Influence of sowing windows and genotypes on growth,radiation interception,conversion efficiency and yield of guar

Crop growth largely depends on radiation. Radiation is the main impetus for photosynthesis and movement of photosynthates from source to sink. Therefore, identification of the optimum sowing windows and suitable cultivars for efficient utilization of radiation is of prime importance. A field study was conducted in red clay soil during 2014 and 2015 Kharif season and the treatments consisted of three genotypes and three sowing windows by using randomized complete block design with three replications. The effect of genotypes and sowing windows was found significant with respect to number of trifoliate leaves, leaf area ratio, dry matter production, grain numbers, pod length, test weight, grain yield, and stover yield of guar during 2014 as compared to 2015 sown crop. Statistically significant plant height, number of trifoliate leaves, number of branches, leaf area ratio, absolute growth rate, leaf area index, dry matter, grain number, pod length, grain yield, stover yield and a higher cumulative radiation interception were recorded with 15th August sown crop as compared to other sowing windows. The plant height, number of trifoliate leaves, number of branches, leaf area ratio, absolute growth rate, leaf area index, dry matter, grain number, pod length, grain yield, stover yield and maximum cumulative interception of radiation were significant with RGC-1003 as compared to RGC-936 and HG-365. It is observed that the incident PAR to dry matter accumulation conversion efficiency was varied with cultivars and different sowing windows which ranges from 0.74 g MJ⁻¹ to 0.79 g MJ⁻¹.     

Gas exchange and leaf metabolism of irrigated maize at different growth stages

Abstract

Net ecosystem exchange (NEE), leaf gas exchange and biochemical traits were investigated in an irrigated maize crop grown under Mediterranean conditions. Sub-optimal irrigation water supply determined a drought stress during the early vegetative growth stage (45–49 days after swing) that decreased NEE. Drought, in the late vegetative stage, also caused a reduction of leaf gas exchange. In the latter period, proline, glycine and serine, as well as sucrose leaf contents increased, while starch, proteins and glucose contents decreased. In the early reproductive stage, the crop experienced a longer dry spell that induced a reduction in canopy as well as in leaf gas exchanges, while protein and free amino acid contents decreased with respect to the late vegetative stage. Both ecophysiological and biochemical data demonstrate a good capacity of cultivar Pioneer PR32D99 to endure the environmental stress, related to Mediterranean summer drought, leading to an elevated dry matter yield at harvest. Photosynthetic apparatus appeared fairly resistant to soil water shortage due likely to the increased leaf content of organic solutes, such as amino acids and soluble sugars.     

Long‐term changes in forest carbon under temperature and nitrogen amendments in a temperate northern hardwood forest

Currently, forests in the northeastern United States are net sinks of atmospheric carbon. Under future climate change scenarios, the combined effects of climate change and nitrogen deposition on soil decomposition, aboveground processes, and the forest carbon balance remain unclear. We applied carbon stock, flux, and isotope data from field studies at the Harvard forest, Massachusetts, to the ForCent model, which integrates above‐ and belowground processes. The model was able to represent decadal‐scale measurements in soil C stocks, mean residence times, fluxes, and responses to a warming and N addition experiment. The calibrated model then simulated the longer term impacts of warming and N deposition on the distribution of forest carbon stocks. For simulation to 2030, soil warming resulted in a loss of soil organic matter (SOM), decreased allocation to belowground biomass, and gain of aboveground carbon, primarily in large wood, with an overall small gain in total system carbon. Simulated nitrogen addition resulted in a small increase in belowground carbon pools, but a large increase in aboveground large wood pools, resulting in a substantial increase in total system carbon. Combined warming and nitrogen addition simulations showed a net gain in total system carbon, predominately in the aboveground carbon pools, but offset somewhat by losses in SOM. Hence, the impact of continuation of anthropogenic N deposition on the hardwood forests of the northeastern United States may exceed the impact of warming in terms of total ecosystem carbon stocks. However, it should be cautioned that these simulations do not include some climate‐related processes, different responses from changing tree species composition. Despite uncertainties, this effort is among the first to use decadal‐scale observations of soil carbon dynamics and results of multifactor manipulations to calibrate a model that can project integrated aboveground and belowground responses to nitrogen and climate changes for subsequent decades.     

Development and set-up of a portable device to monitor airway exhalation and deposition of particulate matter

The aim of this study was to assess and monitor airway exhalation and deposition of particulate matter (PM). After standardizing inspiratory/expiratory flow and volumes, a novel device was tested on a group of 20 volunteers and in a field study on workers exposed to cristobalite. Both male and female subjects showed a higher percentage of deposition in the 0.5?μm channel than in the 0.3?μm channel on a laser particle counter, but it was higher in the males because of their higher exhaled lung volumes. The device was tested on a wider range of particles (0.3–0.5–1.0–2.5?μm) in the cristobalite productive division. The device has low intrasubject variability and good reproducibility, with geometric mean of %CV?相似文献   

Soil‐specific response functions of organic matter mineralization to the availability of labile carbon

Soil organic matter (SOM) mineralization processes are central to the functioning of soils in relation to feedbacks with atmospheric CO₂ concentration, to sustainable nutrient supply, to structural stability and in supporting biodiversity. Recognition that labile C‐inputs to soil (e.g. plant‐derived) can significantly affect mineralization of SOM (‘priming effects’) complicates prediction of environmental and land‐use change effects on SOM dynamics and soil C‐balance. The aim of this study is to construct response functions for SOM priming to labile C (glucose) addition rates, for four contrasting soils. Six rates of glucose (3 atm% ¹³C) addition (in the range 0–1 mg glucose g^?1 soil day^?1) were applied for 8 days. Soil CO₂ efflux was partitioned into SOM‐ and glucose‐derived components by isotopic mass balance, allowing quantification of SOM priming over time for each soil type. Priming effects resulting from pool substitution effects in the microbial biomass (‘apparent priming’) were accounted for by determining treatment effects on microbial biomass size and isotopic composition. In general, SOM priming increased with glucose addition rate, approaching maximum rates specific for each soil (up to 200%). Where glucose additions saturated microbial utilization capacity (>0.5 mg glucose g^?1 soil), priming was a soil‐specific function of glucose mineralization rate. At low to intermediate glucose addition rates, the magnitude (and direction) of priming effects was more variable. These results are consistent with the view that SOM priming is supported by the availability of labile C, that priming is not a ubiquitous function of all components of microbial communities and that soils differ in the extent to which labile C stimulates priming. That priming effects can be represented as response functions to labile C addition rates may be a means of their explicit representation in soil C‐models. However, these response functions are soil‐specific and may be affected by several interacting factors at lower addition rates.     

Modern maize hybrids in Northeast China exhibit increased yield potential and resource use efficiency despite adverse climate change

The impact of global changes on food security is of serious concern. Breeding novel crop cultivars adaptable to climate change is one potential solution, but this approach requires an understanding of complex adaptive traits for climate‐change conditions. In this study, plant growth, nitrogen (N) uptake, and yield in relation to climatic resource use efficiency of nine representative maize cultivars released between 1973 and 2000 in China were investigated in a 2‐year field experiment under three N applications. The Hybrid‐Maize model was used to simulate maize yield potential in the period from 1973 to 2011. During the past four decades, the total thermal time (growing degree days) increased whereas the total precipitation and sunshine hours decreased. This climate change led to a reduction of maize potential yield by an average of 12.9% across different hybrids. However, the potential yield of individual hybrids increased by 118.5 kg ha^?1 yr^?1 with increasing year of release. From 1973 to 2000, the use efficiency of sunshine hours, thermal time, and precipitation resources increased by 37%, 40%, and 41%, respectively. The late developed hybrids showed less reduction in yield potential in current climate conditions than old cultivars, indicating some adaptation to new conditions. Since the mid‐1990s, however, the yield impact of climate change exhibited little change, and even a slight worsening for new cultivars. Modern breeding increased ear fertility and grain‐filling rate, and delayed leaf senescence without modification in net photosynthetic rate. The trade‐off associated with delayed leaf senescence was decreased grain N concentration rather than increased plant N uptake, therefore N agronomic efficiency increased simultaneously. It is concluded that modern maize hybrids tolerate the climatic changes mainly by constitutively optimizing plant productivity. Maize breeding programs in the future should pay more attention to cope with the limiting climate factors specifically.     

Composting of municipal solid waste

This paper reviews the literature on the composting process, which is one of the technological options for the processing of municipal solid wastes (MSWs). The process assumes a great significance, particularly from the point of its economic viability, capability for recycling of nutrients and waste minimization with minimum environmental problems. A number of studies on various aspects of the composting process, including process control and monitoring parameters such as temperature, pH, moisture content, aeration, and porosity are reviewed. Salient observations on microbial properties of composting are described and details of vermicomposting, as well as a detailed analysis of patents on composting of MSW, are presented.     

Response of Cat Ventrolateral Spinal Axons to an Itch-Producing Stimulus (Cowhage)

A comparison was made between different categories of mechanically sensitive, ventrolateral spinal axons to assess their sensitivity to the itch-producing substance cowhage. Of 52 wide-dynamic-range (WDR) units, 17 had contralateral, 22 had ipsilateral, and 13 had bilateral receptive fields. Of the 5 low-threshold units, 1 had an ipsilateral receptive field and the remainder were bilateral. Among the high-threshold units, 10 were contralateral, 6 ipsilateral, and 5 bilateral. Although there was no evidence of cowhage sensitivity in either low- or high-threshold spinal axons, neurons with WDR properties were reactive to cowhage. WDR neurons were subclassified on the basis of their resting discharge pattern as having intermittent, continuous, or no resting discharge. WDR units with an intermittent pattern of resting discharge demonstrated a significant sensitivity to active cowhage and hence might be regarded as pruritogen-responsive spinal axons. Inactive cowhage was used as a control stimulus. In some WDR units with large receptive fields, there were observations suggesting convergence of chemoreceptive and mechanoreceptive inputs, which produced inhibitory as well as excitatory effects.     

Isolation of Coal Degrading Fungus from Drilled Core Coal Sample and Effect of Prior Fungal Pretreatment on Chemical Attributes of Extracted Humic Acid

Fungal degradation of low rank coal has appeared as an alternative technique for exploitation of non-fuel options. A fungal isolate, MW1, was isolated and coal sample was subjected to fungal pretreatment. The residual coal was processed for extraction of humic acid for determining the effect of such pretreatment. Extracted humic acid was analyzed on the basis of elemental composition and spectroscopy. Fungal pretreatment caused improvement in oxygen content, E₄/E₆ ratio, and absorption bands related to humic materials. Conclusively, pretreatment resulted in improving chemical attributes of humic acid molecule, thus, warranting supplementary high-tech investigations for the optimization of process upscale.