Browsing by Author "Kawai, Shigenao"

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Cadmium Phytoextraction Efficiency of Arum (Colocasia antiquorum), Radish (Raphanus sativus L.) and Water Spinach (Ipomoea aquatica) Grown in Hydroponics
(Water Air Soil Pollut, 2008) Abul Kashem, Md.; Singh, Bal Ram; Huq, S. M. Imamul; Kawai, Shigenao
Selection of a phytoextraction plant with high Cd accumulation potential based on compatibility with mechanized cultivation practice and local environmental conditions may provide more benefits than selection based mainly on high Cd tolerance plants. In this hydroponics study, the potential of Cd accumulation by three plant species; arum (Colocasia antiquorum), radish (Raphanus sativus L.) and water spinach (Ipomoea aquatica) were investigated. Arum (Colocasia antiquorum L.) plants were grown for 60 days in a nutrient solution with 0, 10 or 50 μM Cd, while radish and water spinach plants grew only 12 days in 0, 1.5, 2.5, 5 or 10 μM Cd. Growth of radish and water spinach plants decreased under all Cd treatments (1.5 to 10 μM), while arum growth decreased only at 50 μM Cd. At 10 μM Cd treatment, the growth of arum was similar to the control treatment indicating higher tolerance of arum for Cd than radish and water spinach. Cadmium concentrations in different plant parts of all plant species increased significantly with Cd application in the nutrient solution. Arum and water spinach retained greater proportions of Cd in their roots, while in radish, Cd concentration in leaves was higher than in other plant parts. Cadmium concentrations in arum increased from 158 to 1,060 in the dead leaves, 37 to 280 in the normal leaves, 108 to 715 in the stems, 42 to 290 in the bulbs and 1,195 to 3,840 mg kg−1 in the roots, when the Cd level in the solution was raised from 10 μM Cd to 50 μM Cd. Arum accumulated (dry weight×concentration) 25 mg plant−1 at 10 μM, while the corresponding values for radish and water spinach were 0.23 and 0.44 mg plant−1, respectively. With no growth retardation at Cd concentrations as high as 166 mg kg−1 measured in entire plant (including root) of arum at 10 μM Cd in the nutrient solution, arum could be a potential Cd accumulator plant species and could be used for phytoremediation.
Comparison of digesting capacity of nitric acid and nitric acid-perchloric acid mixture and the effect of lanthanum chloride on potassium measurement
(Nature and Science, 2010) Shaibur, Molla Rahman; Abul Hasnat, Md. Shamim; Huq, S. M. Imamul; Kawai, Shigenao
Nitric acid-perchloric acid mixture is the renowned digesting reagent in the scientific world of plant nutrition. Beside this, some other inorganic acids can be used as the digester of plant samples. Therefore, this experiment was conducted to find out if there is any difference between the digesting capacity of nitric acid (HNO3) and nitric acid-perchloric acid mixture (HNO3-HClO4) or not. The hydroponic experiments were conducted with barley (Hordeum vulgare L. cv. Minorimugi) and rice (Oryza sativa L. cv. Akihikari) seedlings. At suitable stage, the plant samples were collected, washed with deionized water, separated into shoot and root, dried, grinded and then divided into two groups for shoot and root individually for two types of seedlings. One group was for only HNO3 acid and the other group was for HNO3-HClO4 acid mixture. Phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn) and copper (Cu) were measured after digesting the samples. There was no significant difference between the digesting capacity of HNO3 acid and HNO3-HClO4 acid mixture. Potassium was measured by diluting the samples (200-600 times) containing lanthanum chloride (LaCl3) or without LaCl3. Lanthanum chloride did not have any significant effect on K measurement in this dilution system.
Critical Toxicity Level of Arsenic and Elemental Composition of Arsenic-Induced Chlorosis in Hydroponic Sorghum
(Water Air Soil Pollut, 2008) Molla Rahman, Shaibur; Kitajima, Nobuyuki; Sugawara, Reiko; Kondo, Toshihito; Alam, Shah; Huq, S. M. Imamul; Kawai, Shigenao
Physiological and mineralogical responses of sorghum (Sorghum bicolor L. cv. Fast sorghum) in hydroponic culture at elevated concentrations of arsenic (As) were valuated. Seedlings were grown in the presence of 0, 6.7, 33.5 and 67 µM As levels (0, 0.5, 2.5 and 5 mg As l −1 ) up to 14 days after treatments (DAT). Shoot and root dry matter yield were repressed by higher As levels. At low As level (6.7 µM) shoot dry matter yield was enhanced by 2.3% but at 33.5 and 67 µM As levels, the yield decreased by 52 and 79%, respectively. The root growth was similarly enhanced (8%) at the lower As level while the growth decrement at the higher As levels were 33 and 68%, respectively for the two treatments. Considering 10% dry weight (DW) reduction, the critical toxicity level of As was calculated to be 11.7 µg g −1 DW for shoot and 367 µg g −1 DW for root, indicating that shoot was more sensitive to As-toxicity than root. A whitish chlorotic symptom was observed in the fully developed young leaves at the 67 µM As level. The lowest chlorophyll content was also observed at this As level. Arsenic oncentration increased both in shoot and in root with increase in solution As concentration. The concentrations of As and Fe were about 16, 28 and 17 times; and 2, 25 and 144 times higher in root than shoot at 6.7, 33.5 and 67 µM As levels, respectively. The concentrations of K, Fe and Cu were significantly lower while Ca, Mg and Mn oncentrations were higher in the shoot at the 67 µM As level compared to the control plants. On the other hand, Fe, Mn, Zn and Cu concentrations were higher in root at the 67 µM As level. In the shoot, accumulation and translocation of metal micronutrients, particularly that of Fe, decreased significantly because of the presence of As. The resent observations suggested that As might induce a toxic effect on sorghum by hampering the translocation of the metal micronutrients. It is suggested that “As-induced e-deficiency” caused chlorotic symptoms in the hydroponically grown sorghum.
Effects of applying calcium salts to coastal saline soils on growth and mineral nutrition of rice varieties
(Journal of Plant Nutrition, 2002) Alam, Shah; Huq, S. M. Imamul; Kawai, Shigenao; Islam, Aminul
Mechanism of Potassium Alleviation of Manganese Phytotoxicity in Barley
(Journal of Plant Nutrition, 2005) Alam, Shah; Akiha, Fumihito; Kamei, Shigeru; Huq, S. M. Imamul; Kawai, Shigenao
Manganese (Mn) toxicity and potassium (K) deﬁciency are the major factors that limit plant growth and development in acid soils. The objective of this study was to assess the role of high K on the alleviation of Mn toxicity in barley (Hordeum vulgare L. cv. ‘Minorimugi’) grown in a phytotron for 14 d. Modiﬁed half-strength HoaglandArnon solution (pH 5.5) was used as the medium. The treatments were (1) 0.25 µM Mn + 3mMK (control); (2) 25 µMMn+ 3mMK(Mn-toxic); and (3) 25 µM Mn+ 30 mM K (K-alleviated). The Mn-toxic plants showed the symptoms of Mn toxicity and mild iron (Fe) deﬁciency, whereas in the K-alleviated plants such symptoms were absent. The K-alleviated plants had dry weight, chlorophyll content, and Fe concentration similar to that in the control plants, indicating that high K (30 mM) in the growth medium could alleviate Mn toxicity and Mn-induced Fe deﬁciency. Roots of plants fed separately with 54 Mn and 59 Fe in the presence of 3.0 and 30 mM K for 4hwere also studied. Results showed that high K could help in avoiding the accumulation of 54 Mn, indicating that K plays an antagonistic role on Mn absorption by roots of barley and its subsequent translocation to the shoots. However, the absorption of 59 Fe was not inﬂuenced by the high K concentration in a short-term experiment (4 h), indicating that high K does not affect short-term Fe absorption by the roots of barley plants. These results suggested that the alleviating effect of high K could be attributed to the antagonistic effect of K on Mn absorption by roots and translocation into shoots.
Physiological and Mineralogical Properties of Arsenic-Induced Chlorosis in Barley Seedlings 3 Grown Hydroponically
(Journal of Plant Nutrition, 2008) Molla Rahman, Shaibur; Kitajima, Nobuyuki; Sugawara, Reiko; Kondo, Toshihito; Huq, S. M. Imamul; Kawai, Shigenao
The experiment was carried out to investigate the effects of arsenic (As) on the physiological and mineralogical properties of barley (Hordeum vulgare L. cv. ‘Minorimugi’). The plants were grown in nutrient solution treated with 0, 6.7, 33.5, and 67 µMAs(0, 0.5, 2.5, and 5 ppm As, respectively) in the phytotron. Dry matter yield of shoots and roots decreased signiﬁcantly with the As treatments, indicating that barley plants are As-sensitive and As-toxicity depends on the As concentration in the rooting medium. Necrosis in older leaves and chlorosis symptoms (whitish color) in the fully developed young leaves were observed at the 33.5 and 67 µMAstreatments. Arsenic concentration, accumulation, and translocation increased with the increase of As concentration in the rooting medium. Arsenic was mostly concentrated in roots and a little amount wasmoved to shoots, indicating that As was not easily translocated to shoots of barley seedlings. Concentrations and accumulations of phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), manganese (Mn), zinc (Zn), and copper (Cu) decreased signiﬁcantly in shoots for 33.5 and 67 µMAstreatments as compared to the 0 µMAstreatment. Concentrations of P, K, Ca, Mg, Mn, and Cu decreased in roots, but Zn concentration increased in roots at 67 µMAstreatment. Accumulations of P, K, Ca, Mg, Mn, Zn, and Cu in roots also decreased signiﬁcantly at 67 µMAstreatment. Accumulation of P and the cations showed negative relationship with As. Concentration of Fe decreased in shoots at 33.5 and 67 µMAstreatments where chlorosis was induced in the young leaf but increased in roots at 33.5 and 67 µMAstreatments. It was suggested that Asmight induce iron (Fe)-chlorosis in the plants. Among the micronutrients, Fe translocation was more affected than others by As. Phytosiderophore (PS) accumulation in roots, which is a symptom of Fe-deﬁciency in grasses, did not change signiﬁcantly between 0 and 33.5 µMAstreatments; indicating that As-induced chlorosis did not enhance PS accumulation in roots and decreased due to As-toxicity at 67 µMAstreatment.
Physiological and mineralogical properties of arsenic-induced chlorosis in rice seedlings grown hydroponically
(Soil Science and Plant Nutrition, 2006) Molla Rahman, Shaibur; Nobuyuki, Kitajima; Reiko, Sugawara; Kondo, Toshihito; Huq, S. M. Imamul; Kawai, Shigenao
A hydroponic experiment was conducted to observe the effect of arsenic (As) on a umber of physiological and mineralogical properties of rice (Oryza sativa L. cv. Akihikari) seedlings. Seedlings were treated with 0, 6.7, 13.4 and 26.8 mol L−1 As (0, 0.5, 1.0 and 2.0 mg As L−1) for 14 days in a greenhouse. Shoot dry matter yield decreased by 23, 56 and 64%; however, the values for roots were 15, 35 and 42% for the 6.7, 13.4 and 26.8 mol L−1 As treatments, respectively. Shoot height decreased by 11, 35 and 43%, while that of the roots decreased by 6, 11 and 33%, respectively. These results indicated that the shoot was more sensitive to As than the root in rice. Leaf number and width of leaf blade also decreased with As toxicity. Arsenic toxicity induced chlorosis symptoms in the youngest leaves of rice seedlings by decreasing chlorophyll content. Concentrations and accumulations of K, Mg, Fe, Mn, Zn and Cu decreased significantly in shoots in the 26.8 mol L−1 As treatment. However, the concentration of P increased in shoots at 6.7 and 13.4 mol L−1 As levels, indicating a cooperative rather than antagonistic relationship. Arsenic and Fe concentration increased in roots at higher As treatments. Arsenic translocation (%) decreased in the 13.4 and 26.8 mol L−1 As treatments compared with the 6.7 mol L−1 As treatment. Arsenic and Fe were mostly concentrated in the roots of rice seedlings, assuming co-existence of these two elements. Roots contained an almost 8–16-fold higher As concentration than shoots in plants in the As treatments. Considering the concentration of Mn, Zn and Cu, it was suggested that chlorosis resulted from Fe deficiency induced by As and not heavy-metal-induced Fe deficiency.