Nutritional and physicochemical properties of new giant embryo mutant rice (YR23517Acp79, YR) were analyzed. YR exhibited increased total protein (9.3±0.3%), lipid (3.7±1.1%), amino acid (663.28±1.9 mg/g), and mineral contents (Ca=284.0±6.2, Mg=1417.5±13.6 mg/kg). In YR brown rice four major physicochemicals, including gamma-aminobutyric acid (brown rice= 0.46±0.014 mg/g), γ-oryzanol (0.43±0.021 mg/g), vitamin B 1 (6.42±0.3 mg/kg), and tocopherols (alpha= 2.68±0.1, beta=0.11±0.01, gamma=0.05±0.001 mg/100 g) increased in comparison to reported giant embryo (Keunnunbyeo, KB) and normal embryo rice (Ilmibyeo, IB). YR showed higher scavenging activities against 1,1-diphenyl-2-picrylhydrazyl (0.2 g/mL=57.1±2.25) and 2,2'-Azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (0.2 g/mL=50.2±1.45) radicals but also inhibited lipopolysaccharide-induced nitric oxide production without cytotoxicity. These results indicate YR is a high quality functional rice due to its high nutrition content and antioxidant effects of physicochemicals.

We studied changes in the chlorophyll (Chl) fluorescence components in chilling-stressed sweet potato (Ipomoea batatas L. Lam) cv. Tainung 57 (TN57, chilling-tolerant) and cv. Tainung 66 (TN66, chilling-susceptible). Plants under 12-h photoperiod and 400 μmol m -2 s -1 irradiance at 24/20 °C (day/night) were treated by a 5-d chilling period at 7/7 °C. Compared to TN66, TN57 exhibited a significantly greater basic Chl fluorescence (F 0 ), maximum fluorescence (F m ), maximum fluorescence yield during actinic irradiation (F m '), and the quantum efficiency of electron transport through photosystem 2, PS2 (Ф PS2 ). Chilling stress resulted in decrease in the potential efficiency of PS2 (F v /F m ), Ф PS2 , nonphotochemical fluorescence quenching (NPQ), non-photochemical quenching (q N ), and the occurrence of chilling injury in TN66. Chilling increased the likelihood of photoinhibition, characterized by a decline in the Chl fluorescence of both cultivars, and photoinhibition during low temperature stress generally occurred more rapidly in TN66.Additional key words: cultivar differences; Ipomoea; photosystem 2; quantum yield. --Under natural conditions, photosynthesis is regulated biochemically to maintain a balance between the rates of its component processes and concentrations of metabolites in response to environment changes (Singsaas et al. 2000). Chloroplasts are the major target of many environmental stress factors. Plants respond to sudden and sustained fluctuations in irradiance and high and low temperatures via their chloroplast molecular redox signalling transduction mechanisms that initiate and network to induce marked modulations in chloroplast components, ultimately leading to acclimation of the photosynthetic apparatus (Anderson et al. 1997). Plants adapt photosynthesis within a certain range to prevailing environment, and the sensitivity of photosynthesis to stress varies among plant species and cultivars. Chilling stress reduces the capacity of photosynthetic systems to utilize incident photons and leads to photoinhibition (Jung et al. 1998). Photoinhibition of photosynthesis is characterized by a reduction in the quantum yield of photochemistry and a decrease in chlorophyll (Chl) fluorescence. Photoinhibition entails not only the inhibition of photosystem 2 (PS2) but also increases thermal de-excitation of excited Chl (Demmig-Adams and Adams 1992). Photoinhibition of photosynthesis has been reported for chillingsusceptible plants under high irradiance at chilling temperatures of 0-15 °C. Furthermore, annual plants of temperate regions undergo photoinhibition in winter when they are exposed to moderate irradiance at chilling temperatures (Somersalo and Krause 1989). Several indicators support this assumption: periods of low temperature are accompanied by a lower Chl content, decreased activities of Calvin cycle enzymes, poor development of the chloroplasts, an increased pool size of xanthophyll pigments, reduced photosynthetic capacity, decreased quantum efficiency of PS2 and CO 2 fixation, and increa...

Transplanting is an important rice cultivation method; however, transplanting shock commonly affects grain yield, and the mechanisms underlying the inhibition of growth, development, and delayed heading caused by transplanting shock have not yet been clearly elucidated. Here, we investigated the effects of seedling age, temperature, and root damage during transplanting on growth, development, and time to heading, both under artificially controlled and natural day length. Additionally, we investigated the impact of seedling root growth space and the potential mitigating effects of residual seed nutrients on young transplanted seedlings. The delay in heading in transplanted versus directly seeded plants was affected more by growth inhibition during the seedling period than by root damage during transplanting. However, root damage had an effect on the inhibition of leaf and tiller development, and the ratio of leaves to tillers increased because tiller development was inhibited more by transplanting shock compared with leaf development. Based on these findings, we propose factors reflecting the delay in growth due to transplanting shock that should be included for more accurate rice phenology modeling and suggest advantageous seeding conditions and transplanting methods for improved rice cultivation and yield in response to climate change.

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