Growth and nitrogen yield of Leucaena/maize mixed culture as affected by salt stress and gypsum

Leucaena leucocephala is a leguminous, deep rooting tree, increasingly utilized in “Low Input” mixed cultures under arid conditions to reduce mineral N requirements and to improve nutrient cycling. This work was carried out to evaluate the growth and N yield of Leucaena and Maize in sand culture with low (0,6 mM) nitrogen supply under saline conditions (NaCl; NaCl + CaCl₂; NaCl + CaSO₄). While the low N nutrient solution failed to sustain maize growth in monoculture, both Leucaena and maize grew well in mixed culture with considerable N yields suggesting significant transfer of N from Leucaena to maize. NaCl depressed the uptake of Ca and S and reduced growth and N yields of both crop species. CaSO₄ counteracted partly the NaCl-effects.     

Comparison of nutritional and antinutritional factors in soybean and fababean seeds with or without cortex

The composition and contents of nutritional factors such as proteins, lipids, carbohydrates, fibers, amino acids, and antinutritional factors such as trypsin inhibitors, phytic acid, and tannins were compared in soybean and fababean seeds with emphasis placed on the nutritional improvement of the seeds by cortex removal. Protein hydrolysis analysis for both whole seeds and seed with cortex removed revealed the presence of a large amount of lysine, arginine, aspartic acid, glutamic acid, glycine, and leucine while these seeds contained a low level of tryptophan, cystine, and methionine. Some antinutritional factors such as trypsin inhibitors, phytic acid, and tannins were detected in soybean and fababean seeds: phytic acid content and trypsin inhibitor activity were higher in soybean seeds than in fababean seeds while the difference in the tannin content was less pronounced. It was found that most of the tannins occurred in the cortex of the soybean and fababean seeds. Tannins are polyphenolic compounds that readily form indigestible complexes with proteins and other macromolecules under specific environmental conditions. By removal of the cortex, tannins were almost completely eliminated without changes in the protein composition and amino acids. From these results, it is assumed that since soybean and fababean seeds contained a high concentration of antinutritional factors in the cortex such as tannins, the utilization of the legume seeds after removal of all of the cortex is suitable for human diet or industrial products.     

Investigation of irrigation performance at the tertiary canal level in the Nile Delta of Egypt

Paddy and Water Environment - One of the objectives of the Irrigation Improvement Project (IIP) in the Nile Delta, Egypt, is to facilitate equitable water distribution and improve on-farm...     

Safe and high quality food production using low quality waters and improved irrigation systems and management: SAFIR

The present paper presents the SAFIR project (www.safir4eu.org), which addresses two fundamental problems that over the past decade increasingly have become concerns of the general public: the one problem being the jeopardizing of safety and quality of our food products, while the other being the increasing competition for clean freshwater. The SAFIR project has a multi-disciplinary approach, which integrates the European as well as the global dimension of the EU-policy on food quality and safety. The main driving force behind the project idea is new research results that demonstrated that scheduled uneven irrigation patterns can increase the water use efficiency as well as the quality of vegetable crops. Furthermore, recent innovations in the water treatment and irrigation industry have shown potential for the use of low quality water resources, such as reclaimed water or surface water in peri-urban agriculture, for irrigation of vegetable crops without threaten food safety and quality. The results of SAFIR were achieved from field experiments in Europe and China and modeling activities both at field and farm scale. The present article describes the structure of the project and highlights the main findings and recommendations of the project described in detail in already published papers and in accompanying papers in this special issue.     

ROLE OF SALICYLIC ACID IN REGULATION OF CADMIUM TOXICITY IN WHEAT (TRITICUM AESTIVUM L.)

The present study is focused on the possible mediatory role of salicylic acid (SA) under cadmium (Cd⁺²) toxicity. Cadmium treatments resulted in the inhibition of root dry biomass, root elongation and increased Cd accumulation in roots. Pretreatment of seeds with SA (500 μM) for 20 hrs resulted in protection against Cd, increased root dry biomass, root elongation and minimal accumulation of cadmium. Cadmium chloride (CdCl₂; 0.0, 100, 400 and 1000 μM) produced a significant inhibition in chlorophyll, photosynthetic efficiency [carbon dioxide (¹⁴CO₂)-fixation], relative water content (RWC) and abscisic acid (ABA) content. Pretreatment of seeds with SA alleviated the Cd negative effect on these parameters. A drop in the activities of carboxylating enzymes, phosphoenol pyruvate carboxylase (PEPC, EC 4.1.1.31), and ribulose1,5-bisphosphate carboxylase (RuBPC, EC 4.1.1.39) were observed in Cd treated plants. Pretreatment with SA ameliorated the inhibitory effect of Cd on the studied enzymatic activities. Cadmium applied to salicylic acid free plants increased the level of stress metabolites, malondialdehide (MDA), hydrogen peroxides, and free proline content. Salicylic acid pretreatment decreased the toxic effect level of cadmium manifested by lower lipid peroxidation, lesser production of H₂O₂ and reduction in free proline content. The ultrastructural investigation of the root cells of wheat exposed to different concentrations of Cd for 15 days was carried out. The results indicated that Cd induced several obvious ultrastructural changes such as increased vacuolation, condensed cytoplasm with increased density of the matrix, reduction of mitochondrial cristae, severe plasmolysis, highly condensed nuclear chromatin and increment of disintegrated organelles. Electron dense granules appeared between the cell wall and plasmalemma. In vacuoles, electron dense granules encircled by the membrane were aggregated and formed into larger precipitates, which increase in number and volume as a consequence of excessive Cd exposure. An important issue arising from this study was how the short-term treatment with SA affected several physiological processes, such as plant growth, photosynthesis, and antioxidant defense system. We assume that the beneficial effect of SA during an earlier growth period could be related to avoidance of cumulative damage upon exposure to cadmium. One of the important roles of SA in inducing resistance to various environmental stresses is manifested by its ability to express genes that code for pathogenesis-related proteins or defense-related enzymes. Also, SA could form a complex with Cd that may provide Cd tolerance.     

Calibration and validation of SALTMED model under dry and wet year conditions using chickpea field data from Southern Portugal

The SALTMED model is one of the few available generic models that can be used to simulate crop growth with an integrated approach that accounts for water, crop, soil, and field management. It is a physically based model using the well-known water and solute transport, evapotranspiration, and water uptake equations. In this paper, the model simulated chickpea growth under different irrigation regimes and a Mediterranean climate. Five different chickpea varieties were studied under irrigation regimes ranging from rainfed to 100 % crop water requirements, in a dry and a wet year. The calibration of the model using one of the chickpea varieties was sufficient for simulating the other varieties, not requiring a specific calibration for each individual chickpea variety. The results of calibration and validation of the SALTMED model showed that the model can simulate very accurately soil moisture content, grain yield, and total dry biomass of different chickpea varieties, in both wet and dry years. This new version of the SALTMED model (v. 3.02.09) has more features and possibilities than the previous versions, providing academics and professionals with a very good tool to manage water, soil, and crops.     

Ultrastructural studies on the pancreatic acini in duck (Anas boscas) and pigeon (Columba livia)

The aim of this research work was to study the histological structure of the pancreatic acini by transmission electron microscope in two avian species, duck and pigeon. The specimens were collected and processed for electron microscopic study. The results showed that the acini of the two avian species were two types; the first one was an electron dense and the second one an electron lucent. The light acinar cells were larger in size than the dark cells. These cells contained centrally located ovoid nuclei with prominent nucleoli and abundant euchromatin. The cytoplasm was electron lucent, with many rough endoplasmic reticulum, polymorphic mitochondria. Numerous zymogen granules were distributed in the basal part and around the nucleus, so these cells considered active cells. The dark acinar cells were characterized by an electron dense cytoplasm. The most prominent cell organelle in these cells were the zymogen granules that appeared in different sizes while other organelles as mitochondria, and rough endoplasmic reticulum were inconspicuous or few, so these cells were considered as inactive cells. The nucleus with indented nuclear membrane located centrally with prominent nucleoli and abundant heterochromatin. Prominent intercellular spaces between the individual acinar cells, as well as well-developed basement membrane separating the electron dense cells and the lumen contained the secretion between acinar cells. It could be concluded that the acinar cells in ducks and pigeons were divided into two types, that is, light and dark acinar cells which mainly attributed to the activity of these cells.     

Effect of irrigation methods,management and salinity of irrigation water on tomato yield,soil moisture and salinity distribution

The increasing demand for irrigation water to secure food for growing populations with limited water supply suggests re-thinking the use of non-conventional water resources. The latter includes saline drainage water, brackish groundwater and treated waste water. The effects of using saline drainage water (electrical conductivity of 4.2–4.8 dS m⁻¹) to irrigate field-grown tomato (Lycopersicon esculentum Mill cv Floradade) using drip and furrow irrigation systems were evaluated, together with the distribution of soil moisture and salt. The saline water was either diluted to different salinity levels using fresh water (blended) or used cyclically with fresh water. The results of two seasons of study (2001 and 2002) showed that increasing salinity resulted in decreased leaf area index, plant dry weight, fruit total yield and individual fruit weight. In all cases, the growth parameters and yield as well as the water use efficiency were greater for drip irrigated tomato plants than furrow-irrigated plants. However, furrow irrigation produced higher individual fruit weight. The electrical conductivity of the soil solution (extracted 48 h after irrigation) showed greater fluctuations when cyclic water management was used compared to those plots irrigated with blended water. In both drip and furrow irrigation, measurements of soil moisture one day after irrigation, showed that soil moisture was higher at the top 20 cm layer and at the location of the irrigation water source; soil moisture was at a minimum in the root zone (20–40 cm layer), but showed a gradual increase at 40–60 and 60–90 cm and was stable at 90–120 cm depth. Soil water content decreased gradually as the distance from the irrigation water source increased. In addition, a few days after irrigation, the soil moisture content decreased, but the deficit was most pronounced in the surface layer. Soil salinity at the irrigation source was lower at a depth of 15 cm (surface layer) than that at 30 and 60 cm, and was minimal in deeper layers (i.e. 90 cm). Salinity increased as the distance from the irrigation source increased particularly in the surface layer. The results indicated that the salinity followed the water front. We concluded that the careful and efficient management of irrigation with saline water can leave the groundwater salinity levels unaffected and recommended the use of drip irrigation as the fruit yield per unit of water used was on average one-third higher than when using furrow irrigation.     

Screening for Antifungal Potential of Plant Extracts of Fifteen Plant Species Against Four Pathogenic Fungi Species

The antifungal activity of fifteen wild plant species grown in the Al-Qassim region, Saudi Arabia, was investigated against the fungi species Fusarium solani, Botrytis cinerea, Alternaria alternata and Stemphylium botryosum at concentrations of 10, 20, 40 and 80?g/L. The inhibitory effect of test extracts varied among examined fungi, and Fusarium solani exhibited the least sensitivity compared to other fungi species. Antifungal activity of the tested extracts was proportional to the applied dose. Extracts of Lactuca virosa, Neurada procumbens, Ochradenus baccatus and Cyperus conglomerates showed relatively low inhibition effects on the fungi species. The most effective plants were Pulicaria undulata, Artemisia monosperma, Prosopis juliflora, Withania somnifera and Rumex vesicarius. At 80?g/L, extracts of these plant species reduced mycelial growth of Botrytis cinerea by 16.5–32.2%, of Fusarium solani by 11.1–27.9%, of Alternaria alternaae by 26.9–63.5% and of Stemphylium botryosum by 22–40%. The methanolic extract of the most effective plant species was further fractioned with hexane, methylene chloride and ethyl acetate. The obtained fractions varied in their effects on mycelial growth of the four tested fungi. Using the same fraction resulted in different inhibition effects on mycelial growth of all tested fungi. The antifungal activity of each crude extract tended to be distributed among its three fractions, probably because the bioactive components were also distributed among the fractions.