Ground-level hyperspectral imagery for detecting weeds in wheat fields

Site-specific weed management can allow more efficient weed control from both an environmental and an economic perspective. Spectral differences between plant species may lead to the ability to separate wheat from weeds. The study used ground-level image spectroscopy data, with high spectral and spatial resolutions, for detecting annual grasses and broadleaf weeds in wheat fields. The image pixels were used to cross-validate partial least squares discriminant analysis classification models. The best model was chosen by comparing the cross-validation confusion matrices in terms of their variances and Cohen’s Kappa values. This best model used four classes: broadleaf, grass weeds, soil and wheat and resulted in Kappa of 0.79 and total accuracy of 85 %. Each of the classes contains both sunlit and shaded data. The variable importance in projection method was applied in order to locate the most important spectral regions for each of the classes. It was found that the red-edge is the most important region for the vegetation classes. Ground truth pixels were randomly selected and their confusion matrix resulted in a Kappa of 0.63 and total accuracy of 72 %. The results obtained were reasonable although the model used wheat and weeds from different growth stages, acquisition dates and fields. It was concluded that high spectral and spatial resolutions can provide separation between wheat and weeds based on their spectral data. The results show feasibility for up-scaling the spectral methods to air or spaceborne sensors as well as developing ground-level application.     

Evaluation of garlic cultivars for salinity tolerance

Salinity tolerance in garlic cultivars was studied in pots. A 50% yield reduction occurs at 5.60-7.80 dS m1, depending on genotype. It was estimated that if soil salinity exceeds 1.70 dS m_l, the mean garlic yield declined by 1.68% per unit increase in soil salinity.     

Simulation of peak-demand hydrographs in pressurized irrigation delivery systems using a deterministic–stochastic combined model. Part II: model applications

A deterministic–stochastic combined model named HydroGEN was developed, as described in a companion paper (Part I: Model development), to enable the simulation of demanded daily volumes and hourly flow rates during peak periods in pressurized irrigation delivery networks. The model was applied to a pilot large-scale irrigation system located in southern Italy for calibration and for testing its reliability in analyzing the operation of large-scale pressurized delivery systems through the simulated flow configurations. Daily input data on rainfall, temperature, solar radiation, wind speed and relative humidity were gathered from a meteorological station located within the study area, whereas information on local irrigation management practices were collected through interviews with farmers and from extension specialists. The model was tested at different management levels, from district to sector and hydrants. The model testing was supported by the use of high-resolution remote-sensing imagery acquired on a single overpass date in 2006 and then classified and recoded following a ground-truthing campaign conducted during the same year. Simulations were performed to identify the 10-day peak-demand period and to generate the hydrographs of daily volumes and of hourly flow rates. Results from the different simulations were compared with historical datasets of irrigation volumes and discharges recorded during the 2008 and 2009 seasons at the upstream end of the irrigation network under study, at a sector level during the 2007 season and at selected delivery hydrants during the 2005 season. Some discrepancies between simulated and recorded data were noted that can be related to small errors in estimating crop and soil parameters, application efficiency at field level, as well as to large variability in irrigation management practices followed by local farmers. Overall, the results from testing showed that the model is capable of forecasting with good accuracy the timing of peak-demand periods, the irrigation volumes demanded during the season, as well as the hydrographs of daily volumes and hourly flow rates withdrawn by farmers during these peak-demand periods, especially when it is applied to large multi-cropped command areas.     

Effect of soybean (Glycine max L.) on the hormonal milieu of male rats

Effect of soybean (Glycine max) on serum level of some sex hormones: testosterone, follicle stimulating hormone (FSH), luteinizing hormone/interstitial cell stimulating hormone (LH/ICSH), estradiol and prolactin in male rats was investigated. Twenty male albino rats of 12 weeks old with similar body weights were assigned to four groups of 5 rats each and treatment with soybean meal at 100, 200 and 300 mg kg(-1) body weight, respectively daily for 8 weeks. Blood samples collected through cardiac puncture were assayed for levels of hormones. There were dose-dependent effects of the soybean meal on the serum concentration of the hormones. The treatment significantly reduced the levels of testosterone and FSH in the serum while it significantly increased the levels of estradiol, LH/ICSH and prolactin. The results show that soybean (Glycine max) had strong capability to disrupt hormonal functions. Hence, its indiscriminate use could increase the risk of infertility in males.     

Relationship between total sulphur and sulphur amino acids in chickpea (Cicer arietinum L.) and pigeonpea (Cajanus cajan [L.] Millsp.)

Total sulphur was determined in seed meal of 30 chickpea and 24 pigeonpea cultivars by the wet digestion procedure and by using the Leco sulphur analyser. Methionine and cystine were determined after performic acid oxidation in an amino acid analyser. The two methods used for total sulphur determinations were highly correlated (r=0.943). Percent meal protein was significantly correlated (r=0.476) with total sulphur in chickpea but not in the case of pigeonpea. Total sulphur content exhibited a significant positive correlation (r=0.651) with sulphur amino acids of pigeonpea when expressed as percent of protein but not in the case of chickpea. Correlation coefficients between total sulphur and sulphur amino acids when the results were expressed as percent of sample were positive for both chickpea (r=0.494) and pigeonpea (r=0.534). The amount of sulphur in methionine and cystine accounted for 54.8% of the total sulphur in chickpea and for 75.5% in pigeonpea. In both chickpea and pigeonpea, methionine was positively and significantly correlated with cystine when they were expressed either as percent of sample or as percent of protein.Submitted as J.A. no. 159 by the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT).     

Interactions of fungicide-herbicide combinations against plant pathogens and weeds

The fungicide cyproconazole and four herbicides, DNOC, dicamba, ioxynil and bromoxynil, were tested singly and in mixtures against Rhizoctonia cerealis (in vitro and on wheat) and against Pseudocercosporella herpotrichoides (in vitro, as well as against two weeds, Avena fatua and Sinapis alba. Cyproconazole showed very strong fungicidal acitivity against both fungi. DNOC was inhibitory to the fungi in vitro but had little effect on the disease; dicamba had low activity against the fungi in vitro but prevented the disease on wheat. Ioxynol and bromoxynil were moderately fungitoxic both in vitro and against the disease. Cyproconazole-herbicide mixtures were synergistic in their action against both fungi in vitro and against the disease. The level of synergism depended on the relative proportion of fungicide and herbicide components in the mixtures. Mixtures of herbicides with cyproconazole against weeds were at best additive in their activity.     

Comparison of haemodynamic changes during two surgical methods for neutering female dogs

The aim was to investigate if intraoperative registrations of blood pressure and heart rate could be used to estimate surgical trauma. In a prospective clinical trial, registrations in eight dogs neutered by laparoscopic ovariectomy (LOE) were compared with eight dogs subjected to open ovariohysterectomy (OHE). For comparisons phases were used: phase zero = steady state after induction of anaesthesia; phase one = opening of abdomen; phase two = severing of ovarian pedicles; and, phase three = abdominal closure. During LOE, mean systolic blood pressure increased by 7 mm Hg (p = 0.05) and 15 mm Hg (p = 0.01) from phase zero to phase one and two, respectively, and during OHE by 3 mm Hg (ns) and 29 mm Hg (p < 0.0001), respectively. The increase from phase one to phase two differed between groups (p = 0.03). Heart rate did not change. Frequent intraoperative measurements of blood pressure appear a promising method for evaluating surgical trauma.