The estimated value of the worldwide sales of plant-based medicines exceeds $15 billion in the year 2004. The international trade of plant-based medicines is becoming a major strength in the global economy and the demand is increasing in both developing and industrialized nations. However, the explosive growth of the trade of plant-based medicines has been accompanied by issues of quality, consistency and efficacy and leading to serious health problems associated with traditional field-grown plants or wild-harvest. This article discusses the problems associated with the cultivation, harvesting and process of medicinal plants for the production of phyto-pharmaceuticals. We suggest that it is necessary to ensure the safety and efficacy of plant-based medicines and to protect the genetic diversity of medicinal plants. An alternative is the cultivation of medicinal plants under controlled environments, which allows the precise control of optimized environmental conditions with maximum biomass and medicinal metabolites production and ensures the plants free from biotic and abiotic contaminations with consistent biochemical profiles. The controlled environment technology also ensures application of specific, controlled environment stresses that can optimize the production of medicinal metabolites by inducing natural biochemical changes in plants.
Dormancy and morphological characteristics of the non-harsh tasting line of Japanese bracken (Pteridium aquilinum Kuhn) were investigated. Color of new bud in the harsh-tasting line was pale green, whereas that of the non-harsh tasting line was purplish green. Trichome density of new buds in the non-harsh tasting line was higher and the starting period of bud emergence was about 9 days later than those of the harsh tasting line. To examine the dormancy, the effect of starting time of warming treatment on bud break was investigated. The rhizomes of the nonharsh tasting line grown at an altitude of around 703 m were warmed at minimum temperature of 15°C. Bud break occurred when the treatment was started after November 27. To examine the effect of low temperature on breaking of dormancy, the rhizomes which were harvested on October 30, were treated at either 5 or 10°C. The treated period at each plots were for 10, 20, and 30 days. After low temperature treatment, the rhizomes were warmed at minimum temperature of 16°C. Bud break occurred in the rhizomes only when they were treated by more than 20 days of less than 10°C.
The productivity of rice-wheat cropping has declined in acidic alluvial soils widespread in Bangladesh. Field experiments were conducted for three years at two locations to investigate the effects of 3 levels of lime (0, 1.2 and 2.4 t ha-1) and six combinations of fertilizer treatments on soil pH, nutrient availability, and yields of rice and wheat. Soil pH, available P, exchangeable Ca, and hot-water-extractable B were increased by liming. The levels of Fe and Al content in soil were significantly decreased with lime levels whereas the level of Zn was not affected by lime levels. Boron availability enhanced by liming could have significant effect in preventing spikesterility and thereby increased the yield of wheat. The yield response of crops revealed that combination of full dose of liming (2.4 t ha-1) with N, P, K and S applications at the rates of 100, 40, 40 and 20 kg ha-1 in both the crops and 5 kg ha-1 of Zn only in rice are preferable to obtain higher yield in acidic alluvial soil. Mg and B were not required to apply as fertilizer at least for 3 years in such a soil treated with full dose of lime.
We evaluated the use of pumice as a substrate for hydroponics of muskmelon. Overflows were made 0.0 cm, 2.5 cm, or 5.0 cm from internal bottom of bed to adjust the depth of nutrient solution in the bottom of bed (water level) . In 5.0 cm treatment, hermaphrodite flowers bloomed about 2 days earlier than in the other treatments. Soluble solids content of the fruits was about 15% in all treatments, but citric acid concent was significantly higher in 2.5 cm treatment than in 0.0 cm treatment with an associated decrease in solid-acid ratio. P, Ca, Mg and Mn contents of the fruits were maximum in 2.5 cm treatment, with P and Ca contents being significantly higher than those in 5.0 cm treatment, but K content was the highest in 5.0 cm treatment. Since growth of the plants was satisfactory and size and soluble solids content of the fruits were adequate at over 2.5 cm from internal bottom of bed, pumice is considered to be useful in hydroponics of muskmelon. Analysis of mineral elements in the drain indicated the marked decrease in P content in fruit developing period and excessive increase of EC in late stage of cultivation.
The effects of massive sediment dredging on water quality, trophic status and on bottom sediment characteristics of three lakes of Udaipur (India) was studied for a period of five years. The lakes (Fateh Sagar, Baghdara and Udai Sagar) differ with respect to the nature and magnitude of anthropogenic perturbations. During dry periods (May-June, 2001; May-June, 2003; April-June, 2004), about 4, 205.6 and 2, 147.1 tons of bottom sediments were removed from Udai Sagar and Fateh Sagar respectively. During the course of study (from Year 2000 to 2004), N and P concentrations declined significantly both in sediment and in water column of Fateh Sagar and Udai Sagar. The declining nutrient concentration caused reduction in chlorophyll biomass (up to 41.4%) and primary productivity (up to 32.2%) reflecting a reversal of trophic status towards oligotrophy. A comparison with Baghdara further indicate that sediment removal have strong influence on water chemistry and trophic status of Fateh Sagar and Udai Sagar. We suggest that the sediment dredging which help reversing trophic status may be used as an effective tool for restoration of freshwater tropical shallow lakes.
The combined effects of water and light on net photosynthesis (A) of rooted cuttings of lemon (Citrus limon L. Burm.f. Eureka) were investigated to determine if the effects of water stress and shading are interactive. Treatments investigated included sufficient water +full light (control), water stress + full light, sufficient water + shade and water stress + shade. Under ambient conditions, the main effects of water stress significantly decreased A, gs, and chlorophyll content. It increased Ci. Mean effects of shading decreased A and NPQ. It significantly increased Fm, and Fv/Fm. Water×light interactions were not significant for A, gs, Ci, chlorophyll content, Fo, FvFm, qP and NPQ. But they were significant for Fm, and Yield. Under controlled environment, the mean effects of water stress on A were as for ambient conditions, but the effects of shade were reversed. Water×light interactions significantly influenced A at irradiance of 50 and 300μmol m-2 s-1 but not at 600 μmol m-2 s-1. At 300 μmol m-2 s-1, shaded sufficiently watered plants had significantly higher A than plants grown under the other water×light combinations. Water stressed plants grown in full light were photoinhibited at 50-600μmol m-2 s-1. Water stress and shading effects on A are interactive if leaf environment is controlled.
Effects of anoxia on the levels of free-amino acids were investigated in the coleoptiles of rice (Oryza sativa L.) seedlings. Rice coleoptiles are able to grow in extremely low oxygen condition. Anoxic stress increased the concentration of total free-amino acids in the coleoptiles. After 48 h, alanine (Ala) and γ-aminobutyric acid (Gaba) in anoxic coleoptiles were 2.7- and 10.6-fold greater than those in non-stressed coleoptiles, respectively. Ala and Gaba represented 40% of the amino acid pool in anoxic coleoptiles. These anoxic-induced amino acids may allow rice coleoptiles to make biochemical adjustment that enable them to cope with the stress condition.
Nickel (Ni) electrodes were placed in a culture solution to release Ni, a component of urease. The growth of spinach (Spinacia oleracea L.) cultured in nutrient solutions containing urea (U solution) with Ni electrodes was superior to that cultured in nutrient solutions without electrodes; the best growth was observed when the nutrient concentration was 1 unit and a 3 μA current was applied. Urease activity of spinach leaves was higher in the U solution with Ni electrodes, and the activity that occurred 4 weeks after planting was the highest when 3 μA current was applied to Ni electrodes. The application of electric current to Ni electrodes in the U solution increased the urease activity and promoted the conversion of urea to ammonia, thereby promoting the growth of spinach.
Tomato (Lycopersicon esculentum Mill.) fruit production depends on the accumulation of mass (i.e., water, sugar, calcium ion, etc.) in the fruit via phloem and xylem transport. Water accumulation in the fruit is responsible for the fruit expansion growth, that is variable according to the balance between sap flux into the fruit via vascular system and transpiratory water loss from the fruit. Sugar accumulation in the fruit depends on translocation of photoassimilates from leaves through phloem. Salt or water stress treatment in the tomato fruit production is generally provided during the reproductive stage in order to obtain high quality fruits. This treatment leads to the increment of fruit sugar concentration, the restriction of fruit expansion growth and the increase in blossom-end rot. In a previous study on tomato fruit production, analyses of fruit parameters, such as dry matter weight, fresh weight, nutrients, etc., have been carried out using harvested fruits at the intervals of one week or 10 days. However, it is important to demonstrate the dynamics of sap flux with reference to mass accumulation in the fruit. Therefore, three new measurement systems or methods to evaluate the dynamics of mass accumulation in the fruit were developed, and the effects of day-night temperature, water stress, and salt stress on fruit growth and fruit water balance were analyzed.