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Rice grain quality and yield, which are adversely affected by suboptimum condition in the climatic environment, are expected to be affected more severely under climate change. Adaptation to climate variation therefore requires stability in grain quality as well as yield. Grain yield and quality of four modern rice varieties were shown to respond differently to the climatic condition of the wet, cool and hot season at Chiang Mai, Thailand. The variation in grain yield was associated with differential effects of season on grain filling in different varieties. A simple dilution effect on nutritional quality was indicated by inverse relation between grain yield and the concentration of nitrogen, phosphorus, iron and zinc in the endosperm, i.e. the white rice normally consumed by rice eaters. The rice varieties also showed differential response to season in their head rice yield, grain chalkiness and gelatinization temperature, independently of the grain yield. The relationship between head rice yield and grain chalkiness was not significant, although some complex physico-chemistry of the starch was suggested by the correlation between grain chalkiness and gelatinization temperature. The effects of variety and season found here suggested that evaluation of rice genotypes for adaptation to climate change will need to consider grain quality along with grain yield. [ABSTRACT FROM AUTHOR]

This study examined the distribution of iron (Fe) and zinc (Zn) along the grain length of seven rice varieties. The experiment was conducted in a completely randomized design with two factors (variety and grain fraction) and three independent replications. Samples of brown and white rice of six common Thai rice varieties and a high Fe and Zn variety, IR68144, were transversely cut into three fractions per grain (basal, middle, and distal) with approximately the same length in each fraction. The concentration of Fe and Zn was determined by the dry ashing method and quantified using atomic absorption spectrometry. The middle grain fraction of brown rice was found to have the lowest Fe and Zn with greater concentration of Fe and Zn in the basal (embryo end) than the other fractions. The rice varieties differed in the amount of Fe and Zn allocated to different fractions of the endosperm (white rice). The potential for loss of Fe and Zn during milling due to their uneven distribution along the grain length will become more significant when higher nutrient concentrations are involved, such as those achieved by biofortification efforts. Micronutrient distribution needs to be taken into consideration to ensure that rice consumers benefit from Fe and Zn biofortification. [ABSTRACT FROM AUTHOR]

Local upland rice germplasm is an invaluable resource for farmers who grow rice on acidic soils without flooding that benefits wetland rice. In this study, we evaluated the adaptation to soil acidity in common local upland rice varieties from an area with acidic soil in Thailand. Tolerance to hydrogen and aluminium (Al) toxicity was determined by measuring root growth, plant dry weight and phosphorus (P) uptake in aerated solution culture without the supplementation of Al (0 mg/l) at pH 7 and 4 and with the supplementation of 10, 20 and 30 mg Al/l at pH 4. The root growth of upland rice plants grown from farmers' seed was depressed less by Al than that of common wetland rice varieties. Pure-line genotypes of upland rice varieties were differentiated into several classes of Al tolerance, with frequency distribution of the classes that sometimes differed between the accessions of the same varieties. The effect of Al tolerance on root length was closely correlated with depression by Al in root dry weight and whole-plant P content. A source for adaptation to soil acidity for exploitation in the genetic improvement of aerobic and rainfed rice is clearly found among local upland rice varieties grown on acidic soils. However, the variation in tolerance to soil acidity within and among the seed lots of the same varieties maintained by individual farmers as well as among the varieties needs to be taken into consideration. [ABSTRACT FROM AUTHOR]

The Squash Leaf Curl China Virus (SLCCNV) and Tomato Leaf Curl New Delhi Virus (ToLCNDV) are species of Begomovirus (whitefly-vectored Geminiviridae) and cause serious damage to the cucurbit crops of the genus Cucurbita in the areas of South and Southeast Asia, across Asia, the Middle East and the Mediterranean, respectively. Cucurbita moschata's inbred line AVPU1426, developed at the World Vegetable Center (WorldVeg) from a Bangladeshi landrace through pedigree selection, was observed to be resistant to both begomoviruses in field tests conducted at the WorldVeg Research and Training Station, Kasetsart University, Kamphaeng Saen, Thailand, which is a hotspot for these viruses. When AVPU1426 was tested for reaction to inoculation by viruliferous whiteflies with Squash Leaf Curl Philippines Virus (Taiwan strain) (SLCPV-TW) in the screen net-house at WorldVeg headquarters in Taiwan, it showed good resistance, though SLCPV-TW DNA-A could be detected in all inoculated plants, indicating that it did not show immunity to this virus. The objective of this study was to validate the resistance to SLCCNV and ToLCNDV in AVPU1426 by using whitefly-mediated inoculations to determine the mode of inheritance of the resistance. The results showed that AVPU1426 was resistant to SLCCNV and ToLCNDV. Upon crossing AVPU1426 with a susceptible check variety, Waltham Butternut, the resistance to both begomoviruses was observed to be conferred by a single recessive gene. This open-pollinated pumpkin line AVPU1426 bears flat round, mottled green immature fruits with yellow flesh in mature fruit. The fruit yield of AVPU1426 (20.74 t/ha−1) was comparable to 'Rajah' (18.61 t/ha−1), a recently released commercial F1 hybrid of East-West Seed (EWS). The fruit of AVPU1426 were estimated to have a good average β-carotene content (1.57 mg/100 g fresh weight). This line is a good source to breed pumpkins resistant to the three begomoviruses. [ABSTRACT FROM AUTHOR]

The mission of the World Vegetable Center (WorldVeg) is research and development to realize the potential of vegetables for healthier lives and more resilient livelihoods. WorldVeg operates across Asia and Africa, and its breeding portfolio comprises global as well as traditional vegetables. Cucurbit crops make an important contribution to global food and nutrition security and are economically important to smallholder farmers in Asia, who account for 83% of global cucurbit production. The global cucurbit breeding program of WorldVeg focuses on four species: bitter gourd (Momordica charantia), tropical pumpkin (Cucurbita moschata), ridge gourd (Luffa acutangula), and sponge gourd (Luffa cylindrica syn. L. aegyptiaca). Improved cultivars have been developed by the private seed industry, however, repeated recycling of lines derived from elite hybrids has narrowed the genetic base and reduced genetic gains for yield and other key traits. This trend will continue unless a concerted effort is made to introduce new genetic variability into elite hybrids. WorldVeg has organized a breeding consortium with seed companies to facilitate access to the Center's new breeding lines derived from hitherto unexploited landraces to develop genetically diverse, improved cucurbit cultivars with enhanced yield and resistance to major diseases. Through this partnership, WorldVeg presents its improved lines and F1 hybrids at Crop Field Days for selection by private seed industry staff engaged in breeding, product development, and sales and marketing. [ABSTRACT FROM AUTHOR]

Cucurbit powdery mildew (CPM) caused by Podosphaera xanthii (Px) is an economically important disease of bitter gourd (BG; Momordica charantia) in Asia. Highlevel resistance to CPM is known in various BG accessions that have been used to develop BG breeding lines that originated in different countries. BG breeding lines THMC 113 (Belize), THMC 143 (India), THMC 153 (Thailand), THMC 167 (India), and THMC 170 (Taiwan) possess high-level resistance to BG Px race (BG-CPM), designated Mc-1 from a field at Kamphaeng Saen, Thailand, whereas THMC 144 (India) is susceptible. Our objective was to determine the inheritance of resistance to BG-CPM race Mc-1. To that end, THMC 144 (India) was crossed with the five resistant lines. The parents and their respective F1, F2, backcross progenies were evaluated for BG-CPM disease severity in inoculated field and growth chamber tests. Resistance to BG-CPM race Mc-1 in the five resistant lines was controlled by at least two independent, recessive genes. Intercrosses of the BG-CPM-resistant lines revealed allelic resistances in four of the breeding lines: THMC 113, THMC 153, THMC 167, and THMC 170. Resistance in THMC 143 was clearly non-allelic for resistance to BG-CPM with the other four BG-CPM-resistant lines. [ABSTRACT FROM AUTHOR]