Growth and Nutrient Accumulation of Winged Bean and Velvet Bean as Cover Crops in a Subtropical Region     

《Plant Production Science》2013,16(4):360-366

We examined biomass dry matter and nutrient uptake of live plant parts, leaf area index, and litter of winged bean (Psophocarpus tetragonolobus) and velvet bean (Mucuna pruriens) 12, 18, 24 and 30 weeks after sowing (WAS). The two plants had similar leaf and stem+petiole biomasses. At 30 WAS winged bean had a significantly lower pod yield than velvet bean. Between 18 and 30 WAS, winged bean produced less litter than velvet bean due to differences in growth stages. The total mulch of live parts and litter of winged bean and velvet bean completely covered the ground by 18 and 12 WAS, respectively. Compared to velvet bean, the leaf and stem+petiole of winged bean had a significantly higher N concentration; significantly higher N uptake at 24 and 30 WAS; significantly lower C/N ratio; and significantly higher P, K and Mg concentrations. In winged bean, P uptake was significantly higher in the leaf at 30 WAS and in the stem+petiole at all harvesting times. The total biomass of the leaf, stem+petiole and litter of winged bean was 317–561 g DM m-², and their N content was 12.3–17.7 g m-². The total biomass of live parts and litter of winged bean might be sufficient to suppress weeds and increase soil N. Winged bean is an appropriate legume cover crop and green manure due to its longer growing period and superior ground-covering ability and high N input.  相似文献   

Obituaries     

D.M. Scotney 《African Journal of Range and Forage Science》2013,30(1):10-11

Uittreksel

Die groeifunksies benodig vir die simulasie van produksie van ‘n Themeda triandra‐grasveld met behulp van die PUTU 11 simulasiemodel is ontwikkel. Vir die ontwikkeling van die model is die veldproduksiedata van die 1980/81 groeiseisoen gebruik waarna dit suksesvol, vir drie groeiseisoene met uiteenlopende klimaatstoestande, getoets is. In die model is koolhidraatverdeling tussen verskillende plantdele gesimuleer deur van verskillende funksies vir elke groeistadium gebruik te maak. Die hipotese is gestel dat die verskillende plantdele na ‘ n gewenste massaverhouding tot die totale plantmassa streef deur die translokasie van koolhidrate. ‘n Beperkte maksimum tempo van translokasie in en uit plantdele is gestel. Die werklike translokasietempo verander sigmoidaal met die relatiewe massaverhoudingafwyking.  相似文献   

First report of Wolbachia from field populations of Culex mosquitoes in south-western Nigeria     

《African Zoology》2013,48(3):181-185

Recent reports on finding Wolbachia-strain infections in field mosquito species in some West African countries and the potential for developing these as disease vector biocontrol tools have prompted a search for Wolbachia in mosquitoes within the study area. Using a completely randomised design, mosquito traps were set at different locations in a rural and an urbanised community. One hundred and eighty (180) mosquitoes were trapped and pooled on the basis of genus, sex and site of collection, because there have been no earlier reports of Wolbachia isolated from Nigeria. Twenty pools, made up of not more than ten mosquitoes per pool, were homogenised and analysed for Wolbachia-specific DNA. Mosquitoes were trapped within Ede (urbanised community) and Akoda (rural community). Genomic DNA was extracted from trapped mosquito samples and used as a template in a PCR reaction. The Wolbachia sp. specific 16S rRNA gene was amplified, sequence analysis of PCR products was performed and a chromatogram of the sequence was subjected to Basic Local Alignment Search Tool analysis to identify the Wolbachia sp. This sequence was subsequently submitted to GenBank with accession number MK127541. The first evidence of the presence of the endosymbiont, Wolbachia in field-caught mosquitoes is hereby documented. The homology of this strain of Wolbachia bears similarities to those reported recently from other parts of West Africa and forms a single clade with a Wolbachia sp. from Mali, with a strong bootstrap support of 99%. This finding of a Wolbachia strain in mosquitoes at Ede could form the basis for more searches for diverse strains of Wolbachia in Nigeria.  相似文献   

Anthropogenic Influences on Wild Nutmeg Fruit Crop in the Western Ghats of India     

Manju V. Sharma  Catherine M. Collins  Simon R. Leather 《Journal of Sustainable Forestry》2013,32(6):563-575

Myristica dactyloides is characteristic of the mid- and high-elevation evergreen forests of the Western Ghats of India. Aril and seeds of the species are valuable nontimber forest products and are harvested extensively. We made visual estimates of fruit crop size in nine populations. We assessed disturbance using five variables: distance from road, method of harvesting fruits, nonforest matrix around the population, seedling regeneration, and protected area status. Unsustainable harvest and proximity to road impacted fruit crop, as did the nonforest matrix (F = 38.17 df = 5,102, p < .001). While high protection and measures against harvesting keep some populations safe, the harvest method plays a crucial role in determining total fruit production and seedling recruitment in the species.  相似文献   

论酒泉市农作物秸秆资源饲料化利用的现实与前景     

张立萍 《畜牧兽医杂志》2013,32(5):40-42

农作物秸秆资源具有重要的饲料价值,该文以酒泉市秸秆饲料化利用为切入点,探究农作物秸秆饲料化利用前景,为酒泉市构建生态循环农业和资源节约型社会提供新的视角和思路。  相似文献   

Soil Salinity in South India: Problems and Solutions     

《Journal of Crop Improvement》2013,27(1-2):247-275

SUMMARY

Soil salinity is assuming menacing proportions for production of agricultural and horticultural crops in South India. South India comprises of Andhra Pradesh (AP), Tamil Nadu (TN), Karnataka, Kerala, Goa, and Islands in Bay of Bengal (Andaman and Nicobar) and Arabian Sea (Lakshadweep). It comprises central uplands, Deccan plateau (Karnataka plateau and Telangana plateau of AP), Nilgiri hills of TN, South Sahiailri, Eastern hills (Eastern Ghats, TN, upland) and Coastal Plains. The rainfall ranges from 400 to 500 mm in AP, 450 to 1300 mm in Karnataka, 500 to 1215 mm in TN, 100 to 450 mm in Kerala. Climate is mainly semi-arid in nature. Red soils (Alfisols, Inceptisols, and Entisols) make up about 60–65% and are well drained, blacksoils (Vertisols and Inceptisols) comprise about 20–25% and the rest are coastal sands. Soil salinity problems are encountered in almost all the districts in Karnataka and AP. The area extends to about 0.176 million ha in AP, 0.2 million ha in Karnataka, 0.0427 million ha in TN and about 0.03 million ha in Kerala. Introduction of canal irrigation water and use of underground saline waters accelerated the appearance of salt affected soils. Soil salinity observed in South India ranges from hydrometphic saline soils in Kerala to highly saline (EC 20–30 dS m^?1) in Karnataka and AP. Saline soils were classified in to Natrargids or Solarthrids at subgroup level depending on the occurance of nitric or salic horizon within few centimetres of the surface. Soil salinity has reduced crop yields upto 50% and consequently cropping has been abandoned in many areas. Excess soluble salts can be removed through scrapping the surface salt crust or flushing and leaching or through subsurface drainage depending on the problem. Crops also vary in their ability to tolerate salinity at different stages of growth. In most crops subjected to irrigations with saline waters, germination and early seedling stages are generally the most sensitive and their tolerance increases with age. Salt tolerant varieties and nutrient management of crops in saline soils are important solutions for crop production under saline soils.  相似文献   

Advances in the Design of Resource-Efficient Cropping Systems     

《Journal of Crop Improvement》2013,27(1-2):15-32

SUMMARY

Cropping systems in the Midwest USA are evolving as farmers seek labor-efficient designs to capture and use available light and precipitation. Heavy reliance on fossil fuels and other energy-intensive production inputs coupled with uncertain markets for commodities have encouraged the search for greater energy efficiency as well as alternative crops, markets, and production systems. Agroecology has emerged as an innovative and integrative approach to evaluating systems more suited to the often harsh and unpredictable environment, using native prairie structure and function as one guide to design of future systems. A more specific approach, Natural Systems Agriculture, is being explored as a new paradigm to saving soil while producing the crop and animal output needed for a growing global population. Whole-farm and landscape-level design and planning will become more important as society recognizes and values multifunctional rural landscapes.  相似文献   

Improving Soil Quality     

《Journal of Crop Improvement》2013,27(1):95-121

Abstract

Future advancements in crop production will rely on increased understanding of ecological principles that control interactions among cropping system components. Our interest in linking soil quality and weed management derives from the belief that greater understanding of key processes and properties that define soil-weed relationships will lead to the design of agroecosystems with greater capacity and opportunity to suppress weeds. We identified seed-bank persistence, seedling establishment, and interspecific interference as key processes that affect annual weed population dynamics. We then examined how soil processes and properties can affect each of these factors and how, in turn, soil-improving management practices and cropping system design may affect weed dynamics. We established weed-related soil management objectives as: (i) reducing the persistence of seeds in the soil; (ii) reducing the abundance of safe-sites for weed establishment and the filling of available sites; and (iii) reducing crop yield loss caused by a given density of weeds. Soil factors that can be managed to achieve these goals include: (i) chemical, physical, and biological conditions that affect resources required for weed seed germination, establishment and growth; (ii) habitat for herbivores and pathogens that attack weed seeds and seedlings; and (iii) phytotoxin production. We concluded that many as yet unexplored opportunities exist to manipulate the soil environment and to design cropping systems that create multiple weed suppressive conditions at critical junctures of weed seed-bank persistence, establishment, and interference.  相似文献   

Allelopathy and Its Implications in Agroecosystems     

《Journal of Crop Improvement》2013,27(1):169-202

Summary

Allelopathy includes both positive and negative effects of one plant on the other through environment, though most of the studies seem to focus on its deleterious impacts. It plays a key role in both natural and managed ecosystems. In agroecosystems, several weeds, crops, agroforestry trees and fruit trees have been shown to exert allelopathic influence on the crops, thus, affecting their germination and growth adversely. Some of the agricultural and horticultural crops affect their own seedlings grown in succession which is commonly known as replant problem/syndrome. Available studies indicate that allelochemicals act via bringing certain changes in physiological functions like respiration, photosynthesis and ion uptake. These, in turn, result in visible changes in seed germination, further growth reduction and overall performance of the target plants. The studies on interplant interactions assume significance in agroforestry programmes for selecting the types of crops complementary to the selective tree species. In the recent past, however, scientific attention has also been drawn to exploit the positive significant roles this phenomenon can play in enhancing crop productivity. In this context, we discuss the tremendous scope of allelopathy towards weed and pest management, apart from nitrogen conservation, and synthesis of novel agrochemicals based on natural product chemistry. The use of natural products of plant or microbial origin as pesticides/herbicides have gained much attention of the scientists as they offer many advantages over synthetic chemicals. The production of such chemicals should be enhanced by devising suitable protocols based on biotechnological procedures for their widespread utilization.  相似文献   

Enhancing Productivity of Rice-Wheat System Through Integrated Crop Management in the Eastern-Gangetic Plains of South Asia     

《Journal of Crop Improvement》2013,27(1):147-170

Abstract

Rice (Oryza sariva)-wheat (Triticum aestivum) rotation is the major production system in the Indo-Gangetic plains of South Asia and mid hills and is important for the food security of the region. The productivity and profitability of the rice-wheat system are very low mainly because of inappropriate nutrient input and poor crop management practices. Field experiments were conducted in 21 farmers' fields in Bara and Parsa districts in the Eastern-Gangetic plains of Nepal from May 1999 to April 2002 to evaluate site-specific nutrient management (SSNM) and integrated crop management (ICM) for improving rice-wheat productivity and profitability. Soil nutrient-supplying capacity (based on omission plot method) varied largely among farmers' fields. Rice soil had a higher N, P, and K-supplying capacity (35–76, 8–17, and 63–98 kg ha¹, compared with wheat (16–41, 6–12, and 20–104 kg ha¹, respectively). Both SSNM and ICM strategies significantly improved the grain yields of rice and wheat. Overall yield increment by ICM over farmers' practice (FP) reached up to 2.3 Mg ha¹ (66%) in rice and 2.3 Mg ha¹ (87%) in wheat, suggesting that there is a large potential for increasing rice and wheat yields in Nepal. Yield gap 1 (maximum attainable yieldaverage yield in ICM) was 1.3 to 1.4 Mg ha¹ for rice and 0.3 to 1.0 Mg ha¹ for wheat. While yield gap 2 (maximum attainable yieldaverage yield in FP) ranged from 2.8 to 3.5 Mg ha-1 for rice and 2.3 to 2.8 Mg ha-1 for wheat. Rice N-use efficiencies increased up to 50% and 70% with SSNM and ICM, respectively, over FP. In wheat, N-use efficiency increased up to 46% by ICM over SSNM. The net profit gained by applying ICM over FP was higher in wheat (US$ 217) than in rice (US$ 73). The findings suggest the urgent need to develop an effective program for wider dissemination of ICM technology in the Eastern-Gangetic plains.  相似文献