Cuticular cracking in pepper fruit. I. Effects of night temperature and humidity

Summary

The objective of the present study was to characterize some of the anatomical and physiological characteristics of fruit cracking in bell pepper (Capsicum annuum L.). Scanning-electron micrographs show that initiation of fruit cracking in bell pepper is by formation of mini-cracks on the cuticle layer; these then enlarge into cracks and traverse the epidermal cells. Pepper cultivars differ in their sensitivity to cracking, partly because of differences in fruit pericarp thickness. Limitation of night transpiration by high humidity or low temperature increased the turgor potential of the fruit pericarp and enhanced cracking. Likewise, leaf pruning suppressed night transpiration and concomitantly increased cracking. Fruit cuticle transpiration was found to be low in the early stages of fruit development and to increase as the fruit became susceptible to cracking. Environmental conditions which enhanced cracking also increased cuticle transpiration in a sensitive pepper cultivar but not in a less sensitive one. We suggest that fruit cracking in bell pepper occurs because reduction in night transpiration causes high turgor pressure in the fruit. As the cuticle becomes permeable to water, the inner turgor pressure causes the cuticle to crack. Differences in cultivar sensitivity may be partly due to differences in pericarp thickness and cuticle properties, but additional factors may be involved.     

Sperm quality and selected biochemical markers of seminal plasma at the beginning of the reproductive period of common carp, Cyprinus carpio L.

Changes in semen quality and selected biochemical markers were analyzed during a week of spawning season of common carp Cyprinus carpio L. Semen was obtained twice, on May 30 and on June 7, and each time it was collected 24 h after hormonal stimulation using Ovopel [(d-Ala⁶, Pro⁹ NEt)-mGnRH + metoclopramide] in 1 pellet kg^?1. The total volume of semen (ml), volume of semen per kg of body weight (ml kg^?1 b.w.), sperm concentration (×10⁹ ml^?1), total number of sperm per kg of body weight (×10⁹ kg^?1 b.w.), pH of semen, pH of seminal plasma, seminal plasma osmotic pressure (mOsm kg^?1) and the total protein content in seminal plasma (mg ml^?1) were determined. A 10 mM Tris buffer containing 100 mM NaCl with 0.5 % BSA (pH 9.0, osmolality 200 mOsm kg^?1) was used to activate sperm. The following computer-assisted sperm analysis (CASA) parameters were determined: percentage of motile sperm (MOT, %), progressively motile sperm (PRG, %), curvilinear velocity (VCL, μm s^?1), straight-line velocity (VSL, μm s^?1), movement linearity (LIN, %), wobbling index (WOB, %), amplitude of lateral head displacement (ALH, μm) and beat cross-frequency (BCF, Hz). The volume of semen per kg of BW, total number of sperm per kg of BW and semen pH were significantly lower at the second semen sampling compared to the first semen sampling. Volume of semen at the second sampling correlated positively with CASA parameters. A lack of differences among CASA parameters between both collection periods indicates good quality of carp sperm hormonally stimulated with Ovopel twice at a 1-week interval.     

Nematicidal activity of Ochradenus baccatus against the root‐knot nematode Meloidogyne javanica

Ochradenus baccatus is a widely distributed shrub in desert regions of the Middle East and North Africa. This plant's nematicidal activity against the root‐knot nematode Meloidogyne javanica was evaluated because it has been found to contain exceptionally high levels of glucosinolates. In in vitro assays with aqueous extracts of the plant, 100% of second‐stage juveniles were immobilized after exposure to 4% root‐core extract for 48 h; 8% root‐core extract suppressed their hatching by 87%, whereas stem, flower and root bark showed lower activity. Incorporation of root core or bark into the soil, as fresh or dry powder at 1 and 0·5% (w/w), respectively, reduced the number of nematodes recovered from the soil by 95–100%, whereas the flower and stem were much less effective. Results from further pot experiments indicated that only the root bark consistently contains nematicidal compounds which are effective in soil, whereas the nematicidal activity of the root core in soil was inconsistent. The presence of non‐volatile lipophilic and lipophobic nematicidal compounds in the root bark was suggested by extraction with different polar solvents, but these compounds do not seem to be isothiocyanates – glucosinolate‐hydrolysed compounds with nematicidal activity. Very poor host status of Ochradenus baccatus to M. javanica, M. incognita and M. hapla, but with root‐penetration rates of juveniles similar to those in tomato roots, suggest that this plant may be used as a cover plant or trap plant to reduce nematode populations in the soil.     

Lipid biomarkers and their environmental significance in mine soils from Eastern Europe

The present study describes signature lipid biomarkers in reclaimed mine soils (RMSs), an unreclaimed spoil and a natural soil (Vertisol) for a major coal mine basin in Eastern Europe. Alkanes, fatty acids and fatty alcohols, as well as coal biomarkers were abundant in the mine soils and the unreclaimed spoil. The alkanes distribution in the RMSs was bimodal with maxima at C₁₈ and C₂₉/C₃₁ and points at two origins for the alkanes, terrigenous plants, including soil borne and from the coal source. Fatty acid carbon preference indices (CPI_even/odd = 10.4 and 8.1 for the mine soils under pine and grass vegetation) reflect the increasing role of terrestrial vegetation in the formation of organic matter. The higher concentrations of the long-chain alkanes, fatty acids and alcohols are speculated as the reason for the severe and extreme water repellency observed with the Vertisol and the unreclaimed spoil. The presence of terrigenous steroid and triterpenoid markers in the RMSs is an indication of the ongoing soil formation processes. The analysis of lipid extracts allowed for the assessment of sensitive molecular indicators of biogenic terrigenous and coal origin and the degree of soil recovery following >20 years of spoils reclamation.     

Analysis of Fatty Acid Esters of Hydroxyl Fatty Acid in Selected Plant Food

Plant Foods for Human Nutrition - Metabolic syndrome, characterized by obesity, low-grade inflammation, insulin resistance, hyperglycemia, dyslipidemia and hypertension, is a major risk factor for...     

Interactions between floral morphology,position in cluster and 2,4-D treatments in three eggplant cultivars

The effects of treatments with 2,4-dichloro-phenoxy-acetic-acid (2,4-D), 2.5 mg l^?1, on the 4 different flower types in 3 eggplant cultivars with different flowering patterns were investigated. Varietal responses in fruit set were recorded, but fruit weight was increased considerably in all cultivars treated. Stylar heteromorphism affected fruit set more than did the position of the flower in the cluster. Changes in seed development, induced by environmental factors or by the 2,4-D treatments, were recorded and their relations to fruit development evaluated.     

Effects of different diurnal temperature combinations on fruit set of sweet pepper

Trials were carried out on sweet pepper, Capricum annuum L. cultivar ‘Ma'or’ under controlled temperature conditions and natural light. In the first trial, we examined night temperatures of 15, 18, 21 and 24°C (± 1) in combination with a day temperature of 24°C, and in the second trial day temperatures of 22, 25 and 28°C (12 hours) and divided day temperatures of 28-32-28°C (4+4+4 hours) in combination with a night temperature of 18°C. The highest fruit-set was obtained at the lowest night temperature; the highest night temperature caused considerable blossom drop. The highest tested day temperature did not cause increased blossom drop.     

Genetic analysis of Newcastle disease virus strains isolated in Bosnia-Herzegovina,Croatia, Slovenia and Yugoslavia,reveals the presence of only a single genotype,V, between 1979 and 2002

Newcastle disease (ND) epizootics in some European countries after the World War II were caused by ND virus (NDV) of multiple genotypes (IV-VIIa) occurring sequentially and/or simultaneously. This study was carried out to characterise the genetic composition of NDV strains during the outbreaks in the territory of the former Yugoslavia in order to enhance our understanding of the relationships of past epizootics in Europe. Sixty-eight NDV strains isolated between 1979 and 2002 were analysed by restriction enzyme digestion and partial sequencing of the fusion protein gene. All isolates were placed in genotype V, an exotic type, that was introduced to western Europe in 1970. Residue substitution analysis has allowed the recognition of four genetic variants, Vb1-Vb4, and the tracing of their movements. Vb1, a dominant variant in Bulgaria from the late 1970s, was also wide spread in the former Yugoslavia throughout the period under investigation. Vb2, a variant occurring in the neighbouring countries in the early 1970s could be the founder of the epidemic in Yugoslavia and it was present up to the late 1980s. Variants Vb3 and Vb4 could be found only after 1987. In conclusion, the ND outbreaks in Yugoslavia were part of the epizootic wave due to genotype V viruses that started in western Europe in 1970 and became endemic in the region. Inter-country transmission occurred for all variants, and Vb3 and Vb4 might have evolved during the endemic period.