were significant seedling age and variety interactions on grain yield. Higher grain yields were observed with older seedlings having stronger tillering propensity. Seedling density did not affect grain yields in both years, but on grain yield components. Shorter duration variety received less supplemental irrigation than longer duration varieties. Late transplanting improved total water productivity but decreased irrigation water productivity due to harvesting delay. The total crop growth duration (from sowing to maturity) was prolonged with transplanting delay. However, the total stay of plants in the main field (from transplanting to maturity) was reduced by 3–5 d for every 10 d delay in transplanting. The results indicated that a good selection of varieties and increasing seedling density improve crop performance and water productivity with delayed transplanting

Combine harvesting efficiency as affected by rice field size and other factors and its implication for adoption of combine contracting service

Small combine harvesters have become popular in SE Asia recently, but small rice fields appear to limit its field operation and hence its wide adoption by smallholders. Combine harvesting efficiency, the area of paddy field harvested per unit time, was determined for 6 seasons in Central Lao PDR for over 400 fields varying in size and toposequence position, rice varieties grown, crop establishment methods and crop conditions particularly lodging at harvest. Combine harvesting efficiency was commonly about 3\ua0ha/day in small fields of less than 1000\ua0m and increased with the increase in field size up to 5\ua0ha/day in the size of about 2000–3000\ua0m, but not beyond this range. Lower efficiency was also found in wet season than dry season, and also crops established from broadcasting compared with transplanting and drill seeding, at least partly because broadcasted crops tended to lodge more often than crops established from other methods. Photoperiod sensitive, long duration varieties grown in lower field positions also tended to have lower combine efficiency. Using the data obtained in this work, net return of combine adoption to farmers was estimated for different combine charge fees and yield levels. Increasing combine harvesting efficiency by 50% with increased field size would increase the net income of combine harvesting contractors by around 50% at current charges, allowing them to reduce the combine harvesting fees they charge. This would aid the adoption of combine harvesting services

Research strategies for mechanised production of rice in transition from subsistence to commercial agriculture: a case study from Khammouan in Lao PDR

Mechanised rice production has started to take place in response to rural labour shortage and increased labour cost in Khammouan province in central Laos where subsistence rice production is being replaced with commercial agriculture. This paper summarizes the results of recent findings of four mechanised items, combine harvester, seed drill, transplanter, and artificial grain dryer, and discusses research strategies for advancement of the mechanised rice production system. Combine and seed drill were considered to have good potential for reduction in production cost and hence the likelihood of farmer adoption. Synergistic effects of these four and other items are noted; for example, the adoption of combine harvesting service is associated with farmer’s accessibility to drying facilities. Artificially dried grain has been shown to decrease broken rice component during the milling process, resulting in higher grain quality, and hence increased marketability. The proposed research strategies focus on the production of rice with reduced cost and increased grain quality for increased farmer adoption of contracting services available for mechanised rice production. The strategies include promotion of large size paddy fields to allow efficient use of machinery and reduced service fees. Other strategies which are discussed include identification of suitable rice varieties and other technologies that maximize in field machinery efficiency. The requirements of actors in the rice value chain working together for mechanised rice production are emphasised

Rice milling quality as affected by drying method and harvesting time during ripening in wet and dry seasons

Head rice recovery is known to decrease with the delay in harvesting during ripening, but this effect may differ between wet season (WS) and dry season (DS) and among different paddy drying methods. In five experiments, rice was harvested by hand between 25 and 45\ua0days after flowering in DS and WS when temperature around harvest was slightly above and below 30°C, respectively. The highest head rice recovery was generally obtained when rice was harvested at 25\ua0days after 75% flowering. Delaying harvest to 30\ua0days resulted in significant reduction in head rice recovery in 3 out of 7 cases and further delay to 35\ua0days resulted in significant reduction in 8 out of 10 cases. For the crops harvested 25\ua0days after flowering and dried with a flatbed dryer head rice recovery improved compared to sun drying in two experiments. When harvesting was delayed, sun drying tended to reduce head rice recovery compared to artificial drying. Sun drying only in the morning also improved head rice recovery compared to drying for the whole day. For a given drying method, head rice recovery decreased with increase in heat sum from flowering to harvest. It is concluded that rice crops should be harvested in both DS and WS around 25\ua0days after 75% flowering when heat sum with base temperature of 10°C was around 450–500 degree-days. If an artificial dryer is not available, rough rice should be sun dried only in the morning with frequent stirring and mixing to promote more even drying. Abbreviations: WS: wet season; DS: dry season

A diagnostic on-farm survey of the potential of seed drill and transplanter for mechanised rice establishment in Central Laos and Southern Cambodia

Due to labour shortages in rural areas, traditional manual transplanting is often no longer feasible and alternative rice establishment methods are required in Central Laos and Southern Cambodia. The work reported here evaluated the potential of a seed drill and transplanter by comparing yield of over 200 crops established by different methods including broadcasting in farmer’s fields under their management in 3 seasons in Laos. In Cambodia, yield of rice established by drill planting was compared with farmers’ practice by broadcasting in two early wet seasons. When mechanised and manual establishment methods were compared in each of 10 farms in the same season in Laos, drilled crops produced slightly higher yield compared with manual planting. Similarly in Cambodia, the technology package including drill produced slightly higher yield and higher gross margin despite lower plant density than that of the farmer practice based on broadcasting. On the other hand, mean yield established using drill was 26% lower than manually transplanted crops across all seasons and villages in Laos, indicating that possibly drills were used in fields unsuitable to them. Mean yield established using transplanter across all fields was 16% lower than manually transplanted crops. Hill density of crops established from transplanter was lower than that from manual transplanting, and yield increased with increased hill density. The labour requirement and hence establishment cost were greatly reduced compared to manual transplanting. The results show the economic advantage of mechanised rice establishment particularly of seed drills. Abbreviations: WS: wet season; DS: dry season