Spatial configuration becomes more important with increasing habitat loss: a simulation study of environmentally-transmitted parasites     

Tyler R. Bonnell  Ria R. Ghai  Tony L. Goldberg  Raja Sengupta  Colin A. Chapman 《Landscape Ecology》2018,33(8):1259-1272

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Boron Deficiency in Mango (Mangifera indica L.): A Cause Delineation Study in Acidic Soils of Maharashtra, India     

Muthiah Edward Raja  Somanahalli C. Anil Kumar  Sri Y. Raju 《Soil Science and Plant Nutrition》2005,51(5):751-754

Boron deficiency is a major production constraint of Mango cv Alphonso in western coast, Maharashtra, India. The soils are sandy-loam, light, acidic in reaction and receive high annual precipitation of above 2,500 mm. The leaf and soil B status was low with an average of 23 and 0.25 mg kg⁻¹ respectively. About 60% of the orchards were found to be deficient in B. The B adsorption study using Langmuir adsorption isotherm revealed that the adsorption capacity of B by these soils was low with an average adsorption maxima (b) of 16.62 μg g⁻¹ and bonding energy constant ( K ) of 0.09 mL μg⁻¹ making soil B susceptible to leaching. The Mango leaf N status was in excess range, which aggravated B deficiency through growth dilution. A significant negative correlation was observed between leaf B and leaf N (statistically significant at 1% level (p=0.01)). The free Al status of the soils was found to be fairly high, and its detrimental effect on root growth was observed which led to inefficient absorption of limited soil B by roots. The climatic conditions of Konkan like high humidity, high temperature and long sunshine hours also favored widespread incidence of B deficiency, low yield and poor quality. The response of Mango cv Alphonso to the B application was found to be more in foliar than in soil application.  相似文献   

Population dynamics of some coccids (Coccoidea: Hemiptera) infesting sandal (<Emphasis Type="Italic">Santalum album</Emphasis> Linn.) in Bangalore,India     

Ramachandran Sundararaj  Raja Muthukrishnan 《林业研究》2011,22(2):259-262

A study was conducted to investigate the population dynamics of four important coccids viz.,Aonidiella orientalis(Newstead),Ceroplastes actiniformis Green,Cardiococcus bivalvata(Green) and Parasaissetia nigra(Nietner) infesting sandal in Bangalore,India.Meteorological data viz.,monthly mean maximum and minimum temperatures,morning and evening relative humidity and total rainfall were also collected during the experimental period for statistical analysis to ascertain their influence on the population of coccids.The results show that all the four coccids are infesting sandal throughout the year.Maximum temperature exhibited significantly negative correlation with the population dynamics of A.orientalis,while other weather parameters did not show much influence on its incidence.In case of C.bivalvata,minimum temperature and morning relative humidity exhibited significant positive correlation with its population dynamics while other weather parameters had less significant effect on its population dynamics.For C.actiniformis and P.nigra,none of the weather factors seem to have influence on their incidences.  相似文献   

Host range of Alternaria alternata—a potential fungal biocontrol agents for waterhyacinth in India     

R. Mohan Babu  A. Sajeena  K. Seetharaman  P. Vidhyasekaran  P. Rangasamy  M. Som prakash  A. Senthil Raja  K. R. Biji 《Crop Protection》2002,21(10):321-1085

The host ranges of Alternaria alternata and fungi native to India and pathogen of waterhyacinth (Eichhornia crassipes) were evaluated using 29 plant species (some with several cultivars tested) representing 18 families of economic and ecological importance. The results showed that only waterlettuce (Pistia stratiotes), another common weed in India, was infected by A. alternata. The use of these pathogens in the biological control of waterhyacinth would not be expected to affect plants of economic and ecological importance in India.  相似文献   

Harvest timing and N application rate effects on switchgrass yield,nutrient cycling,and partitioning     

Ramdeo Seepaul  K. Raja Reddy  William B. Evans 《Journal of plant nutrition》2017,40(9):1261-1276

Harvest time (HT) and nutrient management may have an effect on switchgrass (Panicum virgatum L.) yield and nutrient cycling. Experimental objectives were to quantify HT and nitrogen (N) rate effects on dry matter yield (DMY), nutrient concentration, and N use. “Alamo” switchgrass was grown under four N rates (0, 40, 80, and 120 kg ha^?1) with six monthly HT (May to October) in a randomized complete block design experiment with a split-plot arrangement. Yield increased cubically and quadratically with HT in Years 1 and 2. Aftermath yield decreased linearly with HT in both years. N rate increased yield in Year 2 only with no yield benefit at rates >40 kg N ha^?1. Nutrient concentration decreased from May to October, while its removal was determined by DMY. N use and recovery were greatest at 40 kg N ha^?1 and declined with additional N inputs. Results indicate that harvesting post-frost-kill produced greater DMY with less nutrient concentration and removal.  相似文献   

Predation by the polyclad flatworm Imogine mediterranea on the cultivated mussel Mytilus galloprovincialis in Bizerta Lagoon (northern Tunisia)          下载免费PDF全文

Mehrez Gammoudi  Raja Ben Ahmed  Nawzet Bouriga  Mossadok Ben‐Attia  Abdel Halim Harrath 《Aquaculture Research》2017,48(4):1608-1617

This study was carried out to investigate a paradigm of predation under natural conditions in Bizerta lagoon. The free‐living marine polyclad flatworm Imogine mediterranea was found to feed on the commercial mussel Mytilus galloprovincialis. Such predation could represent a real threat to mytiliculture at this site. Our field experiments have shown that the mortality of the commercial mussel as a result of active predation by this polyclad is approximately 52% when one polyclad and one prey were placed together in a same experimental container. We found a statistically significant relationship between the size of the polyclad and the extent to which the mussels were disabled or completely eaten. Moreover, in our field experiments, the times required for predation‐caused decreases of populations of the bivalves, that is, LT₁₀, LT₂₅ and LT₅₀, decreased significantly with increases in the size of the polyclad. The time, LT₅₀, required for polyclads to kill half of the bivalve population in field experiments was approximately 4.5 days. A simple disabling (an attack by the polyclad on the adductor muscle of the mussel) was shown to be sufficient to cause irreversible changes leading to mortality. Furthermore, disabling and mortality were found to be linearly correlated. The importance of mucous secretions, pharyngeal type and body musculature in supporting predation by polyclads is discussed. We suggest that measures to control the polyclad pest could incorporate the control of this flatworm's embryonic and postembryonic developmental stages.  相似文献   

EFFECT OF NANOSCALE ZINC OXIDE PARTICLES ON THE GERMINATION,GROWTH AND YIELD OF PEANUT     

T. N. V. K. V. Prasad  P. Sudhakar  Y. Sreenivasulu  P. Latha  V. Munaswamy  K. Raja Reddy 《Journal of plant nutrition》2013,36(6):905-927

An investigation was initiated to examine the effects of nanoscale zinc oxide particles on plant growth and development. In view of the widespread cultivation of peanut in India and in other parts of the globe and in view of the potential influence of zinc on its growth, this plant was chosen as the model system. Peanut seeds were separately treated with different concentrations of nanoscale zinc oxide (ZnO) and chelated bulk zinc sulfate (ZnSO₄) suspensions (a common zinc supplement), respectively and the effect this treatment had on seed germination, seedling vigor, plant growth, flowering, chlorophyll content, pod yield and root growth were studied. Treatment of nanoscale ZnO (25 nm mean particle size) at 1000 ppm concentration promoted both seed germination and seedling vigor and in turn showed early establishment in soil manifested by early flowering and higher leaf chlorophyll content. These particles proved effective in increasing stem and root growth. Pod yield per plant was 34% higher compared to chelated bulk ZnSO₄. Consequently, a field experiment was conducted during Rabi seasons of 2008–2009 and 2009–2010 with the foliar application of nanoscale ZnO particles at 15 times lower dose compared to the chelated ZnSO₄ recommended and we recorded 29.5% and 26.3% higher pod yield, respectively, compared to chelated ZnSO₄. The inhibitory effect with higher nanoparticle concentration (2000 ppm) reveals the need for judicious usage of these particles in such applications. This is the first report on the effect of nanoscale particles on peanut growth and yield.  相似文献