Author : Vua Xiongsiyee

Summary : Luang Prabang Province is recognized as a major area of diversity of Oryza sativa L. in Lao PDR. Grain morphology can be used as the preliminary information of genetic variation among different rice varieties in the local germplasm, which can be a source of value added traits for rice breeding program. Nutritional qualities were also studied to improve high nutritive rice varieties to solve the problem of malnutrition among rice consumers, especially in Lao PDR where nutrient deficiency is a serious problem among the population. The purpose of this study was to evaluate the variation in grain morphology and nutritional qualities of local rice varieties from Luang Prabang Province, Lao PDR.

A total of 60 samples within 49 varieties were collected from three districts, Phonxay (PX), Pak Ou (PO), and Xieng Ngeun (XNg), with two villages each. The samples were separated into 26, 10, and 24 samples from PX, PO, and XNg, respectively and among these samples, 42 and 18 samples were glutinous and non-glutinous endosperm types, respectively. The non-pigmented pericarp color was found in 51 samples, four in red, and five in black. The number of samples collected from each village varied from four to 14 samples, which was distinguished into one to five varieties in each household.

Grain size among 60 rice samples, grain length, width, and thickness ranged from 8.61 to 11.63, 2.66 to 4.27, and 1.97 to 2.47 mm, respectively. Grain shape was determined by using the ratio of grain length to width and almost all samples
(58) were distinguished as large grain type and the rest in slender type. One hundred grain weight among 60 rice samples were also varied from 2.54 to 4.57 g and 2.05 to
4.04 g among paddy rice and brown rice, respectively. Moreover, grain weight was varied with grain length, width, and thickness in multiple regression of y = 0.39 (grain length) +0.53 (grain width) +1.42 (grain thickness) -5.52 at R2 = 0.89 (p < .05). Even though most samples were classified as large grain shape, this study has demonstrated the variation in grain morphological characteristics of upland rice varieties from Luang Prabang Province, Lao PDR.

Nutritional characteristics measured in the collected samples as brown rice ranged from 7.42 to 11.15 percent protein, 0.02 to 0.19 g Si/100 g, 3.96 to 45.41
mg Fe/kg, 15.23 to 24.16 mg Zn/kg, 0 to 2.23 percent anthocyanin, and 0.52 to 4.35 percent antioxidant capacity. The highest nutrient concentration was found as follows: protein concentration was found in KMD and CKH varieties from CC village and KKA from PT village; silicon was found in KMD and CDA varieties at CC village; Fe was found in NPP at PT village; Zn was found in LY at PSN village, anthocyanin was found in KMD at CC village; and antioxidant capacity was found in KMD at CC village and NMD at PSN village. The samples in glutinous endosperm type were found with very low amylose content and non-glutinous endosperm types with low amylose content. Both amylose content and alkaline spreading value tested indicating the preference of soft texture in cooked rice among the population in the study areas. Cluster classification was scattered into four major groups that contributed 69.49 percent of total variation. Group I was classified based on husk color, brown rice weight, paddy weight, width, and thickness and most of samples in this group were from HM at altitude of 1,013 m from mean sea level. Group II was based on amylose content and alkaline spreading with most of samples from Chomchieng and Hoi-Oth villages at altitude of 1,204 m and 816 m, respectively. Group III was based on grain shape with most of samples from Phasanine Village at altitude of 1,479 m. Group IV was based on zinc, protein, iron, and silicon contents.

In conclusion, this research has showed that the local rice germplasm kept and used by farmers in Luang Prabang was mostly in a large grain shape, non-pigmented pericarp color, and glutinous endosperm type, which was varied in nutritional qualities among the samples. The variety with high nutritional value can be used as source of genetic material in breeding program for high nutrient rice as found in this germplasm. However, the interaction effect between variety and environmental condition controlling grain nutritional value should be carefully considered when dealing with the material selection. Therefore, the cooperation between the institute of rice research centers and other related departments is needed in terms of breeding, financial support, and convenience in providing improved varieties of rice with high nutrients to solve the problem of malnutrition and micronutrients deficiency among the populations of Lao PDR in the future.