The effect of salinity on corn yield using the CERES-maize model     

José Beltrão  Jiftah Ben Asher 《Irrigation and Drainage Systems》1997,11(1):15-28

In most cases, when calculating soil water availability, only thewater content is considered. The effect of salinity on the wiltingpoint is neglected. The objective of this work is to use asimulation model (CERES-maize) in order to predict cornyields as a function of water salinity under severalenvironmental, agrotechnical, and plant characteristics. A modelis presented in which the wilting point is a function of the soilsalt content. At high salinity, the water content at wilting pointis higher than at low salinity, resulting in an insufficient amountof available water and, therefore, a reduced yield. The modelwas used to simulate several theoretical and experimentalsituations for forage corn and grain corn. Simulation resultsshowed that nitrogen fertilization increases the salinity thresholdvalue and the yield sensitivity (rate of yield reduction per unitof salinity). The also showed that forage corn is more sensitiveto salinity than grain corn. If the soil is not leached, a heaviersoil texture has a higher salinity threshold value. On the otherhand, if the soil is leached, the soil texture has no influence onthe salinity threshold value and the yield is less sensitive tosalinity in sandy soils. The determination coefficient (r²= 0.75) indicated that the results of the simulations were in goodagreement with the field data.  相似文献   

Can carbon sequestration markets benefit low-income producers in semi-arid Africa? Potentials and challenges   总被引：1，自引：0，他引：1  

Carlos Perez  Carla Roncoli  Constance Neely  Jean L. Steiner 《Agricultural Systems》2007

The Clean Development Mechanism (CDM) of the Kyoto Protocol of the United Nations Framework Convention on Climate Change allows a country that emits C above agreed-upon limits to purchase C offsets from an entity that uses biological means to absorb or reduce greenhouse emissions. The CDM is currently offered for afforestation and reforestation projects, but may apply subsequently to sequestration in agricultural soils. Additionally, markets outside of the Protocol are developing for soil C sequestration.  相似文献   

Multivariate analysis of invasive plant species distributions in southern US forests     

Lázaro-Lobo  Adrián  Ramirez-Reyes  Carlos  Lucardi  Rima D.  Ervin  Gary N. 《Landscape Ecology》2021,36(12):3539-3555

Landscape Ecology - Invasive plants cause significant impacts in forested areas throughout the world. However, little is known about the relative importance of environmental drivers on the...  相似文献   

Habitat quality,not habitat amount,drives mammalian habitat use in the Brazilian Pantanal     

Regolin  André Luis  Oliveira-Santos  Luiz Gustavo  Ribeiro  Milton Cezar  Bailey  Larissa Lynn 《Landscape Ecology》2021,36(9):2519-2533

Landscape Ecology - An understanding of species-habitat relationships is required to assess the impacts of habitat fragmentation and degradation. To date, habitat modeling in fragmented landscapes...  相似文献   

Sediment production from unpaved roads in a sub-tropical dry setting — Southwestern Puerto Rico   总被引：1，自引：0，他引：1  

Carlos E. Ramos Scharrón 《CATENA》2010

The threat imposed by increased sediment loading rates ranks among the most important stressors affecting coral reef ecosystems worldwide. This study represents an effort to quantify the effects of unpaved roads on erosion rates in a dry sub-tropical area of Puerto Rico and is intended to aid in developing scientifically-based erosion mitigation strategies. Hence, the specific objectives of this study were to: (1) measure sediment production rates from unpaved roads; (2) evaluate the effect of precipitation, rainfall erosivity, slope, plot length, and vegetation cover on sediment production rates; and (3) compare measured sediment production rates to published surface erosion data from roaded and natural sites in the Eastern Caribbean. Sediment production from nine abandoned road segments with varying slopes and plot lengths were measured with sediment traps in southwestern Puerto Rico from August 2003 to September 2005.  相似文献   

LED-Induced Chlorophyll Fluorescence Spectral Analysis for the Early Detection and Monitoring of Cadmium Toxicity in Maize Plants     

Airon José da Silva  Clístenes Williams Araújo do Nascimento  Artur da Silva Gouveia-Neto  Elias Arcanjo da Silva-Jr 《Water, air, and soil pollution》2012,223(6):3527-3533

Chlorophyll fluorescence spectral analysis permits detection, monitoring, and evaluation of abiotic stresses upon healthy plants using illumination of a light source in the UV?CVIS spectral range. This technique indirectly assesses the amount of physiological stress caused by photosynthetic damage, specifically damage to photosystem II, in plants. The objective of this study was to detect the toxicity of cadmium in maize plants via spectral analysis of chlorophyll fluorescence. The analysis is noninvasive and nondestructive and is used to follow the temporal evolution of changes in the chlorophyll content and physiological state of Zea mays L. seedlings under cadmium stress. Conventional techniques were also used to evaluate the dry matter production and Cd accumulation in plant leaves. Plants exhibited a notable reduction in dry matter production and chlorophyll levels with the administration of increasing doses of Cd in the nutrient solution. The fluorescence analysis was sensitive to changes caused by Cd in maize plants, detecting damage caused by different treatments before visual symptoms were observed. This technique has a practical application and produces rapid results that can be used in the evaluation of Cd-induced stress in plants and the detection of areas contaminated by this element.  相似文献   

Dynamic oxygen mapping in the root zone by fluorescence dye imaging combined with neutron radiography   总被引：1，自引：0，他引：1  

Nicole Rudolph  Hanna G. Esser  Andrea Carminati  Ahmad B. Moradi  André Hilger  Nikolay Kardjilov  Stefan Nagl  Sascha E. Oswald 《Journal of Soils and Sediments》2012,12(1):63-74

Purpose  

The rooted zone of a soil, more precisely the rhizosphere, is a very dynamic system. Some of the key processes are water uptake and root respiration. We have developed a novel method for measuring the real-time distribution of water and oxygen concentration in the rhizosphere as a biogeochemical interface in soil. This enables understanding where and when roots are active in respect to root respiration and water uptake and how the soil responds to it.  相似文献   

基于SIRMOD模型的畦灌入渗参数估算及灌溉模拟   总被引：3，自引：2，他引：3  

郑和祥  史海滨  朱敏  刘宏云  José Manuel Gon?alves 《农业工程学报》2009,25(11):29-34

土壤入渗参数是地面灌溉中制定灌溉制度、评价灌水质量的重要指标。针对现有估算方法存在计算工作量较大、精度不高的现状,根据田间实测资料,利用SIRMOD模型,对小麦畦灌条件下田间土壤入渗参数进行了估算。与用Maheshwari法计算结果较为接近,差异均在2.0%以内。根据估算的土壤入渗参数,应用SIRMOD模型进行了多组合灌溉模拟,在保证灌水质量较高的条件下,得出了在不同亏缺水量时的适宜灌水量和灌水流量,通过田间实例验证表明模拟效果较好。  相似文献   

Stir bar sorptive extraction combined with GC-MS analysis and chemometric methods for the classification of South African Wines according to the volatile composition   总被引：1，自引：0，他引：1  

Tredoux A  de Villiers A  Májek P  Lynen F  Crouch A  Sandra P 《Journal of agricultural and food chemistry》2008,56(12):4286-4296

A simple method for the analysis of major wine volatiles and semivolatiles by stir bar sorptive extraction in combination with thermal desorption and gas chromatography-mass spectrometry (SBSE-TD-GC-MS) was developed. Significant experimental parameters such as extraction time, temperature, salt addition, pH, and thermal desorption parameters were optimized to provide a sensitive and robust analytical method. The method provided good repeatability (%RSD < 10%) for 38 major wine volatile compounds, including alcohols, acids, esters, phenols, aldehydes, ketones, and lactones. Quantitative data for 62 South African red and white wines were used to study the suitability of major volatile data for the differentiation of wine samples according to grape variety or cultivar. Principal component analysis (PCA) and cluster analysis (CA) showed that most of the variation in volatile composition between wine samples could be ascribed to differences in wine age, wood contact, and fermentation practices. Despite the contribution of these factors, discriminant analysis (DA) was successfully applied to the classification of red and white wine samples according to cultivar.  相似文献   

Orosensory-directed identification of astringent mouthfeel and bitter-tasting compounds in red wine     

Hufnagel JC  Hofmann T 《Journal of agricultural and food chemistry》2008,56(4):1376-1386

Application of sequential solvent extraction, followed by HPLC combined with the taste dilution analysis, enabled the localization of the most intense velvety astringent, drying, and puckering astringent, as well as bitter-tasting, compounds in red wine, respectively. Isolation of the taste components involving gel adsorption chromatography, ultrafiltration, and synthesis revealed the identification of 26 sensory-active nonvolatiles, among which several hydroxybenzoic acids, hydroxycinnamic acids, flavon-3-ol glycosides, and dihydroflavon-3-ol rhamnosides as well as a structurally undefined polymeric fraction (>5 kDa) were identified as the key astringent components. In contradiction to literature suggestions, flavan-3-ols were found to be not of major importance for astringency and bitter taste, respectively. Surprisingly, a series of hydroxybenzoic acid ethyl esters and hydroxycinnamic acid ethyl esters were identified as bitter compounds in wine. Taste qualities and taste threshold concentrations of the individual wine components were determined by means of a three-alternative forced-choice test and the half-mouth test, respectively.  相似文献