A. Patanothai

Seasonal variation in the dynamic growth and development traits of peanut lines

Physiological traits responsible for differences in yield performance among pre-released genotypes are normally not known. The objective of the present study was to evaluate seasonal variations in dynamic growth and development traits between 12 large-seeded Virginia-type and 14 small-seeded Spanish-type advanced breeding lines of peanut ( Arachis hypogaea L.). The experiment was conducted in 1999 and 2000 at Khon Kaen University in Northeast Thailand for three planting dates, representing the early-rainy season, mid-rainy season and dry season. Very similar phenological development was observed for all lines within each group and between the early and the mid-rainy seasons. However, a lower temperature during the early growth stage in the dry season delayed flower initiation and extended maturity. During this period, crop growth rates as well as the development rate for leaf area index and specific leaf area were also lower compared with the rainy seasons. On average, both pod yield and total biomass for the rainy season and the dry season were about the same. Variations among lines within each group were also small. For these advanced breeding lines, the pod growth rate was the most important yield determinant while the crop growth rate had lesser effect and the partitioning coefficient and pod-filling duration had no significant effect. However, the crop growth rate, pod growth rate and partitioning coefficient were important traits for a line to be the top yielder. Pod-filling duration was also important when the lines involved were considerably diverse in maturity and seed size. Information on these traits, if used together with final pod yield, will make varietal selection more efficient.

Land-Use Sustainability of Composite Swiddening in the Uplands of Northern Vietnam: Nutrient Balances of Swidden Fields during the Cropping Period and Changes of Soil Nutrients over the Swidden Cycle

This study examined the sustainability of the swidden component of the composite swiddening system practiced by the Tay ethnic minority in Tat hamlet, Hoa Binh province in Northern Vietnam. This farming system is thought to be suitable for the uplands where land degradation is a serious problem. The common swidden rotation of two years of rice, two years of cassava and five years of bush-tall grass fallow was evaluated for the extent of land degradation during the cropping period by nutrient balance analysis, and for soil nutrient status throughout the swidden cycle through soil analysis. Four fields representing the individual years of cropping and three fields representing the first, the third and the fifth years of bush-tall grass fallow were selected for field measurements. Nutrient balance analysis indicated substantial losses of all major nutrients, particularly K, in all cropping years. Soil analysis also showed a decline in soil fertility during the cropping period and a partial restoration of soil fertility during the fallow period. However, only five years of bush-tall grass fallow was not sufficient to restore the original level of soil fertility. Thus, swidden fields in Tat hamlet are degrading, posing a serious threat to their land-use sustainability.

Extractions of High Quality RNA from the Seeds of Jerusalem Artichoke and Other Plant Species with High Levels of Starch and Lipid

Jerusalem artichoke (Helianthus tuberosus L.) is an important tuber crop. However, Jerusalem artichoke seeds contain high levels of starch and lipid, making the extraction of high-quality RNA extremely difficult and the gene expression analysis challenging. This study was aimed to improve existing methods for extracting total RNA from Jerusalem artichoke dry seeds and to assess the applicability of the improved method in other plant species. Five RNA extraction methods were evaluated on Jerusalem artichoke seeds and two were modified. One modified method with the significant improvement was applied to assay seeds of diverse Jerusalem artichoke accessions, sunflower, rice, maize, peanut and marigold. The effectiveness of the improved method to extract total RNA from seeds was assessed using qPCR analysis of four selected genes. The improved method of Ma and Yang (2011) yielded a maximum RNA solubility and removed most interfering substances. The improved protocol generated 29 to 41 µg RNA/30 mg fresh weight. An A260/A280 ratio of 1.79 to 2.22 showed their RNA purity. Extracted RNA was effective for downstream applications such as first-stranded cDNA synthesis, cDNA cloning and qPCR. The improved method was also effective to extract total RNA from seeds of sunflower, rice, maize and peanut that are rich in polyphenols, lipids and polysaccharides.

Genotypic variation of resistance to southern stem rot of Jerusalem artichoke caused by Sclerotium rolfsii

Southern stem rot caused by Sclerotium rolfsii is a significant problem of Jerusalem artichoke (Helianthus tuberosus L.) production in Thailand. Resistant varieties are not available. The objective of this study was to investigate genetic variability of Jerusalem artichoke genotypes for resistance to stem rot caused by S. rolfsii. Ninety-one Jerusalem artichoke genotypes were evaluated under greenhouse conditions. Traits evaluated included disease score, lesion length, days to permanent wilting, plant height, shoot dry weight, and root dry weight index. Number of days from inoculation until permanent wilting was the only trait with statistically significant differences among genotypes. Based on this trait, genotypes were categorized into two distinct groups: resistant and susceptible. Genotypes that consistently expressed relative resistance to S. rolfsii included HEL 280, HEL 278, HEL 293 and JA 98. These genotypes may be useful to plant breeders as sources of germplasm for incorporating resistance to S. rolfsii into Jerusalem artichoke.

Seasonal responses and genotype-by-season interactions for the growth dynamic and development traits of peanut

Information on the interactions between genotypes and environments for physiological traits of peanut (Arachis hypogaea L.) is limited. The objective of the present study was to evaluate the effects of seasons and genotype x season (G x S) interactions for dynamic growth and development traits of peanut. Fifteen peanut lines varying in maturity duration, seed type and yield level were grown in a field experiment at the Khon Kaen University in Northeast Thailand during the 2002 and 2003 rainy seasons and the 2003 and 2004 dry seasons. Data were recorded on phenological development stages, pod yield and final biomass, and leaf area index (LAI), crop growth rate (CGR), pod growth rate (PGR), partitioning coefficient (PC), pod harvest index (HI), shelling percentage, and specific leaf area (SLA) were determined. Seasonal effects were found for all development and growth traits of the test peanut lines. Crop duration for the dry season was much longer than for the rainy season because of low temperatures during the early growth stage, causing a delay in flowering and a longer period of pod formation. The test peanut lines showed small differences in the duration of vegetative development and pod formation, but varied greatly in the seed filling duration. This period also showed the greatest differential responses to seasons between the peanut genotypes. Crop yields for the 2003 rainy and the 2004 dry seasons were much lower than for the other two seasons because of late leaf spot disease in the 2003 rainy season and cool temperatures at flowering in the 2004 dry season, resulting in poor pod setting, low PGR and low HI. The test peanut lines differed considerably in pod and biomass yields and all the growth traits measured. Significant G x S interactions were also found for all of these traits, though were much smaller than season effect. Regression analyses identified PGR as the dominant physiological trait determining the G x S interaction for pod yield. Exploring marker-assisted selection for this trait is suggested.

Effect of end of season water deficit on phenolic compounds in peanut genotypes with different levels of resistance to drought

Terminal drought reduces pod yield and affected the phenolic content of leaves, stems and seed of peanut (Arachis hypogaea L.). The aim of this study was to investigate the effects of end of season water deficit on phenolic content in drought tolerant and sensitive genotypes of peanuts. Five peanut genotypes were planted under two water regimes, field capacity and 1/3 available water. Phenolic content was analyzed in seeds, leaves, and stems. The results revealed that terminal drought decreased phenolic content in seeds of both tolerant and sensitive genotypes. Phenolic content in leaves and stems increased under terminal drought stress in both years. This study provides basic information on changes in phenolic content in several parts of peanut plants when subjected to drought stress. Future studies to define the effect of terminal drought stress on specific phenolic compounds and antioxidant properties in peanut are warranted.

Cytotoxic effects of peanut phenolics possessing histone deacetylase inhibitory activity in breast and cervical cancer cell lines

BACKGROUND Epigenetic histone modifications are considered as a promising avenue for cancer preventive and therapeutic strategies. The purpose of this study was to evaluate the antiproliferative and histone deacetylase (HDAC) inhibitory activity of selected peanut phenolics, including p-coumaric acid, ferulic acid, sinapinic acid and resveratrol, in MCF-7 and HeLa cells. METHODS The cytotoxic and HDAC inhibitory activities were assessed by MTT assays, flow cytometric analyses of cell cycle arrest and apoptosis induction, and western blotting. RESULTS The results showed that all four phenolics inhibited proliferation of both MCF-7 and HeLa cells in a dose-dependent manner. Among the phenolics tested, resveratrol was the most effective in inhibiting growth of cancer cells. Treatment with all phenolics resulted in histone H3 hyperacetylation in both cell lines, indicating potential for HDAC inhibition. These phenolics induced apoptosis in both MCF-7 and HeLa cells in a concentration-dependent manner. Moreover, all phenolics induced G0/G1-phase arrest of the cell cycle in MCF-7 cells while p-coumaric and ferulic acids caused S-phase arrest in HeLa cells. Exposure to p-coumaric acid increased p53 and p21 expression but decreased CDK4 levels in both cell types, which could result in the observed G0/G1 arrest. Moreover, inhibition of ERK1/2 phosphorylation by ferulic acid and resveratrol contributed to cell growth inhibition. CONCLUSION Peanut phenolics appear to influence the extent of histone acetylation in MCF-7 and HeLa cells, and this activity modulates multiple pathways that are implicated in cancer prevention.

CSM-CERES-Rice model to determine management strategies for lowland rice production

The cropping system model, namely, the crop environment resource synthesis-rice (CSM-CERES-Rice) model, is a decision supporting tool for the design of crop management. This study aimed to determine management practices for increasing rice (Oryza sativa L.) production in Laos by using the CSM-CERES-Rice model. The model was evaluated with data sets from the TDK8 and TDK11 cultivars in farmers’ fields in the Vientiane plain in 2012. Anthesis and harvesting dates, growth and yield for various management scenario combinations (eight transplanting dates × two levels of plant densities × three rates of nitrogen (N) fertilizer application) for both cultivars were simulated by the model from 1980 to 2012. The model evaluation results showed strong agreement between simulated and observed data for days to harvest with a difference within four days. The model provided acceptable accuracy for grain yields with normalized root mean square error values ranging between 1 and 16 %. The results from the model application indicated that TDK8 and TDK11 produced similar yields. Transplanting TDK8 with two plant densities produced similar yields. The highest yield for both cultivars was achieved on the transplanting date of 15 Jan. N-fertilizer application at 60 and 120 kg N ha−1 was able to increase yield for TDK8 by 50 and 87 %, respectively, and for TDK11 by 54 and 70 %, respectively. Rice transplanted on 15 Jan with 5 seedlings hill−1 and N-fertilizer at 120 kg N ha−1 had the highest average yield for both cultivars with 6,460 and 6,351 kg ha−1 for TDK8 and TDK11, respectively. The CSM-CERES-Rice model is an alternative tool in determining crop management practices for rice production.

Types of gene effects governing the inheritance of oleic and linoleic acids in peanut ( Arachis hypogaea L.)

Oleic and linoleic acids are major fatty acids in peanut determining the quality and shelf-life of peanut products. A better understanding on the inheritance of these characters is an important for high-oleic breeding programs. The objective of this research was to determine the gene actions for oleic acid, linoleic acid, the ratio of oleic to linoleic acids (O/L ratio) and percentage oil (% oil) in peanut. Georgia-02C, SunOleic 97R (high-oleic genotypes) and KKU 1 (low-oleic genotypes) were used as parents to generate P 1 , P 2 , F 2 , F 3 , BC 11 S and BC 12 S. The entries were planted in a randomized complete block design with four replications in the rainy season (2008) and the dry season (2008/2009). Gas liquid chromatography (GLC) was used to analyze fatty acid compositions. The data were used in generation means analysis to understand gene effects. The differences in season, generation and generation X season interactions were significant for oleic acid in the crosses Georgia-02C X KKU 1 and SunOleic 97R X KKU 1. Additive, dominance and epistasis gene effects were significant for oleic acid, linoleic acid, O/L ratio and % oil. Initial selection can be carried out in early segregating population, and final selection in late generations. Keywords: Breeding, gene actions, generation mean analysis, groundnut, oil quality

Evaluation of Groundnut Stover Management Strategies in a Legume-Rice Rotation

ABSTRACT Groundnuts grown after rice often lead to a gap of 1–3 months between legume harvest and planting of the next rice crop in many parts of Southeast Asia. To identify the best stover management strategy in such systems, the effect of methods of application (surface application vs incorporation), complementary mineral (NPK) additions and time of incorporation of groundnut stover on growth of rice KDML 105 and on decomposition (litter bag) was assessed. Groundnut provided 7500 kg ha−1 of stover corresponding to a recycling of 100 kg N ha−1, 10 kg P ha−1 and 74 kg K ha−1 which resulted in higher seed yield of the succeeding rice compared with removing stover from the field. Initially, low leaf area index where stover was incorporated 6 and 13 days before transplanting indicated a negative effect of decomposing stover; however, rice plants fully recovered subsequently. N application at panicle initiation did not have a significant effect on dry matter yields, although it increased seed N contents, especially those of the early stover application treatments. Neither N application nor omission of PK fertilizer at rice transplanting had any significant effect on rice growth suggesting groundnut stover is an effective basal fertilizer. N accumulation in rice increased with decreasing time of stover application before rice transplanting probably associated with rapid N (and K) release from residues. Storage of residues and application shortly before rice transplanting led to a better recycling of N but the associated seed yield gains were small and probably not sufficient to make it an attractive alternative for farmers.