Eight cultivars of napiergrass (Pennisetum purpureum Schumach.), namely Dwarf, Muaklek, Bana, Taiwan A148, Common, Wruk wona, Tifton and Kampheng San, were grown in central Thailand in [2008][2009] and biomass yield, chemical composition and theoretical ethanol yield were measured. Harvests were made every 3 months. Biomass yield and cell wall compositions differed significantly (P < 0.05) among cultivars. Tifton produced the highest annual biomass yield at 58.3 t/ha followed by Wruk wona (52.1 t/ha), while the lowest yield of 27.1 t/ha was in Dwarf. Biomass yield varied with season with highest yields in May and lowest in February during the dry season. Cell wall concentrations were higher in the tall cultivars than in the short ones (Dwarf and Muaklek) (P < 0.05). Theoretical ethanol conversion efficiency ranged from 350 to 460 L/t DM among the cultivars following pretreatment with steam explosion. While a number of cultivars showed significant potential for use as biofuels in central Thailand, Tifton seemed to be the most promising.

The effects of inter‐cutting interval on biomass yield, growth components and chemical composition of napiergrass (Pennisetum purpureum Schumach) as a source of bioenergy was investigated over 1 year in Thailand. Five cutting intervals (1‐, 2‐, 3‐, 6‐ and 12‐monthly) were examined on three napiergrass cultivars (Bana [hybrid with pearl millet], Common [normal type] and Muaklek [dwarf type]). Peak biomass yield occurred in all cultivars with 3‐month inter‐cutting interval, with a mean of 50.2 t dry matter (DM) ha−1 year−1 averaged across cultivars, while a 6‐month interval produced 46.2 t DM ha−1 year−1. Although cellulose concentration increased as inter‐cutting interval increased, energy concentration in the harvested material also peaked with 3‐monthly cutting. Both Common and Bana were superior to Muaklek in terms of DM production. Further studies are needed to refine harvesting frequency in different seasons to maximize biomass yields while ensuring cash flow and minimizing harvesting costs.

This study was designed to investigate differences in patterns of physiological responses to salinity stress among five japonica rice cultivars in comparison with FL478 as a salinity tolerance check. Five japonica cultivars were screened for salinity tolerance at seedling stage based on visual symptoms of salt injury index and physiological parameters including dry matter production, electrolyte leakage ratio and ion concentration. The results indicated that cultivars Ouukan383 and FL478 were relatively more salinity tolerant than other cultivars and that Kanniho was the most salinity‐sensitive cultivar. Ouukan383 showed higher leaf water content and lower electrolyte leakage ratio under salinity stress. Notably, under salinity stress, Na+ concentration in the leaf blades was much lower in Ouukan383 than in FL478, but was much higher in Kanniho. To understand the basis for these differences, we studied transcript levels of the genes encoding Na+ transport proteins in different tissues. In response to salinity stress, Ouukan383 had highly induced expression of the OsHKT1;4 gene in the leaf sheaths, corresponding to higher Na+ accumulation in the leaf sheaths and lower Na+ accumulation in the leaf blades. On the other hand, the sensitive cultivar, Kanniho, had highly induced expression of the OsSOS1 and OsNHX1 genes in the leaf blades, whose gene products are responsible for Na+ efflux outside cells and Na+ compartmentalization into vacuoles. Thus, the salinity‐tolerant and salinity‐sensitive cultivars differed in their responses to Na+ fluxes in plant cells using different transport systems in each tissue type. The salinity‐tolerant japonica cultivar, Ouukan383, has an effective Na+ exclusion mechanism at the leaf sheaths to prevent Na+ accumulation in the leaf blades. Such a mechanism, in combination with other genetic traits (e.g. Na+ exclusion at the roots mediated by OsHKT1;5), offers the potential to improve salinity tolerance in rice.

The present study was conducted to determine the effect of spacing on the growth, biomass production and wood quality of leucaena in order to be used as a fuel crop. Leucaena was grown in a field experiment at the Suwanvajokkasikit Research Station, Pak Chong, Nakhon Ratchasima, Thailand in 2006-2010. The experiment was arranged in a randomized complete block design with 4 replications. The treatment consisted of six spacings (1 × 0.25, 1 × 0.5, 1 × 1, 1 × 1.5, 2 × 0.5 and 2 × 1 m). The results showed that spacing had a significant effect on plant height, diameter at breast height, the number of coppice stumps and biomass yield. Wider spacings resulted in greater plant height. The widest spacing (2 × 1 m) exhibited the higher stem diameter and sprout number than the narrow spacing. The narrowest spacing of 1 × 0.25 m spacing produced the highest total dry weight of leaf, woody stem and biomass yield. The spacing did not have an influence on the heating value and the content of H, N, S, Mg, Cl and ash. However, some of the chemical compositions show significant different with different spacings such as C, O, P, K and Ca content.

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