Traditional utilization of wild date palm （Phoenix sylvestris） in rural Bangladesh： an approach to sustainable biodiversity management

A study was conducted to explore the traditional utilization pattern and indigenous management practices of wild date palm （Phoenix sylvestris Roxb） in the rural agrarian regions of Bangladesh. A multistage sampling method with 10% intensity and a semi-structured questionnaire were used for the study. The farmers manage the palm mainly for sap production with which sugar based secondary goods are manufactured. The sap is either used fresh as drink or after some sort of processing as molasses and/or alcoholic beverage. Seven diversified sites support the palm as its habitat and most palms （20.40%） occur in orchards. Besides growing naturally, the palm is also established in orchards using the wildings as the staple planting material. Although the medium category farmers own most of the palms （33%）, a considerable portion （28.68%） of it is managed by the landless farmers, who earn a substantial livelihood from the palms. The farmers practice their own indigenous wisdom in every stage of the palm＇s maintenance from planting through tapping for sap collec- tion to the processing of products. If managed more scientifically on a sustainable basis with the collaboration of farmers＇ indigenou~ knowledge, this familiar palm could be able to support the rural economy of the country to a great extent. Side by side, it would also be able to contribute to the richness of biodiversity in the region.     

Cadmium Phytoextraction Efficiency of Arum (Colocasia antiquorum), Radish (Raphanus sativus L.) and Water Spinach (Ipomoea aquatica) Grown in Hydroponics

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.     

Sensing and Uptake of Nitrogen in Rice Plant: A Molecular View

As a main feature of plant autotrophy, assimilation of inorganic nitrogen(N) is not only of fundamental interest to the crop, but also a crucial factor in crop productivity. N is the main plant mineral nutrient needed for chlorophyll production and other plant cell components(proteins, nucleic acids and amino acids). I highlighted the novel aspects of N responsive sensors, transporters and signaling molecules recently identified in the monocot rice plant, and discussed their potential roles in N sensing and transporting. Furthermore, over the last couple of years, N sensing has been shown to be affected by different external factors, which act as local signals to trigger systemic signaling coordinated by long-distance transport or mobile signals in plant body. Understanding of this complex regulatory network provides a foundation mechanism for the development of novel strategies to increase the acquisition and transportation efficiency of nitrogen under varying N conditions for rice production.     

Poor grain filling induced by waterlogging is similar to that in abnormal early ripening in wheat in Western Japan

Abnormal early ripening (AER), a major constraint on wheat production in Western Japan, manifests as sudden leaf senescence shortly after anthesis and results in poor grain filling; this leads to smaller grains and reduced grain yield. It is suggested that overwetting of the soil may be related to AER. We conducted field experiments over 2 seasons (2008-2009 and 2009-2010) in Yamaguchi, Western Japan, with waterlogging treatment using 2 Japanese wheat cultivars, Daichinominori (Western Japanese cultivar) and Haruyutaka (Hokkaido cultivar), which differ in terms of grain growth in the environment of Western Japan. We imposed pre-anthesis waterlogging for 2 weeks in 2008-2009 and post-anthesis waterlogging throughout the grain-filling period in 2009-2010. Pre-anthesis waterlogging had no significant effect on grain yield or grain filling irrespective of cultivar. Post-anthesis waterlogging severely reduced the grain yield by 44% and 36% in Haruyutaka and Daichinominori, respectively. The yield loss was attributable to the smaller grain weight that was a result of slower grain growth rate later in the shortened grain-filling period. Post-anthesis waterlogging induced sudden leaf senescence 1 and 2 weeks after anthesis in Haruyutaka and Daichinominori, respectively, and drastically reduced the photosynthesis and ultimately dry mass accumulation. It also depressed the remobilization of water-soluble carbohydrates (WSCs) from culms to grains leaving more residual WSCs in the culms at harvest (149 and 65 mg g⁻¹ DW in waterlogging and controls, respectively). The results indicate that the reduced grain growth due to waterlogging was attributable to decreased current assimilation and poor remobilization of culm WSCs to grain similar to that in AER plants. These results suggest that injured root function after anthesis might induce early leaf senescence and poor grain filling similar to AER wheat.     

Effect of initial water content on saturated hydraulic conductivity in desalinization with slaking and drying

Soil slaking is an environment-friendly technique that is gaining importance in restoring saline soils. The objective of this article is to evaluate the effect of initial water content (IWC) on saturated hydraulic conductivity (K _s) in desalinization with slaking and drying. Accordingly, a slaking test was carried out during February, 2009 for evaluating the effects of slaking and drying on K _s, sodium adsorption ratio (SAR) and exchangeable sodium percentage (ESP) under various IWC. We prepared natural and air-dried soils of paddy field in Kojima Bay Polder, Japan to give different pre-drying, air-dried, and not dried (natural). The air-dried soils were resaturated. Each soil was well mixed, then dried to different initial moisture contents (60, 50, 40, 30, 20, and 10% by weight). The specimens were immersed into water in the pot for 24 h. The K _s was measured, and cations in slaked and unslaked soils were analyzed. The K _s was high under the water content below 30% in both the natural and the air-dried soils. But the effects were more pronounced in the natural soil. The air-dried soil showed far smaller K _s than the natural soil. In outer solution, the highest SAR was noted at 30% in the natural and 30 and 20% in the air-dried soils. Significant decrease in ESP of the soils (slaked + unslaked) was also observed at the same water content. Lower water content was more effective in decreasing the soil ESP after desalinization from saline soil. The natural soil showed lower ESP and higher porosity, which was considered as a reason for higher K _s of natural soil than that of air-dried soils. The results indicated that lower water content (10–30%) had no hazardous effect on K _s by slaking and drying of soil.     

Small-Scale Mehedi (<Emphasis Type="Italic">Lawsonia inermis</Emphasis> L.) Farming in the Central Bangladesh: A Promising NTFP-Based Rural Livelihood Outside the Forests

Throughout the world ornamentation of body with mehedi (Lawsonia inermis L.) leaf paste, with the trade name ‘henna body art’ is becoming increasingly popular. The worldwide increasing demand of mehedi leaf encourages many countries to adopt commercial farming of the plant. Farmers living in central Bangladesh recently commenced small-scale mehedi farming, primarily with the purpose of meeting national demand. A total of 182 farmers are engaged in mehedi farming and a study was conducted among 36 of them (a 20% random sample) to explore indigenous management techniques, marketing, livelihood potential and constraints of the enterprise. Farming was reported to be the major primary occupation of the study area. An average of 0.05 ha land of the respondents was used for mehedi cultivation, which constituted 16.7% of their average farm land. The farmers applied their own indigenous technology in every aspect of the farming, using branch cuttings as the only propagation material. The financial analysis indicated that mehedi farming is a profitable and attractive option for rural livelihoods [with an estimated net present value of Tk (Bangladeshi currency unit, 1 US $ = 68 Taka (as of May, 2009).) 179,500 for 0.1 ha plantation]. However, the enterprise faces several constraints, including absence of a nursery for supplying planting materials, storage and effective marketing facilities, available capital for investment, improved technology, and above all, government support. If the government extends cooperation by assisting farmers with training, technology, credit and market development, mehedi farming could become an important revenue-earning enterprise in the small-scale cottage sector of Bangladesh.     

Characterization of plant and animal based natural fibers reinforced polypropylene composites and their comparative study

Natural fibers are largely divided into two categories depending on their origin: plant based and animal based. Plant based natural jute fiber reinforced polypropylene (PP) matrix composites (20 wt% fiber) were fabricated by compression molding. Bending strength (BS), bending modulus (BM), tensile strength (TS), Young’s modulus (YM), and impact strength (IS) of the composites were found 44.2 MPa, 2200 MPa, 41.3 MPa, 750 MPa and 12 kJ/m², respectively. Animal based natural B. mori silk fiber reinforced polypropylene (PP) matrix composites (20 wt% fiber) were fabricated in the same way and the mechanical properties were compared over the silk based composites. TS, YM, BS, BM, IS of silk fiber reinforced polypropylene composites were found 55.6 MPa, 760 MPa, 57.1 MPa, 3320 MPa and 17 kJ/m² respectively. Degradation of composites in soil was measured upto twelve weeks. It was found that plant based jute fiber/PP composite losses its strength more than animal based silk fiber/PP composite for the same period of time. The comparative study makes it clear that mechanical properties of silk/PP composites are greater than those values of jute/PP composites. But jute/PP composites are more degradable than silk/PP composites i.e., silk/PP composites retain their strength for a longer period than jute/PP composites.     

Vertical transmission of sublethal granulovirus infection in the tobacco caterpillar <Emphasis Type="Italic">Spodoptera litura</Emphasis>

Larvae that survived sublethal infection of Spodoptera litura granulovirus (SlGV) as 4th and 5th instars led to an increase in the larval period of treated larvae when compared with control. While pupal period and pupal weight remained unaffected, a significant alteration in sex ratio was observed. Although survivor moths could mate successfully, there was a significant reduction in the proportion of ovipositing females in treated larvae as compared with control. A significant reduction in fecundity of moths emerging from treated larvae was also noticed, but the egg viability was never influenced by the treatment. However, there was a significant increase in progeny mortality in treated larvae over control. The offspring mortality in survivors increased up to three subsequent generations but not thereafter. Hence, repeated field applications of inoculum are required. The implication of the present findings in terms of reduced fecundity coupled with increased larval development indicates that vertical transmission can lead to increased virus dispersal, both of which would reduce the host's innate capacity for population increase. This is particularly important in S. litura, which is a migratory species and occurs sporadically in a particular agro-ecosystem.     

Polyphosphate kinase is essential for swarming motility, tolerance to environmental stresses, and virulence in Pseudomonas syringae pv. tabaci 6605

Polyphosphate kinase (PPK), encoded by the ppk gene, is a principal enzyme responsible for synthesis of inorganic polyphosphate (poly P) from ATP in many Gram-negative bacteria. In order to elucidate the functions of poly P in Pseudomonas syringae pv. tabaci 6605, an in-frame deletion mutant of the ppk gene (ppk) was constructed. The ppk mutant did not accumulate poly P, whereas the wild-type strain accumulated a large quantity. The mutant had reduced swarming motility, even though it retains swimming motility like the parental strain. The mutant exhibited increased sensitivity to prolonged incubation and environmental stresses, such as heat shock and oxidative stress and reduced exopolysaccharide (EPS) production compared to the wild-type. Northern blot analysis revealed that expression of the rpoS gene, encoding the stationary phase sigma factor RpoS, was reduced in ppk in the logarithmic phase, indicating that rpoS is regulated by the ppk gene. The poly P deficient mutant had significantly reduced ability to cause disease in its host tobacco plant and in planta growth of the mutant was also significantly reduced in host tobacco leaves as compared to the wild-type strain. Thus, our results suggest that poly P plays an important role in the virulence of P. syringae pv. tabaci 6605.