Effects of intra-vineyard variability and soil heterogeneity on vine performance,dry matter and nutrient partitioning

Three vigor zones, identified in a Barbera vineyard by remote sensing at full canopy, were carefully ground-truthed to determine, over 2 years, the relative weight of soil factors in affecting within-field variability, and to investigate vigor zone influence on dry matter (DM) and nutrient partitioning into different vine organs. Regardless of season, high vigor (HV) achieved stronger vine capacity as total vegetative growth and yield while resulting in markedly less ripened fruits than low vigor (LV) vines. PCA analysis carried out on ten different soil and vine variables clearly separated the three vigor levels and the correlation matrix highlighted that the factors mostly contributing to HV were soil depth, soil K and P concentration, total available water, clay fraction and N_leaf concentration. Conversely, sand fraction was the main marker for LV. When annual DM retrieved in clusters, canes, leaves, and shoot clippings was calculated for each vigor level and expressed as content (i.e. kg/ha) there was a general decreasing trend moving from HV to LV. However, when DM partitioned to each organ was given on a relative basis (i.e. percentage over total) results were similar across vigor levels. Similarly, when nutrients were given as content (e.g. kg or g/ha) out of 120 within-vigor combinations (12 nutrients, 2 seasons, 5 organs), 65 showed a significant difference between HV and LV. Conversely, with data expressed on a concentration basis (i.e. % DM) the number of significant differences between the vigor level means fell to 15. The study strengthens the causal link between soil properties and intra-vineyard spatial variability and clarifies that patterns of dry matter and nutrient partitioning to different vine organs are mildly affected by vine vigor when referred on a relative basis.

     

Evaluation of Bacillus spp. isolates as potential biocontrol agents against charcoal rot caused by Macrophomina phaseolina on common bean

The fungus Macrophomina phaseolina, the causal agent of charcoal rot of common beans, damages the roots, stems, and leaves of seedlings and plants and forms resistant structures, so that chemicals are not sufficient for disease control. Integrated management systems associated with the use of biological control techniques are a sustainable alternative. Here we collected 37 native bacterial isolates from the common bean rhizosphere and screened them for antagonistic activity against M. phaseolina. Four isolates (BA97, BN17, BN20, and BR20) identified as Bacillus spp. showed antagonism in vitro against M. phaseolina, inhibiting its growth by 62.5–85%. In an in planta antagonistic assay, isolate BN20 reduced disease severity the most. Isolates BA97, BN17, BN20, and BR20 produced volatile compounds as a mechanism of antagonism. They also produced indole acetic acid in vitro (1.98–3.87 μg/ml). These results suggest that seed bacterization with the rhizobacterial isolates for field planting may be an effective means to reduce crop damage by M. phaseolina.

     

Live weight estimation of donkeys in central Mexico from measurement of thoracic circumference

Body measurements (length from nape of neck to the withers; height to withers; length from withers to tail root; length from shoulder to tuber ischii; thoracic circumference; umbilical circumference) were taken and correlated with live weight from 160 donkeys (mean +/- standard deviation = 6 +/- 2.6 years old) in Central Mexico. The age was assessed from dentition. Sex of the donkeys was also recorded. Sex was an important factor of variation (p = 0.011). Live weight was estimated using two allometric models. Model 1: Live weight = beta x (thoracic circumference)beta1. Model 2: Live weight = betao x (height to the withers) beta1 x (thoracic circumference) beta2. Separate prediction equations were produced for males and females, plus one for the total sampled. The 'best fit' models, were those using thoracic circumference to predict the live weight. Males: live weight = 0.018576 x (thoracic circumference)1.84107 (R2 = 0.9839). Females: live weight = 0.031255 x (thoracic circumference)1.72888 (R2 = 0.9839). The equations derived to estimate the live weight of donkeys in Britain, Morocco and Zimbabwe were less satisfactory for use with donkeys from Central Mexico because they overestimated the live weight.     

Influence of Milk,Corn Starch,and Baking Conditions on the Starch Digestibility,Gelatinization, and Fracture Stress of Biscuits

Dough for nontraditional semisweet biscuits—prepared with wheat flour or replacing part of the wheat flour with corn starch, with or without skim milk—was baked at two oven temperatures, 120 or 170°C, until reaching moisture content and water activity lower than 6% and 0.5, respectively. Assays of fracture stress, differential scanning calorimetry, X‐ray diffraction, and starch digestibility were performed. Results showed that biscuits containing milk had the highest fracture stress, and biscuits baked at low temperature were harder than biscuits baked at high temperature. The degree of starch gelatinization during baking was higher when dough was baked at 170°C, compared with dough baked at 120°C. The decrease in gelatinization coincides with the decrease in the height and surface of peaks at 15 and 23° in the X‐ray diffraction patterns. Milk and corn starch did not affect the starch digestibility of biscuits, but biscuits baked at 170°C presented lower fracture stress and higher starch digestibility than biscuits baked at 120°C.     

Intra-specific DNA polymorphism in pineapple (<Emphasis Type="Italic">Ananas comosus</Emphasis> (L.) Merr.) assessed by AFLP markers

Pineapple (Ananas comosus (L.) Merr.) cultivars, often derived from somatic mutations, are propagated vegetatively. It has been suggested by isozyme data that there is little genetic variation among Smooth Cayenne cultivars. A thorough investigation of the genetic variation within the cultivated speciesAnanas comosus, particularly among commercial cultivars, will provide critical information needed for crop improvement and cultivar protection. One-hundred and forty-eight accessions ofA. comosus and 14 accessions of related species were evaluated with AFLP markers. The average genetic similarity ofA. comosus was 0.735 ranging from 0.549 to 0.972, suggesting a high degree of genetic variation within this species. With AFLP markers, discrete DNA fingerprints were detected for each commercial cultivar, breeding line, and intra-specific hybrid. Self-incompatibility, high levels of somatic mutation, and intraspecific hybridization may account for this high degree of variation. However, major cultivar groups of pineapple, such as Cayenne, Spanish, and Queen, could not be distinctively separated. These cultivar groups are based on morphological similarity, and the similar appearance can be caused by a few mutations that occurred on different genetic background. Our results suggest that there is abundant genetic variation within existing pineapple germplasm for selection, and discrete DNA fingerprinting patterns for commercial cultivars can be detected for cultivar protection. The genetic diversity and relationships of fourAnanas species are also discussed.     

CHARACTERIZATION OF THE PHYSIOLOGICAL RESPONSE OF THE HIGHLY-TOLERANT TOMATO CV. ‘PONCHO NEGRO’ TO SALINITY AND EXCESS BORON

The variety of tomato (Solanum lycopersicum) called ‘Poncho Negro’ by farmers represents an important source of genetic resources of agricultural interest, because it has managed to thrive at levels of salinity and excess B that other varieties of the same species find impossible. This work was conducted under controlled growth conditions in a greenhouse, evaluating and obtaining plant material that served for physiological, chemical, and biochemical determinations. Stress conditions were supplied by irrigation, using different concentrations of sodium chloride (NaCl; 75 and 150 mM) and excess boron (B; 5 and 20 mg L^?1). The rate of net carbon dioxide (CO₂) assimilation, the quantum efficiency of photosynthesis and the relative water content (RWC) were measured. In addition, B, sodium (Na⁺), potassium (K⁺), and calcium (Ca²⁺), soluble sugars, and proline were quantified. The results suggest that ‘Poncho Negro’ accumulated Na⁺ mainly in the roots, partly limiting its entry into the aerial parts. In addition, it should be noted that the interaction of B and salinity reduced the movement of Na⁺ to the leaves. The ability of cv. ‘Poncho Negro’ to minimize leaf Na⁺ accumulation, accumulate more leaf B than control plants, and maintain its K⁺ level, when grown with an excess of B, possibly allowed the observed increase in the rate of photosynthesis. In addition, these tomato plants used proline and soluble sugars as osmo-regulators under high-B and saline conditions. Under all stress conditions studied, this variety of tomato was able to regulate its water content, with RWC values of approximately 86%.     

Effect of 'Candidatus Liberibacter solanacearum' on fitness of its insect vector, Bactericera cockerelli (Hemiptera: Triozidae), on tomato

The potato/tomato psyllid, Bactericera cockerelli transmits the bacterium 'Candidatus Liberibacter solanacearum', also known as 'Ca. L. psyllaurous', which causes zebra chip disease in solanaceous crops. There have been no studies addressing the effect of the bacterial plant pathogen on the biology of its insect vector. We examined several life-history traits, including 7-day fecundity, hatching percentage, incubation time, nymphal survival percentage, nymphal development time, total development time, and sex-ratio of 'Ca. L. solanacearum'-positive and -negative psyllid isofemale lines on tomato, as well as adult mortality index of 'Ca. L. solanacearum'-positive and -negative insects. The only two life-history traits that differed between the 'Ca. L. solanacearum'-positive and -negative psyllid isofemale lines were 7-day fecundity and nymphal survival percentage, which were significantly lower in 'Ca. L. solanacearum'- positive lines. The symbiotic bacteria associated with both psyllid isofemale lines were similar, with the exception of 'Ca. L. solanacearum', which showed 100% infection in the 'Ca. L. solanacearum'-positive lines and was not detected in the negative psyllid lines. These results suggest that 'Ca. L. solanacearum' has a negative effect on population growth rate of its insect vector on tomato.     

Single-Layer Centrifugation Through Colloid Positively Modifies the Sperm Subpopulation Structure of Frozen–Thawed Stallion Spermatozoa

The present study attempted to select the subpopulation of stallion spermatozoa that best survived a conventional freezing and thawing procedure, using centrifugation of post-thawed semen samples through a single layer of a glycidoxypropyltrimethoxysilane-coated silica colloid with a species-specific formulation (Androcoll-E™). After freezing and thawing, four sperm subpopulations were identified, listed as FT1 to FT4. While subpopulations FT1 and FT2 were characterized by low sperm velocity, high velocities characterized the ones called FT3 and FT4. The single-layer centrifugation (SLC)-handled sperm sample was enriched in subpopulation FT3, reaching a proportion of 82.6% of the present spermatozoa, in contrast with the non-filtered control post-thawed semen, where this sperm subpopulation only accounted for 16.3% of the total. It is concluded that in the equine industry, the SLC is a practical, easy-to-perform approach to improve the quality of equine frozen–thawed semen samples.     

Paraneoplastic hypereosinophilia in a dog with intestinal T-cell lymphoma

A 9-year-old, intact male Doberman Pinscher was examined because of anorexia and weakness. Results of a CBC showed severe, microcytic, hypochromic anemia with mild eosinophilia (2944 cells/microL, reference interval 100-1250/microL) and thrombocytosis. Hypoferremia, hypoferritinemia, and a positive fecal occult blood test supported a diagnosis of iron deficiency anemia secondary to chronic intestinal hemorrhage. Abdominal ultrasound evaluation showed a thickened small intestinal loop, of which representative specimens were obtained during exploratory laparotomy. Histologically, the intestinal wall was infiltrated by a neoplastic population of large, round, lymphoid cells with vesicular chromatin, 1 or more prominent nucleoli, and a high number of mitotic figures. The cells were closely admixed with mature eosinophils, but were negative for metachromatic granules with toluidine blue. Immunohistochemically, tumor cells were positive for CD3, and negative for CD21, Pan B, and CD79a. A diagnosis of intestinal T-cell lymphoma was made. Chemotherapy was begun, with 30 mg/m;2 of doxorubicin administered intravenously every 3 weeks. Eosinophil concentration was 880/microL 2 weeks after surgery (on day 15 after presentation) but increased markedly to 62,914/microL on day 30, 62,400/microL on day 37, and 39,444/microL on day 58 after presentation. An association between hypereosinophilia and T-cell lymphoma is well established in human patients, in whom production of IL-5 by neoplastic T cells has been demonstrated. Hypereosinophilia has been reported only rarely with intestinal lymphoma in cats and horses, and with T-cell lymphoma in dogs.