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The response spectrum for green light induced-acceleration of heading in wheat cv. Norin 61 was investigated using narrow-bandwidth (10 nm) green light within the range of 520–550 nm. Heading was observed from approximately 30 days after emergence. The earliest heading was observed at 540 nm, which suggests the presence of a green light photoreceptor different from hitherto known photoreceptors.

Soil and water contaminated with arsenic (As) pose a major environmental and human health problem in Bangladesh. Phytoremediation, a plant-based technology, may provide an economically viable solution for remediating the As-polluted sites. The use of indigenous plants with a high tolerance and accumulation capacity for As may be a very convenient approach for phytoremediation. To assess the potential of native plant species for phytoremediation, plant and soil samples were collected from four As-contaminated (groundwater) districts in Bangladesh. The main criteria used for selecting plants for phytoremediation were high bioconcentration factors (BCFs) and translocation factors (TFs) of As. From the results of a screening of 49 plant species belonging to 29 families, only one species of fern (Dryopteris filix-mas), three herbs (Blumea lacera, Mikania cordata, and Ageratum conyzoides), and two shrubs (Clerodendrum trichotomum and Ricinus communis) were found to be suitable for phytoremediation. Arsenic bioconcentration and translocation factors > 1 suggest that these plants are As-tolerant accumulators with potential use in phytoextraction. Three floating plants (Eichhornia crassipes, Spirodela polyrhiza, and Azolla pinnata) and a common wetland weed (Monochoria vaginalis) also showed high BCF and TF values; therefore, these plants may be promising candidates for cleaningup As-contaminated surface water and wetland areas. The BCF of Oryza sativa, obtained from As-contaminated districts was > 1, which highlights possible food-chain transfer issues for As-contaminated areas in Bangladesh.

Wheat (Triticum aestivum L. cv. Norin 61) plants were grown under five different photon flux densities obtained by modulating the number of green light-emitting diodes (LEDs) under white fluorescent lamps. The experiment was conducted under continuous irradiation at a constant temperature of 20°C to clarify the developmental responses of wheat to the fluence rate of green light. The higher the photon flux density of green light, the shorter the number of days from emergence to heading. The earliest heading was observed in the plants grown under 496 green LEDs, 32.0 days after emergence. A significant logarithmic function could fit the relationship between the fluence rate of green light and developmental rate. In this report, principal component analysis (PCA) was adopted to analyze the confounding of green light versus photosynthetic photon flux density (PPFD) with 17 developmental and morphological traits. The eigenvalues explained were 5.64, 3.20, and 2.61, respectively, for the first, second and third principal components (PCs). The first PC was assumed as the factor related to the isometric growth, and the third PC was assumed as the factor related to the developmental rate and culm elongation. Therefore, it was supposed that the first and third PCs were affected by the PPFD and the photon flux density of green light, respectively. The results suggested that the fluence rate of green light affects the development of wheat as a signal source. Furthermore, the development of wheat was promoted by the green light independent of PPFD.

The developmental rate of wheat was investigated under continuous light of eight different qualities (in eight plots) obtained by combining three out of four different kinds of fluorescent lamps (white, blue, purplish red and ultraviolet-A) at a constant temperature of 20°C. A Japanese spring wheat var. Norin 61 and a winter wheat var. Shun-yo were used. The number of days from seeding to heading varied extensively with the variety and the light quality. The first heading was observed in the plot under three white fluorescent lamps (W + W + W) at 37 and 81 days after seeding in Norin 61 and Shun-yo, respectively. The developmental rate in both cultivars was significantly correlated with the ratio of energy in 500-550 nm range (green light) and 600-700 nm range (red light) to that in the whole spectral range (250-1,000 nm). These results suggest that green and red lights play important roles in the regulation of the developmental rate independent of photoperiodism and vernalization.