Nitrogen fertigation of greenhouse-grown cucumber

Summary This greenhouse study investigated the response of trickle-irrigated cucumber (Cucumis sativa cv. ‘Petita’) to three N levels applied with every irrigation via the irrigation stream. The plants were grown in pots filled with 12 kg of soil. Water containing 5.8, 11.8, or 17.8 mmol N/l, and uniformly supplied with 2.0 and 3.9 mmol/l of P and K, respectively, was applied two to three times daily. In all treatments of 0.3 leaching fraction was allowed. The resulting total N applications were 15.7, 31., and 47.2 g N/plant. The total amount of water applied was 1851/plant. Total N and NO₃-N, in lajinae and petioles, increased with increasing N level whereas P and K in generated decreased. Although different NO₃/NH₄ ratios in the treatments may have influeced the response to N, it could be concluded that the highest yield was obtained with 11.8 mmol N/1 due to increased number of fruit. In the root volume of this treatment the NO₃-N concentration in the soil solution was aroun 7 mmol/1 for most of the growing season. The dry matter concentration of fruits was not affected by the N levels. It was concluded that 11.8 mmol N/1 applied with every irrigation via the irrigation stream is adequate to cover the needs of greenhous-grown cucumber for higher yield (9.42 kg/plant over a harvesting period of 93 days).     

Internode length in Pisum. I. The effect of the Le/le gene difference on endogenous gibberellin-like substances

The allelopathic potential of the dry fruits of Washingtonia filifera (L. Linden) H. Wendl. was investigated. Leachates from fruits inhibited the germination of lettuce, wheat, red cabbage and cucumber seeds. The inhibitory effect was partly neutralized by kinetin (20 mg 1⁻¹) and gibberellic acid (50 mg 1⁻¹). The effect of kinetin was more pronounced at 25°C than at 20°C. Substances inhibiting germination were localized in the pericarp of the fruit and were resistant to high temperature.     

Adaptation of the tetrazolium method for testing the seed viability, and scanning electron microscopy study of some Western European orchids

A modified tetrazolium method was formulated for use with seeds of Western European orchids. The sequence of treatments which gave the highest percentage of coloured (i.e. viable) embryos was: (1) pretreatment in a solution of 5% (w/v) Ca(OCl)₂+ 1% (v/v) Tween-80, (2) soaking for 1 day in sterile water, (3) the classical tetrazolium test. The optimal duration of the pretreatment in Ca(OCl)₂+ Tween-80 depends upon the species, and to investigate the effect a scanning electron microscopy study was performed on the testa of 3 species. For a given species, the optimal pretreatment period was not affected by the year of harvest or the source of the seed lots.     

Enzyme activities in a clay-loam soil amended with various crop residues

Summary Amylase, dehydrogenase, arylsulphatase and phosphatases activities were measured in a clay-loam soil amended with seven different crop residues. All enzyme activities, except phosphomonoesterase, were generally higher in the derived soil samples than in the original soil. Addition of tobacco and sunflower residues caused an increase on most of the enzyme activities while tomato residues increased only the amylase and phosphodiesterase activities. As the enzyme activities were positively correlated to each other, a common source of the enzymes is suggested even though the coefficients of correlation demonstrate that only a low percentage of the variability can be ascribed to the interactions among enzyme activities.     

Enumeration of denitrifying microbial populations in turf

Summary Denitrifer populations of a silt and silt loam soil under a Kentucky bluegrass turf were enumerated using the most probable number (MPN) procedure. The influence of soil texture, soil depth, soil moisture, and additions of nitrate fertilizer on denitrifier populations were determined. Saturated soil conditions increased denitrifier populations 87-fold in the silt soil and 121-fold in the silt loam soil. Denitrifier populations did not differ significantly between soil depths and additions of fertilizer nitrate did not influence populations.     

Demography and blood donation trends in Saudi Arabia: A nationwide retrospective,cross-sectional study

BackgroundBlood product supply and utilization are understudied in Saudi Arabia. This study evaluates the trends in Saudi blood banks readiness, donors’ demography, and blood product utilization and wastage.Study design and methodsA retrospective, cross-sectional study of records obtained from the Ministry of Health (MOH) was initiated to report trends and statistics on annual whole blood donors and blood product utility from 2010 to 2020. Data collected in 2020 was further characterized for donors’ demographics, laboratory readiness, and staffing.ResultsThe average number of annual blood donors over the last decade (2010–2020) was 325,847.3 ± 43,160. The forecasted blood donation and dispatch trends suggest a significant increase in blood demand (R² = 0.7582) over annual donation rates (R² = 0.2356). In 2020, 342,460 nationwide blood donations were registered in governmental donation centers and females constituted a mere 2.5 %. Approximately 60 % of whole blood donation was voluntary, 36% was compensatory, and 4% was part of driving license renewal. The highest blood donation rate per 1,000 inhabitants was observed in Taif (69.8) and Alqonfoda (45.0). Eastern directory and Madinah had the most successful donation campaigns attracting 53% and 50% of total annual donations, respectively. Notably, Tabouk, Hai’l, and Albaha had the highest blood product wastage medians.ConclusionBlood donation rates and impetus, staffing ratios, and laboratory readiness and wastage varied among the various directories. Laboratory managers and medical directors need to increase efforts to refine current guidelines in order to comply with the transformation plan of the health sector.     

The Pressurized Porous Surface Model: An improved tool to study bacterial behavior under a wide range of environmentally relevant matric potentials

To study bacterial behavior under varying hydration conditions similar to surface soil, we have developed a system called the Pressurized Porous Surface Model (PPSM). Thin liquid films created by imposing a matric potential of − 0.4 MPa impact gene expression and colony development in Pseudomonas putida.     

Preparation of capacitor’s electrode from sunflower seed shell

Series of nanoporous carbons are prepared from sunflower seed shell (SSS) by two different strategies and used as electrode material for electrochemical double-layer capacitor (EDLC). The surface area and pore-structure of the nanoporous carbons are characterized intensively using N₂ adsorption technique. The results show that the pore-structure of the carbons is closely related to activation temperature and dosage of KOH. Electrochemical measurements show that the carbons made by impregnation-activation process have better capacitive behavior and higher capacitance retention ratio at high drain current than the carbons made by carbonization-activation process, which is due to that there are abundant macroscopic pores and less interior micropore surface in the texture of the former. More importantly, the capacitive performances of these carbons are much better than ordered mesoporous carbons and commercial wood-based active carbon, thus highlighting the success of preparing high performance electrode material for EDLC from SSS.