Competitive ability of some cover crop species against Asystasia gangetica and Pennisetum polystachion

Abstract

Asystasia gangetica and Pennisetum polystachion are the most troublesome weeds in oil palm plantations in Malaysia and establishment of cover crops under oil palms is an integral part of sustainable weed management in plantations. Replacement-series experiments were conducted to evaluate the mode and strength of competitiveness of four legume cover crop species, Calopogonium caeruleum, Centrosema pubescens, Mucuna bracteata and Pueraria javanica, and one soft grass species, Axonopus compressus, against Asystasia gangetica and Pennisetum polystachion. Relative yield, relative yield total and relative crowding coefficient were calculated with reference to shoot biomass. Asystasia gangetica was a consistently weaker competitor than Pennisetum polystachion. The legume cover crop species had higher relative yield when grown in mixtures, whereas the yield of Asystasia gangetica was lower in mixtures with legumes than in monoculture. The higher competitiveness of legumes was due to greater canopy height and leaf area index. Centrosema pubescens was a slightly weaker competitor than the other legumes. Although leaf area per plant of Centrosema pubescens did not differ from that of other three legumes, canopy height and blocking photosynthetically active radiation to the soil surface were lower. When grown with a cover crop for 12 weeks, dry weight per plant, leaf area and shoot number of Pennisetum polystachion increased as its proportion decreased in mixtures. Relative yield data indicated that Pennisetum polystachion is a strong competitor. Axonopus compressus was less susceptible to Pennisetum polystachion interference than the legumes. All cover crop species studied proved highly competitive against Asystasia gangetica, but none could compete against Pennisetum polystachion. The study confirms the feasibility of using a cover crop for management of Asystasia gangetica.     

Timber species grouping in Bangladesh: linking wood properties

Timber species grouping (TSG) is essential for meaningful and cost-optimal use of wood. Bangladesh forests are exceedingly diverse and comprise many woody species which are potentially suitable for versatile uses including structural materials. Traditionally, widely known tree species are used for structural timber because technological properties of most of the species are poorly known. In this study, a hierarchical agglomerative cluster analysis based on three selected wood properties [i.e., wood density, modulus of elasticity (MOE) and modulus of rupture (MOR)] of seventy-nine timber species was done. The clustering process led to the formation of four distinct species groups [i.e., very low (TSG1), low (TSG2), medium (TSG3) and high (TSG4)]. However, the species grouping patterns also varied from trait to trait. This might be due to moderate relationship between density and MOE (r ² = 0.46) or MOR (r ² = 0.52). Species of the TSG1 group are mainly characterized by extremely low trait values, while the TSG4 group consists of species having exceedingly high trait values. The TSG2 and TSG3 groups are characterized by low and medium trait values. Hence, it is suggested to select suitable species from these groups, particularly the lesser known high-quality species in afforestation and reforestation programs to meet future timber demand in Bangladesh.     

Potentiality for value-added technical use of Indian sisal

India is one of the major exporters of sisal ropes and cordages but the raw fibres are imported from Africa and some other places. Import of sisal fibre in India is increasing at the rate of 25% per year for last few years. Sisal is grown in randomly distributed pockets all over Indian sub-continent mainly for some other purpose without giving any attention to the selective variety or species of Agave family. It is commonly stated that quality of Indian sisal fibre is not up to the mark of making standard quality of ropes, binder, twines, etc. The paper reports the textile related structure and properties (viz. tensile behavior, bending rigidity, thickness, coefficient of friction, moisture, thickness, surface appearance, transversal structure) of Indian variety of sisal fibres grown in two different agro-climatic regions in India to find out its suitability for producing standard quality products. The properties of Indian sisal fibres have also been compared to the imported one to explore the potentiality of the Indian fibres for making standard international quality products. The present work reveals that it is possible to grow sisal fibre of specified variety/species (Agave sisalana) having much balanced property parameters for producing international quality products (viz., ropes, cordages agricultural binders). Agave sisalana grown in certain agro-climatic regions (viz., Orissa) in India showed much comparable property parameters, even sometimes better, to the fibres imported from Tanzania.     

Demographics of patients with surgical and nonsurgical cystic echinococcosis in East Azerbaijan from 2001 to 2012

Echinococcosis is very frequent helminthic infection in human being. The disease is endemic in Iran and particularly in its northwestern region, East Azerbaijan. The objective of this study was to study demographics of patients with cystic echinococcosis in East Azerbaijan; as well as to repot the sites of involvements. In this cross-sectional study, 318 patients with surgical and nonsurgical cystic echinococcosis were recruited from three referral centers in Tabriz within a 10-year period of time. The patients' demographics (age and gender) and the site of infection were investigated. Among the patients, females were predominant (57.5 vs. 42.5%). The mean age of patients was 32.59 +/- 18.47 (range: < 1-87) years and the most frequently age group was 20-30 years (23.6%), followed by the age groups of 30-40 years (21.7%), 10-20 years (14.2%), 40-50 years (11.9%), 50-60 years (11.3%), < 1 year (6%), 60-70 years (4.7%), 1-10 years (4.1%) and finally, > 70 years (2.5%). The lung was the most frequently infected organ (48.1%), followed by the liver (28.9%), gallbladder (3.5%), spleen and kidney (each one in 2.2%), abdomen, intestine, pleura, bronchus and mediastinum (each one in 1.6%), chest wall and heart (each one in 1.3%), brain, pericardium, facial sinus, pancreas and esophagus (each one in 0.6%) and the ovary, uterus, axillary region, pelvis and femur (each one in 0.3%). In conclusion, this study showed that the patients with hydatid cysts in East Azerbaijan Province are mainly females in the age group of 20-40 years. The lung and liver are the major sites of infection in these patients.     

Methyl donors potentiates growth, metabolic status and neurotransmitter enzyme in Labeo rohita fingerlings exposed to endosulfan and temperature

A 2-month preliminary study was conducted to delineate the effect of dietary methyl donors (choline, betaine, and lecithin) on the growth performance and metabolic status of Labeo rohita fingerlings subjected to endosulfan alone and in combination with elevated temperature. Four iso-caloric and iso-nitrogenous diets viz. basal diet, betaine-supplemented diet, choline-supplemented diet and lecithin-supplemented diet were prepared and fed to the different experimental groups throughout the experimental period as per the design. Two hundred and seventy fingerlings (average weight 7.95?±?0.04?g) were randomly distributed in six treatment groups each having three replicates. The experimental groups were as follows: fish subjected to normal water (without endosulfan) and fed with control diet (control group T(0)), fish subjected to endosulfan-treated water and fed with control diet (T(1)), fish subjected to concurrent exposure of endosulfan and elevated temperature and fed with control diet (T(2)), fish subjected to endosulfan and elevated temperature and fed with choline-supplemented diet (T(3)), fish subjected to endosulfan and temperature and fed with betaine-supplemented feed (T(4)), and fish subjected to endosulfan and temperature and fed with lecithin-supplemented feed (T(5)). The result shows that in both the groups, that is, endosulfan exposed and concurrent exposure to endosulfan and elevated temperature group of L. rohita the growth performance like percentage weight gain, feed conversion ratio and specific growth rates were significantly different (P?相似文献   

Genetics and biology of cytoplasmic male sterility and its applications in forage and turf grass breeding

Hybrid breeding can exploit heterosis and thus offers opportunities to maximize yield, quality and resistance traits in crop species. Cytoplasmic male sterility (CMS) is a widely applied tool for efficient hybrid seed production. Encoded in the mitochondrial genome, CMS is maternally inherited, and thus, it can be challenging to apply in breeding schemes of allogamous self‐incompatible plant species, such as perennial ryegrass. Starting with a general introduction to the origin and the function of mitochondria in plants, this review focuses on the genetics and biology of CMS systems in plants to identify conserved and system‐specific mechanisms. We examine prospects of comparative mitochondrial genomics to identify candidate genes and causative polymorphisms associated with CMS across species and discuss specificities, obstacles and potentials of CMS as a breeding tool for maximizing heterosis in forage grasses. The purpose of the review is to highlight the importance of CMS and hybrid breeding in grasses, with the aim of facilitating research and development of novel breeding strategies to address the future needs for food, feed and biomass production.     

Preparation of selective ion adsorbent by photo curing with acrylic and phosphoric acid on jute yarn

Jute yarns were cured with acrylic acid (AA) and phosphoric acid (PA) using UV radiation in order to prepare selective ion adsorbent. A series of formulations were prepared in methanol containing varying percentages of (10–70 %) of AA and 2 % photo-initiator (PI) (Darocur-4043). jute yarns were soaked in this formulation for various soaking times (10–30 min) and cured under UV radiation of different intensities (20–50 UV passes). Concentration of AA, soaking time and intensity of UV radiation were optimized based on polymer loading (PL). The maximum PL (21 %) was observed for 50 % AA solution for 20 min soaking time at 40 UV passes. Various formulations were prepared using 5–15 % (w/w) of phosphoric acid, 50 % AA and 2 % PI in methanol. Then jute yarns were soaked in this solution for 20 min and irradiated at 40th UV pass. The concentration of PA was again optimized for maximum PL. It was found that the formulation containing 10 % PA, 50 % AA, 38 % methanol and 2 % PI showed 70.95 % of PL. To investigate the adsorbent behavior, a 10 ppm CuSO₄ solution was prepared and then grafted yarns were soaked in the solutions for 30–300 min at different conditions. After withdrawing the yarns, the remaining copper in the solution were measured by atomic absorption spectrophotometer (AAS). It was revealed that copper was successfully removed by using the grafted jute yarns.