Seven sunflower (Helianthus annuus L.) inbred lines were crossed in 77 half diallel to obtain 21 F 1 hybrids. These lines were used to estimate general combining ability (GCA) and specific combining ability (SCA) effects for yield, head diameter, 1,000-seed weight, plant height and oil content in order to select suitable parents for hybridization and to identify the promising hybrids. The 7 inbred lines and 21 hybrids were planted in a randomized complete block design with three replications at Nakhon Ratchasima, Thailand during 2008-2009. General combining ability and specific combining ability were estimated for seed yield, head diameter, 1,000-seed weight, plant height and oil content. The results revealed that mean squares for GCA were highly significant for head diameter and significant for yield and oil content. Mean squares for SCA were highly significant for 1,000-seed weight and plant height, while those of yield, head diameter and oil content were non-significant. Components of variance showed that the GCA variance was higher than the SCA variance for yield, head diameter and oil content. These results indicated that additive gene action was more important than non-additive gene action for these traits. Inbred line 5A exhibited the highest GCA effects for yield and oil content, followed by the line 2A. Among all the crosses, 5A2A showed the greatest positive SCA effects for 1,000-seed weight and oil content. Thus, the two inbred lines (2A and 5A) revealed good potential to be used as parents for hybrid.

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The aims of this research were to investigate the effects of soil moisture on cassava growth and physiological processes and to determine the critical soil moisture contents. To fulifll the research objectives, cassava was grown under five levels of soil moisture, including 50, 40, 30 and 20% of soil available water holding capacity (AWHC) along with control (no irrigation). Physiological traits and plant growth parameters were measured. The results showed that cassava grown under 50% of AWHC exhibited the highest photosynthesis rate, stomatal conductance, predawn leaf water potential and chlorophyll activity. All physiological traits decreased significantly when the moisture content was less than 40 and 20% of AWHC in sandy clay loam and loamy sand soil, respectively. Predawn leaf water potential was used to determine the critical point of soil moisture. It was found that the critical soil moisture contents were 39.0 and 15.7% of AWHC in sandy clay loam and loamy sand soil, respectively.

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Globba (Zingiberaceae) are attractive herbaceous plants widely used as ornamental plants. However, cultivation is limited because of low propagation rate and depends on the season only. This research aimed to compare growth and physiological responses of Globba schomburgkii Hook. f. and Globba marantina L. under both soil and hydroponic conditions. In vitro plantlets (8 cm in height) were transplanted to a hydroponic culture with the nutrient film technique (NFT). In soil culture, the plantlets were transplanted to small pots containing sand: burned rice husk: peat moss (1:1:1 by volume). Vegetative growth characteristics were measured at 15, 30, 45 and 60 days after transplanting (DAT), whereas reproductive growth and physiological characteristics were measured at 60 DAT. All there was 100% survival in both growth conditions. Plants of both species grown in hydroponic conditions had higher shoot length, leaf area and stem diameter, except number of shoots than when propagated in soil conditions. Moreover, both species grown in hydroponics had earlier inflorescences and more flowers, indicating that they can be flowering out of season. Additionally, in hydroponic conditions both species had significant higher stomatal conductivity, whereas there were no significant differences in photosynthetic rates, transpiration rates and leaf temperature when compared with soil conditions. Therefore, our study provides evidence that G. schomburgkii and G. marantina are capable of adapting to hydroponic conditions and that hydroponics may be a suitable method for propagating Globba and other ginger plant species into cut flower or potted plants all year round.