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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Keynote paper presented at the International Leucaena Conference, 1‒3 November 2018, Brisbane, Queensland, Australia.Leucaena is a dual-purpose plant suitable for producing both biofuel and feed for livestock (dairy and beef cattle, buffalo and goats). It has a high woody stem yield under repeated cutting and has a suitable chemical composition for excellent heat generation on combustion. Yields of leaf, which is a by-product of this process, are also high and the leaf has high nutritive value as an animal feed. Tarramba appears the highest yielding cultivar available, and many hybrid lines show excellent potential. Plant spacing of 1 × 0.50 m is recommended with cutting not more frequently than once a year. Harvesting of the crop should be carried out as a compromise between the needs for biofuel and livestock feed. On infertile soils application of at least 750 kg triple superphosphate, 188 kg KCl and 188 kg gypsum/ha/yr is recommended. Some limitations on growing and the management of leucaena are discussed.

Drought causes severe damage to sugarcane, reducing its product yield. Given Thailand’s weather conditions and topography, a breeding program to develop new sugarcane genotypes with a high tolerance for water stress is important to the sugarcane industry. This study created new water stress tolerant sugarcane genotypes using ethyl methanesulfonate (EMS) mutagenesis in the sugarcane cultivar Khon Kaen 3. Using 16 mM of EMS for 4 h induced callus mutagenesis (survival rate, 57.5%). The survival rates of calli treated with 10 mM of EMS for 2 and 4 h in selective media with 15% PEG were higher than that of non-EMS-treated calli. The selected calli survived and grew on selective media with 20% PEG, while non-EMS-treated calli did not grow. The mutant plantlets developed from EMS-treated calli on selective media with 20% PEG for 4 weeks had varying survival rates: 72.25% (10 mM of EMS for 2 h), 75.85% (10 mM of EMS for 4 h), and 60.61% (16 mM of EMS for 4 h). Both healthy mutant sugarcane plants (2,086) and non-mutant plants (234) were cultured on the media with 20% PEG for 16 weeks. Of these, 462 mutant sugarcane plantlets survived and developed on the media, but all the non-mutant sugarcane plantlets died during the selection process. Mutagenesis induced using treatment 4 produced the highest frequency of mutant sugarcane plantlets with water-stress tolerance (45.5%). In total, 136 selected mutant sugarcane plants were transplanted to a greenhouse for evaluation under managed water stress. Fourteen mutant sugarcane plants stayed green after the third cycle of water stress, but the KK3 sugarcane cultivar showed damage on 50% of the leaves. Thus, EMS mutagenesis and evaluation using in vitro and greenhouse methods were successful in developing new sugarcane clones with high water-stress tolerance, which is important for sugarcane breeding programs.

The recent increase in dairy and cattle production in Thailand has increased demand for high-quality roughage, particularly corn silage. Although there has been a great deal of research on field corn, far fewer studies have focused on corn intended as silage. This study involved a field experiment that analyzed crop management methods, focusing on plant spacing and 8 of the field corn varieties most commonly used in Thailand. The objectives were to determine which plant spacing and variety produced the best forage yield and silage qualities of corn silage. The plantings were arranged in a split-plot Randomized Complete Block Design (RCBD) with four replications. The main plot contained two spacing (75×20 and 75×25 cm2), each with subplots of 8 field corn varieties (SW5, NS2, NS3, NSX982013, TE1719, WS6437, WS6440, WS6442). All plants received the same crop management care regarding soil conditions, water, fertilization, and weeding. The results showed plant spacing did not significantly affect plant height (cm) and ears per plant, but the narrower 75×20 cm2 spacing produced the highest fresh leaf yield (13 t ha-1) and dry stalk yield (4.5 t ha-1) (p < 0.05). At 75×20 cm2 spacing, the TE1719 varietal had more ears per plant than SW5 (the check variety). TE1719 had the best fresh ear, stalk, and total biomass yield at both spacing of all the varieties. With regard to silage quality, the plant spacing did not significantly affect the CP, ADF, ADL, ash, and pH of the corn silage. The study revealed planting TE1719 varieties at 75×20 cm2 spacing is more economical for farmers because it increases forage yields without negatively affecting the nutritional value of corn silage.