Md. Amzad Hossain

Potential Use of Halophytes to Remediate Saline Soils

Salinity is one of the rising problems causing tremendous yield losses in many regions of the world especially in arid and semiarid regions. To maximize crop productivity, these areas should be brought under utilization where there are options for removing salinity or using the salt-tolerant crops. Use of salt-tolerant crops does not remove the salt and hence halophytes that have capacity to accumulate and exclude the salt can be an effective way. Methods for salt removal include agronomic practices or phytoremediation. The first is cost- and labor-intensive and needs some developmental strategies for implication; on the contrary, the phytoremediation by halophyte is more suitable as it can be executed very easily without those problems. Several halophyte species including grasses, shrubs, and trees can remove the salt from different kinds of salt-affected problematic soils through salt excluding, excreting, or accumulating by their morphological, anatomical, physiological adaptation in their organelle level and cellular level. Exploiting halophytes for reducing salinity can be good sources for meeting the basic needs of people in salt-affected areas as well. This review focuses on the special adaptive features of halophytic plants under saline condition and the possible ways to utilize these plants to remediate salinity.

Growth, Yield and Quality of Turmeric (Curcuma longa L.) Cultivated on Dark-red Soil, Gray Soil and Red Soil in Okinawa, Japan

Abstract We evaluated growth, yield and quality of turmeric (Curcuma longa L.) cultivated in pots with dark-red soil (pH 5.2), gray soil (pH 7.4) and red soil (pH 4.4) in Okinawa, Japan. The soils were collected from the 50-cm deep layer of the fields. We did not use any chemicals or organic fertilizers. Turmeric cultivated on dark-red soil had the highest plant height, root biomass and shoot biomass as compared with that cultivated on other soil types. Turmeric on dark-red soil had the highest yield with favorable color of the deep yellow and high curcumin content (0.20%). Protein content of turmeric in dark-red soil was 5.2%, which was around 40% higher than that in other soil types. Turmeric cultivated on dark-red and gray soils had a fat content 71% higher than that in red soil. The content of Ca, K and Mg was the highest when turmeric was cultivated on gray soil, and Fe was the highest when cultivated on dark-red soil. To gain a high yield and high contents of curcumin, fat, protein and Fe, we should cultivate turmeric in dark-red soil in Okinawa. We could not recognize the specific soil factor(s) required for high yielding and high quality of turmeric; however, it seems that a proper combination of soil factors, nutrients and/or pH level may be necessary to gain a high yield and high quality.

Effects of Application of N, P and K Alone or in Combination on Growth, Yield and Curcumin Content of Turmeric (Curcuma longa L.)

Crops respond differently to different fertilizer elements, and proper fertilizer management for a plant species is important for increasing yield and quality. Nitrogen (N), phosphorus (P) and potassium (K) are the three major nutrients, which individually and/or together maintain growth, yield and quality of plants (Mazid, 1993; Ivonyi et al., 1997). N is involved in chlorophyll formation, and it influences stomatal conductance and photosynthetic efficiency (Mazid, 1993; Ivonyi et al., 1997). N is responsible for 26-41% of crop yields (Mazid, 1993; Maier et al., 1994, 1996). K plays catalytic roles in the plant rather than becoming an integral part of plant components. It regulates the permeability of cell walls and activities of various mineral elements as well as neutralizing physiologically important organic acids. Plants with an inadequate supply of K show poor fruit or seed formation, yellowing of the leaves, poor growth, and low resistance to coldness and drought (Oya, 1972). A sufficient supply of K promotes N uptake efficiency of plants due to its stimulant effect on plant growth. P indirectly promotes plant growth and absorption of K as well as other nutrients (Oya, 1972). Turmeric (Curcuma longa L.) is used in many countries as a spice and cosmetic (Ishimine et al., 2003; Hossain et al., 2005a, b). It is now a popular medicinal plant worldwide. Curcumin the main component of turmeric functions as a medicine with anti-inflammatory, anti-mutagenic, anti-carcinogenic, anti-tumor, anti-bacterial, anti-oxidant, anti-fungal, anti-parasitic and detox properties (Hermann and Martin, 1991; Osawa et al., 1995; Sugiyama et al., 1996; Nakamura et al., 1998). The efficacy of C. longa found on a specific disease varies with the studies, and in some cases no efficacy was found (Hermann and Martin, 1991; Osawa et al., 1995; Sugiyama et al., 1996; Nakamura et al., 1998). Such differences may be due to variation in the curcumin content which is assumed to depend on the fertilizer elements. Turmeric is a horticultural crop demanding heavy fertilization for increasing yield and quality (Reddy and Rao, 1978; Govind et al., 1990; Yamgar et al., 2001). We reviewed several papers and found that the chemical fertilizers affect growth, yield and quality of turmeric variously, and the effects of N, P and K alone or in combination are not clear, because farmyard manure was used together and some experiments did not include control treatment (Reddy and Rao, 1978; Govind et al., 1990; Yamgar et al., 2001; Behura, 2001). Turmeric is commercially cultivated in Okinawa, but yield per unit area and curcumin content are very poor, because fertilizer management is not well known to the farmers (Hossain and Ishimine, 2005). In previous studies, we evaluated planting depth, time, pattern, seed size and soil types on growth and yield of turmeric in Okinawa (Ishimine et al., 2003, 2004; Hossain et al., 2005a, b; Hossain and Isimine, 2005). The present study was undertaken to evaluate the effects of N, P and K alone or in combination on growth, yield and curcumin content of turmeric.

Optimal Planting Depth for Turmeric (Curcuma longa L.) Cultivation in Dark Red Soil in Okinawa Island, Southern Japan

Abstract Effects of planting depth on emergence, growth, development and yield of turmeric (Curcuma longaL.) in dark red soil (Shimajiri Mahji) were evaluated in Okinawa, Japan. Turmeric planted at the depths of 8, 12 and 16 cm emerged earlier and more evenly than that planted at a shallower depth in both glasshouse and field experiments. Weed growth was unaffected by the planting depth of turmeric until 50-60 days after planting (DAP), but affected thereafter due to mutual shading with the canopy. Weed biomass at 90-140 DAP was significantly smaller in the fields where turmeric was planted at the depths of 8, 12 and 16 cm than in the field where it was planted at a shallower depth. The turmeric rhizome (yield) developed earlier when planted at 8, 12 and 16 cm depths than at 4 cm. In a glasshouse study, shoot biomass and yield of turmeric were significantly greater when planted at the depths of 4, 8 and 12 cm than that of 2 cm. In field experiments, they were also significantly greater when planting depth was 8 or 12 cm than 4 cm. Even in turmeric planted at a 16 cm depth shoot dry weight and yield were greater than that planted at a 4 cm depth, but it was comparatively difficult to harvest rhizomes in this field. About 30% of turmeric in the field planted at a 4 cm depth was uprooted by a typhoon, but not at the depths of 8, 12 and 16 cm. The over all results suggested that rhizomes of turmeric should be planted at a depth of 8 to 12 cm in dark red soil for a higher yield and lower weed competition.

Effects of farmyard manure on growth and yield of turmeric (Curcuma longa L.) cultivated in dark-red soil, red soil and gray soil in Okinawa, Japan.

Chemical fertilizer, herbicide and pesticide used in agriculture for increasing yield and controlling weeds and pests can contaminate the water, air and food, decrease soil fertility, inhibit growth of soil microorganisms and hazard human health (Sharifuddin and Zaharah, 1991; Li et al., 1999; Neera et al., 1999; Erisman et al., 2001). In addition, chemicals may destroy many species of plants, insects, fishes and soil microorganisms (Fantroussi et al., 1999). Therefore, utilization of farmyard manure in agriculture is recommended for retaining productivity of problem soils, reducing the usages of chemical fertilizer, improving economy in agriculture and minimizing environmental problems (Sharifuddin and Zaharah, 1991; Neera et al., 1999; Whalen et al., 2003; Xiao et al., 2006). Turmeric is a horticultural root-crop that is important not only as a spice and cosmetic, but also as a medicinal plant worldwide (Hermann and Martin, 1991; Osawa et al., 1995; Sugiyama et al., 1996; Nakamura et al., 1998; Ishimine et al., 2003; Hossain et al., 2005a, b). Considering the medicinal values of turmeric and environmental problems caused by chemicals application, it is important to cultivate turmeric using organic fertilizer (e.g. farmyard manure). Farmyard manure is regularly applied to many root crops for higher yield (Vanek et al., 2003). The fertilizers derived from animals, plants and microorganisms, are usually called organic fertilizer or farmyard manure. Many kinds of farmyard manure are locally produced based on available natural resources. Chicken manure, goat manure and cow manure are commercially available in Okinawa. Turmeric is commercially cultivated in dark-red soil (Shimahiri maaji), red soil (Kunigami maaji) and gray soil (Jagaru) in Okinawa (Hossain and Ishimine, 2005). Previously, we evaluated planting depth, time, pattern, seed size and soil types on growth and yield of turmeric (Ishimine et al., 2003, 2004; Hossain et al., 2005a, b; Hossain and Ishimine, 2005). Here, we evaluated the effects of farmyard manure on growth and yield of turmeric cultivated in dark-red soil, red soil and gray soil.

Effects of soil types and fertilizers on growth, yield, and quality of edible Amaranthus tricolor lines in Okinawa, Japan

Abstract Soil types and fertilizer regimes were evaluated on growth, yield, and quality of Amaranthus tricolor lines, IB (India Bengal), TW (Taiwan), BB (Bangladesh B), and BC (Bangladesh C) in developing management practices in Okinawa. Growth and yield of all amaranth lines were higher in gray soil (pH 8.4) than in dark red soil (pH 6.6) and red soil (pH 5.4). The combined NPK fertilizer resulted in highest growth parameters and yield of amaranths in all soils. Nitrogen fertilizer alone did not affect growth parameters and yield of amaranths in dark red and red soils. Growth parameters and yield increased similarly with the 30, 40, and 50 g m−2 of NPK fertilizer in BB line, and with the 20, 30, 40, and 50 g m−2 in BC line. Agronomic efficiency of NPK fertilizer at 50 g m−2 was not prominent on the amaranths, compared to the fertilizer at 40 g m−2. Amaranth lines had higher Na in dark red and red soils, while K and Mg in gray soil, Ca in gray and red soils, and Fe in dark red soil. The NPK fertilizer resulted in higher Na, Ca, Mg, and P in BB line in glasshouse. These minerals in BB line were not clearly affected, but in BC line were lower with NPK fertilizer at 20–50 g m−2 in field. These studies indicate that gray soil is best for amaranth cultivation and combined NPK fertilizer at 20–40 g m−2 is effective in gray soil in Okinawa for higher yield and minerals of amaranth.

Antifungal Activity of Various Species and Strains of Turmeric (Curcuma SPP.) Against Fusarium Solani Sensu Lato

Turmeric (Curcuma spp.) are rhizomatous perennial herbs with broad spectrum of pharmacological actions. There are more than 80 species of turmeric and 70 varieties/strains of Curcuma longa, which may have different chemical properties and biological activities. Hence, we compared the major active components (curcuminoides) and antifungal activity of three Curcuma longa strains (Ryudai gold (RD), Okinawa ukon, and BK2), C. xanthorrhiza, C. aromatica, C. amada, and C. zedoaria against Fusarium solani sensu lato (FSSL). The content of curcuminoides was determined by HPLC and the antifungal activity was measured by the diameter of colonies grown on Petri dish, microscopic observation, and CLSI microdilution methods. The BK2 turmeric contained highest concentration of curcumin, demethoxycurcumin, and bisdemethoxycurcumin followed by RD, C. xanthorrhiza, Okinawa ukon, and C. aromatica. These compounds were not detected in C. amada and C. zedoaria. All turmeric species inhibited fungal growth in a concentration-dependent manner. The order of IC50 against FSSL was RD (78 to 92 μg/ml) > BK2 (89 to 101 μg/ml) > C. xanthorrhiza (98 to 114 μg/ml) > C. aromatica (183 to 204 μg/ml) > C. amada (183 to 206 μg/ml) > Okinawa ukon (191 to 216 μg/ml) > C. zedoaria (354 to 385 μg/ml). The results showed a correlation between the antifungal activity and curcuminiods contents of turmeric. Curcumin itself showed marked antifungal activity against FSSL (IC50 = 23 to 25 μg/ml) followed by demethoxycurcumin (IC50 = 25 to 27 μg/ml), while the antifungal activity of bisdemethoxycurcumin was extremely low (IC50 = 216 to 238 μg/ml). However, C. amada and C. zedoaria had no curcuminoids but showed antifungal effects which indicated that other compounds could also inhibit the growth of FSSL. The obtained results demonstrated that turmeric species C. longa (strains Ryudai gold and BK2) and C. xanthorrhiza had higher content of curcuminoids and showed excellent antifungal activity against FSSL.

Antioxidant activity of different species and varieties of turmeric (Curcuma spp): Isolation of active compounds

There are >80 species of turmeric (Curcuma spp.) and some species have multiple varieties, for example, Curcuma longa (C. longa) has 70 varieties. They could be different in their chemical properties and biological activities. Therefore, we compared antioxidant activity, total phenolic and flavonoid content of different species and varieties of turmeric namely C. longa [variety: Ryudai gold (RD) and Okinawa ukon], C. xanthorrhiza, C. aromatica, C. amada, and C. zedoaria. The antioxidant activity was determined using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity, oxygen radical absorbance capacity (ORAC), reducing power and 2-deoxyribose (2-DR) oxidation assay. Our results suggested that RD contained significantly higher concentrations of total phenolic (157.4 mg gallic acid equivalent/g extract) and flavonoids (1089.5 mg rutin equivalent/g extract). RD also showed significantly higher DPPH radical-scavenging activity (IC50: 26.4 μg/mL), ORAC (14,090 μmol Trolox equivalent/g extract), reducing power absorbance (0.33) and hydroxyl radical scavenging activity (IC50: 7.4 μg/mL). Therefore, RD was chosen for the isolation of antioxidant compounds using silica gel column, Toyopearl HW-40F column, and high-performance liquid chromatography. Structural identification of the compounds was conducted using 1H NMR, 13C NMR, and liquid chromatography-tandem mass spectrometry. The purified antioxidant compounds were bisabolone-9-one (1), 4-methyllene-5-hydroxybisabola-2,10-diene-9-one (2), turmeronol B (3), 5-hydroxy-1,7-bis(4-hydroxy-3-methoxyphenyl)-1-hepten-3-one (4), 3-hydroxy-1,7-bis(4-hydroxyphenyl)-6-hepten-1,5-dione (5), cyclobisdemethoxycurcumin (6), bisdemethoxycurcumin (7), demethoxycurcumin (8) and curcumin (9). The IC50 for DPPH radical-scavenging activity were 474, 621, 234, 29, 39, 257, 198, 47 and 18 μM and hydroxyl radical-scavenging activity were 25.1, 24.4, 20.2, 2.1, 5.1, 17.2, 7.2, 3.3 and 1.5 μM for compound 1, 2, 3, 4, 5, 6, 7, 8 and 9, respectively. Our findings suggested that the RD variety of C. longa, developed by the University of the Ryukyus, Okinawa, Japan, is a promising source of natural antioxidants.