Trials on Pacific oyster (<Emphasis Type="Italic">Crassostrea gigas</Emphasis> Thunberg) rearing in the middle Adriatic Sea by means of different trays

The aim of this study was to compare the growth of juvenile Pacific oysters (mean weight 2.22 g; mean length 26.8 mm) reared with the suspended technique using three different types of trays fixed to long lines at a mussel farm located in the middle Adriatic Sea. Growth, mortality rate and quality traits of oysters cultured in a new type of tray (EXP) were compared to those of specimens reared in conventional trays (CON) and in “poches” (POC). Culture density was fixed at 0.03 oysters cm⁻² in all the tray types. After 11 months of growth, oysters reared in all the tray types reached marketable size, weighing between 94.08 and 110 g without significant differences. Length (98.8–103.3 mm), width (61.1–70.5 mm) and height (31.6–34.1 mm) did not show significant variations. The condition index showed differences among EXP (93.17%) compared to CON (81%) and POC oysters (72.87%), and significant differences were found between those reared at the surface and the bottom, regardless of tray type. Concerning mortality, the EXP group (7.5%) recorded significantly smaller losses than CON (18.4%) trays and POC (31.6%).     

Effect of broomrape (Orobanche cumana Wallr.) on some agro-morphological and biochemical traits of Tunisian and some reference sunflower (Helianthus annuus L.) accessions

Journal of Plant Diseases and Protection - Orobanche cumana Wallr. is an important new problem for sunflower crop in Tunisia. Little information is available on the behavior of sunflower to O....     

Characterization of single nucleotide polymorphism in Tunisian grapevine genome and their potential for population genetics and evolutionary studies

In this study, two gene fragments corresponding to the VvMYBA1 and VvMYBA2 loci were sequenced on a sample of grapes including cultivated and wild accessions originating from Tunisia, Germany and France. A total of 42 SNPs were detected in the sequenced fragments giving an average of 1 SNP every 33 bp. High level of polymorphism was observed in the samples either in cultivated or wild accessions. Pattern of nucleotide diversity indicates a non departure from neutrality expectations for wild grapevine sample for gene VvMYBA1 and VvMYBA2 and for cultivated sample for gene VvMYBA1. However, a linkage to a selective sweep was revealed for cultivated grapevine gene pool in gene VvMYBA2. A genetic structure of the studied sample according to accession taxonomic status was revealed by the UPGMA clustering with a considerable overlap. This result was confirmed by significant but low genetic differentiation values between cultivated and wild sample. The number of migrants Nm based on sequence data information between Tunisian cultivars and Tunisian wild accessions showed a low level of gene flow between those germplasms. This finding indicates that Tunisian cultivars do not derive directly from local wild populations but could mostly correspond to imported materials introduced during historical times. However, the possibility that some cultivars derived from ancestral events of local domestication or cross hybridization with native wild plants was not completely excluded for Tunisian grapevine accessions.     

Variability of grain productivity and energy profile of maize (Zea mays L.) genotypes

The goal of the present work was to test if there is genetic variability between precocious and superprecocious cycle maize genotypes in terms of grain productivity and energy profile. Data from two separate experiments were used. An experiment was conducted with 36 precocious cycle genotypes and another experiment was conducted with 22 superprecocious cycle genotypes. The following variables were measured: grain productivity (PROD), ethereal extract (EE), starch (ST), amylose (AML), and nitrogen-corrected apparent metabolizable energy (AMEn). For all variables, basic statistics and analysis of variance was performed. For each experiment, the genotypic correlation matrix was calculated and the multicollinearity was evaluated. Then, the Mahalanobis generalized distance matrix was calculated, the clustering of the genotypes was performed and the averages of the groups formed were compared, separately for each experiment. There was genetic divergence between precocious genotypes, as well as between superprecocious genotypes, especially in terms of grain PROD, EE concentration, and AML concentration. Groups of more productive genotypes presented lower EE and higher AML grain concentrations. The results of the present study indicated that it is possible to plan crossings between groups of genotypes in terms of PROD, EE and AML, with the goal of maximizing heterosis.     

Planning and management modeling for treated wastewater usage

Due to urban growth, some agricultural lands have been replaced by residential, municipal, and industrial areas. In some cases the remaining agricultural land will not have enough water because of transfers from agriculture to M&I (municipal and industrial) users. Therefore, in many places, especially in arid and semi-arid regions, the use of treated wastewater as a reliable source of irrigation water has already been, or will be, considered in the future. Due to its unique characteristics, this new resource has many challenges that cannot be ignored, such as health issues, water quality, and long- and short-term effects on soils and crops. The study described herein considered the development of a new GIS-based model for planning and managing the reuse of treated wastewater for the irrigation of agricultural and green lands, considering various factors such as population and urban growth. The model is composed of several different modules, including an urban growth model. These modules are designed to help in the decision-making process for allocations of water resources to agricultural areas, considering factors such as crop types, crop pattern, water salinity, soil characteristics, pumping and conveyance costs, and also by comparing different management scenarios. Appropriate crops that can be grown with a specific water salinity and soil characteristics, proper water resources for each farm (according to pumping and conveyance costs, and analysis of water demand, and water supply) can be determined through the application of this model. The model can also rank agricultural areas and open spaces in and near an urban area according to their suitability for irrigated agriculture.     

Study of Genetic Diversity of Pear Genotypes and Cultivars (<Emphasis Type="Italic">Pyrus communis</Emphasis> L.) Using Inter<Emphasis Type="Italic">-</Emphasis>Simple Sequence Repeat Markers (ISSR)

ISSR molecular marker was used to investigate genetic diversity of ‘Dare Gazi’ genotypes of Mashhad Esteghlal orchard and its relationship with other commercial and native cultivars of pear. Among ‘Dare Gazi’ genotypes of Mashhad Esteghlal orchard 23 genotypes were selected base on difference in tree vigor, leaf color, shape and color of fruit and also 33 other commercial and native pear cultivars from Esteghlal orchard and other Mashhad commercial orchards were studied. A total number of 230 DNA fragments were obtained using 11 primers of which 225 were polymorphic. On average, each primer produced 20.9 bands. Dice similarity coefficient ranged from 0.27 (between ‘Dom Kaj’ and Asian pear) to 1 (between ‘Dare Gazi’ 1 and 2 genotypes). Sample cluster dendrogram indicated that 56 genotypes were divided into 12 distinct clusters. The dendogram generated on the principle of Unweight Pair Wise Method using Arithmetic Average (UPGMA) was constructed by Dice coefficient and the genotypes were grouped into 12 clusters. ‘Dare Gazi’ genotypes did not show 100% similarity due to seed propagation or mutation, as ‘Dare Gazi’ 3 and 18 genotypes had the lowest similarity coefficient (0.64). Asian pears were placed in a separate group from European pears. And ‘Dare Gazi’ genotypes from different orchards were grouped separately, but all of them are called as ‘Dare Gazi’ pear for convenience. ISSR molecular marker can well identify the genetic variability among genotypes and cultivars and found suitable for grouping them.     

Morphological,physiological and biochemical aspects of osmopriming-induced drought tolerance in lentil

Lentil (Lens culinaris Medik.) is an important grain legume crop, mostly grown in semi-arid environments and often faces intermittent drought spells during different growth stages, which severely hamper its yield. This study, comprising of three separate experiments, was conducted to evaluate the potential of seed priming with CaCl₂ in improving drought tolerance in lentil. In the first experiment, lentil seeds were hydroprimed (water) or osmoprimed with 0.5 and 1% CaCl₂; while non-primed seeds were taken as control. In the second and third experiments, lentil seeds were subjected to pre-optimized osmopriming (1% CaCl₂) and hydropriming followed by surface drying or re-drying of primed seeds to original weight. The first two experiments were conducted in petri plates, while, in experiment 3, seeds were planted in plastic pots containing peat moss, maintained at 75% water holding capacity (WHC; well-watered) or 50% WHC (water deficit). Hydropriming and osmopriming improved seed germination, seedling growth, biomass production, chlorophyll intensity, sugar accumulation and reduced the oxidative stress in lentil under water deficit. However, osmopriming (1% CaCl₂) was more effective than the hydropriming in improving the lentil growth, biomass production, Ca accumulation and sugar metabolism under both well-watered and water deficit conditions. Seed surface drying, after priming, was more beneficial in improving the lentil performance, under both well-watered and water deficit conditions, than re-drying to original weight. Osmopriming (1% CaCl₂) increased the seeding dry weight (67%), SPAD value (140%), leaf Ca concentration (56%), α-amylase activity (55%), total soluble sugars (48%) and reduced malanodialdehyde content (35.9%) and total antioxidant activity (29.2%) than un-primed seeds under water deficit. In conclusion, osmopriming improved the lentil performance under optimal and water deficit conditions through early and synchronized emergence, better sugar and Ca accumulation which reduced the oxidative damage and resulted in better seedling growth and biomass production.     

Post-harvest disorders and mineral composition of apple fruits as affected by pre-harvest calcium treatments

Abstract

The effect of pre-harvest calcium sprays, CaCl₂ and Ca (NO₃)_2, on apple (Malus domestica) N, P, K, Ca and Mg content, storability and incidence of physiological disorders (superficial scald, bitter pit, physiological spot) was studied using two cultivars, ‘Krameri Tuviõun’ and ‘Talvenauding’. In the first year calcium treatment did not reduce any physiological disorders or loss of marketable yield. In the second year calcium treatment reduced storage losses until four months after storage. Bitter pit in ‘Krameri Tuviõun’ was unaffected by calcium treatment, but physiological spot of ‘Krameri Tuviõun’ and superficial scald of ‘Talvenauding’ were reduced by calcium treatment in the second year. Both physiological disorders of 'Krameri Tuviõun’ correlated negatively with Mg and P content and Mg/Ca ratio in apples. Superficial scald of ‘Talvenauding’ correlated negatively with Ca content and positively with K/Ca ratio, N/Ca ratio and Mg/Ca ratio in fruits. The conclusion can be made that content of Ca and its ratios with other nutrients plays an important role in the development of superficial scald on ‘Talvenauding’ fruits, and increasing Ca content in fruit can therefore be recommended for improving post-harvest quality of this cultivar. Since bitter pit in 'Krameri Tuviõun’ was not reduced by calcium treatment, it would be worth trying other measures for this cultivar.     

Distribution and Contamination of Heavy Metal in the Coastal Sediments of Port Klang, Selangor, Malaysia

The coastal sediments of Port Klang in Malaysia were monitored from November 2009 to October 2010 to evaluate the spatial distribution of heavy metals As, Cu, Cd, Cr, Ni, Pb, Zn, Pb, Mn, Al and Fe. Sediment samples were collected from 21 stations, covering three subsidiary ports, namely West Port, North Port and South Port, at three-month intervals. The geo-accumulation index and the enrichment factor were estimated to assess contamination status based on background values. Additionally, the sediment quality guide was applied to evaluate the adverse biological effects of heavy metals. These results show that the concentrations of some metals, such as As, Cd and Pb were comparatively higher than the background values. This is considered a critical environmental issue for this region. Furthermore, the toxicity estimation indicates that living organisms have a high risk of As exposure. Spatial distribution maps of heavy metals would aid in the identification of pollution sources and vulnerable sites.     

Variation of the amino acid scores and of the nitrogen-to-protein conversion factors in barley grain as a function of nitrogen content as compared with wheat and rye

Barley grains (9 samples from 7 cultivars) with nitrogen contents (N) ranging from 1.45 to 4.01% of dry matter were analysed for their amino acid (AA) composition with high accuracy from six different hydrolysates per sample. AA levels in grain increased as linear functions ofN with correlation coefficients close to unity. A comparison with literature data confirmed that the AA composition of any grain sample of normal barley can be predicted from itsN for all phenotypes and genotypes. AAs in grain protein changed as hyperbolic functions ofN which increased for Phe, Pro and Glx but more or less strongly decreased for the other AAs. By plotting AA scores againstN, barley proteins were shown to be always richer than wheat and rye in Val and Phe + Tyr; sometimes richer than both other species forN<2 (Lys); 2.2 (Leu and Ile); 3.4 (Thr); sometimes intermediate to wheat and rye above the latterN values. They were also intermediate in sulphur AAs forN<1.9 and drastically poorer forN>1.9. However, they were richer than both other species in Trp forN>1.6. The hyperbolic variations of non-protein nitrogen and nitrogen-to-protein conversion factors were determined as a function ofN and also compared with those of wheat and rye.