Laila Khandaker

Abstract: This study was conducted to determine the effect of foliar salicylic acid (SA) applications on growth, yield and bioactive compounds of red amaranth grown under greenhouse conditions in 2008 at Gifu University, Japan. SA was applied at three different concentrations (10-3, 10-4 and 10-5 M), three times during the vegetation at 7-day intervals one week after sowing. Growth parameters (plant height, stem length, number and size of leaves, root length) and yield (fresh and dry matter weight) were recorded from treated and control plants on 28 days after sowing. Among bioactive compounds, betacyanins, chlorophyll, total polyphenol and antioxidant activity were the determined from the leaves of treated and control plants. All of three doses SA application enhanced the plant growth, yield and leaf’s bioactive compounds compared to the control. The growth parameters and yield of red amaranth was significantly influenced by foliar SA applications. The highest yield, antioxidant activity, amount of betacyanins, chlorophyll and total polyphenol occurred in 10-5 M SA treatment. According to our results, applications of 10-5 M SA should be recommended in order to improve yield and bioactive compounds in red amaranth.

Abstract: The objectives of this study were to determine the effects of daily air temperature and sunlight intensity variations on biomass production, leaf color and betacyanin accumulations in red amaranth (Amaranthus tricolor L.). For this purpose, two improved cultivars; BARI-1 and Altopati were grown in seven different period (from April to October, 2006) under vinyl house condition in the experimental facilities of Gifu University, Japan. The mean daily temperatures fluctuated from 18 (growing month- April) to 29ºC (August), while the mean sunlight intensities varied from 850 (October) to 1257 μmol m-2 S-1 (August). The highest biomass yield and betacyanin accumulation was obtained in the warmer growing period (July and August) at 28 to 29ºC mean air temperatures and 1240 to 1257 μmol m-2 S-1 sunlight intensity. At the warmer growing period red amaranth produced red leaves with high color index, which enhanced the betacyanin accumulations. The biomass yield and betacyanin accumulations were reduced significantly in the growing period/month April and October under low temperature regimes (mean air temperature 18 and 19ºC, respectively). However, growing period’s air temperature contributed more for biomass and betacyanin accumulations in red amaranth than sunlight intensity. Comparing two cultivars the biomass yield of BARI-1 was higher biomass yield than that of Altopati and Altopati highlighted with the higher betacyanin accumulations than that of BARI-1 in all growing period. Quantification of the effects of daily air temperature and sunlight intensity on biomass and betacyanin accumulation is important for growers producing these crops for fresh market and also optimize the best growing period. Therefore the influence of air temperatures and sunlight intensity should be considered while grown red amaranth for maximum yield with bioactive compounds like betacyanin and should be grown in between 28 to 29ºC air temperature and 1240 to 1257 μmol.m-2.S-1. of sunlight intensity.

Abstract: The anthocyanin, total polyphenol and antioxidant activity of 29 common bean from diverse origins and seed coat color, was assessed. Among the bean genotypes, fourteen were developed by CIAT in various interests; thirteen were from the USA, representing several market classes and one each from Brazil and India. The seeds of included genotypes have shown distinction in shape, color and seed weight. The variations of seed color are white, cream, purple, red and black, with variations being striped, rhomboid spotted and circular mottled. Bean genotypes exhibited distinguishing differences in anthocyanin, total polyphenol and antioxidant activities. Anthocyanin content varied significantly among genotypes and market classes, ranging from 0.05 to 0.47 mg g-1. The bean genotypes with total polyphenol content ranging from 5.87 to 14.14 mg of gallic acid equiv/g and the sample also exhibited significant variation in antioxidant activity (17.09 to 36.96%). Considering the profile of bioactive compounds the genotypes T-39, XAN 176, BAT 93 and MIB 154 are promising. Generally bean genotypes with high anthocyanin and polyphenol content exhibit high antioxidant activity. The information of this study can be used for selecting superior bean genotypes for targeted food and feed purposes and also for a breeding program.

Abstract: Nine wheat varieties (Shatabdi, Showrav, Protiva, Ahgrani, Kanchan, Akbar, Barkat, Sonalika, Kheri) from Bangladesh were analyzed for determination of total polyphenol (TP), polyphenoloxidase (PPO), antioxidant activities (AA) and color index (CI). The highest TP (1.316 mg /gm GAE) and AA (14.58%) determined in Shatabdi and PPO (0.295 U × ml-1 × min) in Barkat. The lowest TP (1.280 mg /gm GAE), PPO (0.145 U × ml-1 × min) was determined in Akbar and the lowest AA (7.64%) was in Sonalika . Least color index was obtained in Akbar but good color parameters for wheat like brightness and yellowness values were found higher in Shatabdi. There was stronger correlation found between AA and TP than among TP, AA, PPO and CI. Comperatively new released varieties, Protiva, Shourav (BARI Gom-19) and Shatabdi (BARI Gom- 21) have higher level of TP, AA with brighter color profile.

Abstract: This study was conducted to determine the betacyanin, chlorophyll, total polyphenol, antioxidant activity and leaf color parameters of three edible amaranth (Amaranthus tricolor L. subsp. mangostanus L. Allen) cultivars grown under five different shade levels. Red-fleshed leaf cultivars Rocto Alta and Altopati and a greenfleshed leaf cultivar SAT-072 were grown in the open field (no shading) and four selected shading regimes covered by one layer of white, one layer of black, two layers of black and four layers of black neutral density synthetic shading clothes, respectively. The contents of betacyanin, chlorophyll and total polyphenol and antioxidant activity were measured from leaf extracts. Leaf pigments were evaluated in relation to leaf color parameters: lightness (L*), redness (a*) yellowness (b*), chroma (C*) and hue angle (H0). The highest content of betacyanin, chlorophyll and total polyphenol and antioxidant activity were found in red-fleshed leaf cultivars grown in full sunlight (open shade). Comparatively, red-fleshed leaf cultivars contained higher amount of pigments, total polyphenol and antioxidant activity than green-fleshed leaf cultivar when exposed to different levels of shade. Highly and strong positive correlations were observed among betacyanin, chlorophyll, total polyphenol and antioxidant activity in red-fleshed leaf cultivars compared to green-fleshed leaf cultivar under different shading conditions. The leaf color of ‘Rocto Alta’ and ‘Altopati’ gradually changed from red to green with the increasing levels of shade. The variations of pigments caused the wider range of color parameters on red leaf cultivars than on green leaf cultivar.

Abstract: Seven cultivars of red amaranth (Amaranthus tricolor L.) with different leaf color were evaluated for their betacyanin and chlorophyll content at two stages of development. The effects of food processing factors such as thermal treatment, light, H2O 2, and prolonged storage on betacyanin extracts were also examined. Betacyanin concentrations were highly correlated with the leaf color index and the cultivars (Rocto joba, BARI-1, and Altopati) with better color index tended to be associated with high betacyanin. Within a shoot canopy, the apical leaves accumulated higher betacyanin than those of middle and basal leaves. While the highest concentrations of chlorophyll were found in BARI-1, however Red queen had the lowest concentrations. Color index of leaves and betacyanin concentrations were increased and chlorophyll concentrations were decreased with the plant age, which indicate that change of these colorant pigment concentrations with plant age enhance the red leaf formation in red amaranth. Low temperature, darkness, and free or low oxidants maintained the stability of betacyanin concentrations of red amaranth; prolonged storage degraded the betacyanin. Variable factors such as the cultivar of red amaranth, its degree of maturity, and the food processing factors have been shown to have a quantitatively important influence on betacyanin yields and preservation.

Abstract: Five selected leafy vegetables with different leaf color were evaluated for their functional components, antioxidant activity and color parameters grown under different levels of photoperiod. All vegetable plants were grown in controlled chamber under the levels of photoperiod as 6, 12, 18 and 24 hours. The leaves of vegetables plant contained the highest content of betacyanin, chlorophyll, total polyphenol and antioxidant activity under a 12 hour and the lowest was found in a 24 hour photoperiod. The highest contents at every photoperiodic level were in the order of red amaranth>red beet>swiss chard>red spinach>green amaranth for betacyanin; red amaranth>red spinach>swiss chard>red beet>green amaranth for chlorophyll ; red beet>swiss chard>red spinach>red amaranth>green amaranth for total polyphenol. The highest antioxidant activity was found in red amaranth as followed by red beet, red spinach and swiss chard under a 12 hour photoperiod, while green amaranth had the lowest activity at every photoperiodic levels. Strong positive correlations among functional components and antioxidant activity suggest that combined functions of both enhanced the best antioxidant activity under a 12 hour photoperiod. The deeper color (higher redness value and lower yellowness value) with lower lightness value in red-fleshed leafy vegetables and the brighter color (lower redness value and higher yellowness value) with higher lightness value in green amaranth were observed under different photoperiodic levels. Compared to the other studied vegetable species, red amaranth was more sensitive to the variation in betacyanin than in chlorophyll content.

Abstract: Biomass yield and accumulations of betacyanin, chlorophyll, total polyphenol, and antioxidant activity were evaluated growing red amaranth (Amaranthus tricolor L.) in spring season under five different shades made of white, blue, green, yellow, and black polyethylene, and non-shaded frame. Temperature and light intensity varied significantly (P < 0.05) under the different colored polyethylene shades, and these differences in microclimate are implicated for the variability in growth and accumulations of bioactive compounds. The highest temperature was obtained under the blue polyethylene shade and the plants achieved highest plant height, stem length and leaf number, fresh and dry matter biomass, betacyanins, total polyphenol, and antioxidant activity. The achieved biomass yield and accumulation of bioactive compounds were almost similar to field grown red amaranth in summer season. Blue polyethylene shade has probably ensured the optimum microclimate for growth and development of red amaranth in the studied growing period. Exceptionally the plants grown under green polyethylene shade accumulated highest chlorophyll. Although non-shaded plants received highest sunlight intensity but gave the poor biomass yield as well as accumulated less bioactive compounds than plants grown under blue polyethylene shade due to low air temperature. Thus, the results indicated that blue polyethylene has potentials to increase the yield with health beneficiary bioactive compounds betacyanins, polyphenol and antioxidant activity during the low temperature regime in spring season.

Abstract: The total polyphenol content and antioxidant activity were compared in the leaves of seven red amaranth (Amaranthus tricolor L.) cultivars. The effect of the sunlight level on the accumulation of total polyphenol content and antioxidant activity was also investigated by growing plants under full sunlight and shaded conditions. The total phenolic content and antioxidant activity differed among the cultivars studied, and leaves from the cultivar ‘Rocto Joba’ and ‘Rocto Lal’ had the highest phenolics and antioxidant activity, respectively. These values were lowest in the leaves of the cultivar ‘Red Queen’. Comparatively, red-fleshed cultivars had more total polyphenols and antioxidant activity than red green-fleshed cultivars. Total polyphenol and antioxidant activity were greater in leaves from plants grown under full sunlight without shading. The positive correlation between antioxidant activity and total polyphenols (R2 = 0.824) suggests that phenolic compounds are the major antioxidant components in red amaranth. The results indicate that red amaranth containing high phenolics may provide a source of dietary antioxidants. The combination of cultivar variation and responsiveness to specific growing conditions can create opportunities for the production and processing of vegetable red amaranth with improved antioxidant properties.