Salinity and mineral nutrition effects on growth and accumulation of organic and Inorganic ions in two cultivated tomato varieties

A trial was conducted on the effect of salinity and method of fertilizer application on two varieties of cultivated tomato, i.e. VF 145 and Edkawi. Salinity ranged from 0.52 to 11 dS/m, and fertilizer was applied by either broadcasting in small doses or added with irrigation water. Weight of shoots, fruit yield, and sodium (Na), calcium (Ca), chloride (Cl), free proline contents in both developing and mature leaves, and total soluble salts and ascorbic acid contents in fruits were taken as evaluating criteria. Salinity depressed both growth and fruit yield, and simultaneously increased ion concentration in plant leaves. Sodium and Cl accumulated with salinity, being greater in mature leaves, while proline accumulation in developing leaves was much higher than in mature leaves. Total soluble salts and ascorbic acid were not affected. Liquid fertilization resulted in higher fruit yields than that obtained with the solid fertilizer treatments as well as better alleviating the depressive effects of salinity on plant growth and yield, especially at the lower salinity level where it was more beneficial to fruit yield. The VF 145 tomato variety was found a bit more sensitive to salinity than the Edkawi variety, and was affected differently by salinity, regarding both the yield and the pattern of organic and inorganic ion accumulation. Our results suggest that there exists a physiological mechanism that is involved in the salt tolerance difference observed between the two varieties that needs to be investigated.     

Survival of <Emphasis Type="Italic">Ralstonia solanacearum</Emphasis> in infected tissues of <Emphasis Type="Italic">Capsicum annuum</Emphasis> and in soils of the state of Pernambuco,Brazil

The survival of Ralstonia solanacearum A1-9^Rif race 1 phylotype I was studied in ten different soil types in the absence of the host plant as well as in infected tissues of the stem and root of bell peppers buried in the soil at 0, 5, and 15 cm. The survival time of R. solanacearum A1-9^Rif in the ten soil types ranged from 42 up to 77 days. Among the chemical and physical characteristics of the soil, clay content, residual moisture, and available water were positively correlated, and pH was negatively correlated, with survival time, population size at 42 days, and area under the population curve. The pathogen survival differed significantly in relation to the plant tissues, but not with respect to the incorporation depth of the infected tissues. The root tissue of bell pepper supported a larger bacterial population at 7 and 21 days (5 × 10⁴ and 3.1 × 10⁴ CFU g⁻¹ tissue, respectively) compared with the stem tissue (0.35 × 10⁴ and 0.48 × 10⁴ CFU g⁻¹ tissue, respectively) and also had a larger area under the population curve. On the other hand, the stem tissues presented a greater decomposition rate and pH compared with the roots. In conclusion, the different types of studied soils as well as the infected bell pepper tissues were considered potential primary sources of R. solanacearum inocula, but only for a short period.     

Natural regeneration of Pinus brutia Ten. in a recreational public forest in Zawita-Kurdistan region,Iraq

Zawita natural forest has recently has been subject to mass recreational activities during spring that have denuded large areas of the forest.It was thus essential to assess regeneration before designing optimizing strategies.To this end,we studied the overstory canopy and microhabitat conditions for recruitment of Pinus brutia Ten in 10 plots(20×25 m)on the southern aspects where the Zawita natural forest is still present.In total,1540 regenerating P.brutia were recorded,854 seedlings,597 saplings,and 89 trees.Seedlings and saplings were more frequent beyond the canopy than under the canopy of the parent trees.Regeneration requirements differed between seedlings and saplings.The probability of the occurrence of seedlings was negatively correlated with increasing litter depth and increasing soil compaction.The density of saplings only showed a positive significant correlation with increasing slope.The nearest neighbor index showed a trend toward a positive spatial association between understory shrubs with their neighboring seedlings at a mean distance of 1.6 m.Overall,the study highlighted the requirements for seedling regeneration as a relatively open canopy cover,a light understory litter layer,and noncompacted soils.These results are a step towards designing effective management and restoration programs.     

Synthesis of hydroxytyrosol, 2-hydroxyphenylacetic acid, and 3-hydroxyphenylacetic acid by differential conversion of tyrosol isomers using Serratia marcescens strain

We investigated to develop an effective procedure to produce the potentially high-added-value phenolic compounds through bioconversion of tyrosol isomers. A soil bacterium, designated Serratia marcescens strain, was isolated on the basis of its ability to grow on p-tyrosol (4-hydroxyphenylethanol) as a sole source of carbon and energy. During growth on p-tyrosol, Ser. marcescens strain was capable of promoting the formation of hydroxytyrosol. To achieve maximal hydroxytyrosol yield, the growth state of the culture utilized for p-tyrosol conversion as well as the amount of p-tyrosol that was treated were optimized. The optimal yield of hydroxytyrosol (80%) was obtained by Ser. marcescens growing cells after a 7-h incubation using 2 g/L of p-tyrosol added at the end of the exponential phase to a culture pregrown on 1 g/L of p-tyrosol. Furthermore, the substrate specificity of the developed biosynthesis was investigated using m-tyrosol (3-hydroxyphenylethanol) and o-tyrosol (2-hydroxyphenylethanol) as substrates. Ser. marcescens strain transformed completely m-tyrosol and o-tyrosol into 3-hydroxyphenylacetic acid and 2-hydroxyphenylacetic acid, respectively, via the oxidation of the side chain carbon of the treated substrates. This proposed procedure is an alternative approach to obtain hydroxytyrosol, 2-hydroxyphenylacetic acid, and 3-hydroxyphenylacetic acid in an environmentally friendly way which could encourage their use as alternatives in the search for replacement of synthetic food additives.     

Sugar-Starch Metabolism and Antioxidant Potential in Potato Tubers in Response to Different Antisprouting Agents During Storage

Single applications of different antisprouting agents like hot water treatment, spearmint oil and clove oil were carried out on potato cultivar “Lady Rosetta” to compare their efficacy with that of synthetic chloro isopropyl N-phenyl carbamate (CIPC). The tubers were stored at ambient storage conditions (25?±?2 °C) for 81 days to assess changes in their sugar-starch concentrations and antioxidant potential. Antioxidant potential in the tubers was assessed as their total phenolic concentrations and radical scavenging activities. In addition, the enzymatic activities were also determined in order to evaluate the possible depletion of these antioxidants as substrate during storage. Results revealed significant response of stored potatoes to all antisprouting agents compared with the control (P?≤?0.05). CIPC and clove oil applications maintained tuber dormancy almost twice as long (81 days) as observed in the control (45 days). Application of spearmint oil and hot water treatment maintained tuber dormancy for almost 2 months. However, it was associated with an increased percentage sprouting during the last weeks of storage. At the end of storage, the highest starch (16.83%) and lowest sugar (0.99%) concentrations were estimated after CIPC application and maximum total phenolic concentration (143.57 mg gallic acid equivalent (GAE)/100 g), and highest antioxidant activity (39.73%) were found after clove oil application. Enzymatic activities were not statistically different between CIPC and clove oil application during most of the storage period. Results showed that efficient replacement of CIPC with clove oil in the premium potato cultivar might be useful; this may avert related food safety and environmental issues and would also ensure organic potato storage.     

QTL hotspots in eggplant (Solanum melongena) detected with a high resolution map and CIM analysis

Fifty-eight F₂ individuals derived from an interspecific cross between cultivated eggplant, Solanum melongena, and its wild relative, S. linnaeanum, were phenotyped for 42 plant, leaf, flower, and fruit traits. Composite interval mapping analysis using genotypic data from 736 molecular markers revealed the positions of 71 statistically significant (P ≤ 0.05) quantitative trait loci (QTL) influencing 32 of the morphological traits. Although most QTL were location-specific, QTL governing three traits (leaf lobing, leaf prickles and prickle anthocyanin) were detected in both experimental locations. Analysis of three additional traits (stem prickles, fruit calyx prickles and fruit length) in both locations yielded QTL in similar but non-overlapping map positions. The majority (69 %) of the QTL corresponded closely with those detected in previous analyses of this data set. However the increased resolution of the linkage map combined with advances in QTL mapping permitted more precise localization, such that the average interval length of these QTL was reduced by 93 %. Thirty-one percent of the QTL were novel, suggesting that simple linear regression with a low density linkage map (the method used in previous studies of this population) missed a substantial portion of significant QTL. Hotspots of QTL affecting plant hairiness, prickliness, and pigmentation were identified on chromosomes 3, 6, and 10, respectively, and may reflect the pleiotropic activity of single structural or regulatory genes at these positions. Based on synteny between the eggplant, tomato, potato and pepper genomes, putative orthologs were identified for 35 % of the QTL suggesting strong conservation of gene function within the Solanaceae. These results should make it easier to target particular loci for map-based cloning and marker-assisted selection studies.     

Thiophanate-methyl sensitivity and fitness in Lasiodiplodia theobromae populations from papaya in Brazil

Stem-end rot, caused by Lasiodiplodia theobromae, is an important postharvest disease of papaya in Brazil. The use of fungicides is one of the main disease management measures. However, there are no data available on the sensitivity of L. theobromae to thiophanate methyl (methyl benzimidazole carbamate), the most common fungicide used in papaya orchards in northeastern Brazil. Thus, the effective concentration that results in 50 % of mycelial growth inhibition (EC₅₀) of 109 isolates, representing five populations of the pathogen was estimated in vitro. Seven components of fitness were measured for the 10 isolates with lower and high values of EC₅₀. Of the 109 isolates, 20.2 % were resistant to the fungicide with EC₅₀ values greater than 300 μg ml^?1, whereas the remaining 79.8 % were sensitive with an average EC₅₀ of 1.87 μg ml^?1. The EC₅₀ values for the resistant isolates were significantly (P?≤?0.05) higher than those for the sensitive isolates. When the fitness components were evaluated, only in relation to the spore production was significant difference among sensitive and resistant isolates, and resistant isolates showed sporulation capacity significantly lower than the S isolates, indicating a fitness cost.     

Physiological improvement in the copepod Eurytemora affinis through thermal and multi‐generational selection

As a major part of fish larval diet in nature, copepods constitute an appropriate live prey for aquaculture purposes. Considering the difficulty of mastering copepod mass production, studies on their growth performance at different environmental conditions are needed to improve their productivity. In this study a new selective approach based on temperature control is proposed to improve the physiological (body size, fecundity and lipid storage) performance of copepods. The estuarine copepod Eurytemora affinis known to have a high genetic variance in temperature tolerance was used as a biological model. First two different copepod lines were obtained after long‐term culture at constant cold (7°C) and warm (20°C) temperatures. Then both populations were transferred to a higher temperature of 24°C appropriate for aquaculture use and followed during five generations. During the first two generations (F1–F2) of a cold‐acclimated population, female body size and fecundity decreased significantly whereas the survival rate remained high. The high lipid content of this population was used by females to compensate the heat shock of more than 10°C. However, the survival rate decreased dramatically in F3 but allowed the selection of robust individuals which progressively improved their fitness during the following generations. So, compared to the warm acclimated population, the cold acclimated one showed larger body size, higher fecundity and better lipid storage. After only five generations at 24°C the cold‐acclimated population showed a significant genetic gain in prosome length compared to the warm acclimated one.