A Hybrid Artificial Intelligence Model for Aeneolamia varia (Hemiptera: Cercopidae) Populations in Sugarcane Crops

Sugarcane spittlebugs are considered important pests in sugarcane crops ranging from the southeastern United States to northern Argentina. To evaluate the effects of climate variables on adult populations of Aeneolamia varia (Fabricius) (Hemiptera: Cercopidae), a 3-yr monitoring study was carried out in sugarcane fields at week-long intervals during the rainy season (May to November 2005–2007). The resulting data were analyzed using the univariate Forest-Genetic method. The best predictive model explained 75.8% variability in physiological damage threshold. It predicted that the main climatic factors influencing the adult population would be, in order of importance, evaporation; evapotranspiration by 0.5; evapotranspiration, cloudiness at 2:00 p.m.; average sunshine and relative humidity at 8:00 a.m. The optimization of the predictive model established that the lower and upper limits of the climatic variables produced a threshold in the population development rate of 184 to 267 adult insects under the agroecological conditions of the study area. These results provide a new perspective on decision-making in the preventive management of A. varia adults in sugarcane crops.     

Biomonitoring and Sourcing Toxic Elements Using Vascular Epiphytes of the Tillandsia Genus in the Mining Region of Taxco de Alarcón,Guerrero, Southern Mexico

Water, Air, &; Soil Pollution - The concentration of As, Pb, Cd, Zn, Fe, Mn, and Cu and the Sr and Pb isotopic compositions were determined in four species of the vascular epiphyte Tillandsia...     

The Biological Activities and Chemical Composition of Pereskia Species (Cactaceae)—A Review

The exploration of nature as a source of sustainable, novel bioactive substances continues to grow as natural products play a significant role in the search for new therapeutic and agricultural agents. In this context, plants of the genus Pereskia (Cactaceae) have been studied for their biological activities, and are evolving as an interesting subject in the search for new, bioactive compounds. These species are commonly used as human foodstuffs and in traditional medicine to treat a variety of diseases. This review focuses on the bioactivity and chemical composition of the genus Pereskia, and aims to stimulate further studies on the chemistry and biological potential of the genus.     

Differential Growth Response and Minituber Production of Three Potato Cultivars Under Aeroponics and Greenhouse Bed Culture

We have evaluated and compared different methods and cultivars for the production of quality prebasic seed in potato. Two cultivation systems, aeroponics and greenhouse beds with a peat moss substrate, and three potato cultivars with different vegetative cycle, Agria, Monalisa and Zorba, were assayed. Plants in the aeroponic system showed increased growth and their vegetative cycle extended between 12 and 36 % compared to the plants cultivated in greenhouse beds. Flowering and tuberization dates, Absolute Growth Rates (AGR) during the period of 60 days after planting (DAP) and height presented a wide variation between cultivars. Zorba showed earlier flowering and tuberization, lower AGR and reached a minor height at 60 DAP. Instead the late season cultivar Agria showed later flowering and tuberization, presented higher AGR and reached an increased height at 60 DAP. The total tuber yield per plant was between 34 and 87 % higher in the aeroponic system, with a marked difference for the earlier cultivars Zorba and Monalisa. Tuber numbers increased between 60 and 80 %. Minituber production in aeroponics showed a better size distribution, with a reduction in the percentage of tubers smaller than 12 mm of between 33 and 86 %. In this soil-less culture system average tuber weight increased in Zorba and Monalisa over 60 % but was lower for Agria. Further studies are needed to optimize aeroponics system, which can be considered a high yield potato multiplication system, particularly for early or mid season potato cultivars that may produce best quality minitubers.     

Bacterial community structure and detection of putative plant growth-promoting rhizobacteria associated with plants grown in Chilean agro-ecosystems and undisturbed ecosystems

Soil microorganisms with phytase- and 1-aminocyclopropane-1-carboxylate (ACC) deaminase activities are widely studied as plant growth-promoting rhizobacteria (PGPR). Here, we explored the bacterial community structure and occurrence of putative PGPR in plants grown in agro-ecosystems and undisturbed ecosystems from northern, central, and southern Chile. Total rhizobacterial community structure was evaluated by denaturing gradient gel electrophoresis, and dominant bands present in diverse ecosystems were sequenced. Significant differences in total bacterial communities were shown with some bacterial orders (Enterobacteriales, Actinomycetales, and Rhizobiales) being highly similar to both ecosystems. Twenty-nine putative PGPR, showing phytate- and ACC-degrading activities and production of auxin, were selected from across the sites. Based on 16S rRNA gene sequencing, the putative PGPR were characterized as Enterobacteriales (Enterobacter, Serratia, Pantoea, Rahnella, Leclercia), Pseudomonas, and Bacillus, consistent with previously reported PGPR and endophytic bacteria. Beta-propeller phytase genes with similarity to Bacillus were also identified. PGPR from agro-ecosystems appeared to show higher auxin production compared to those from undisturbed ecosystems. This study demonstrates that putative PGPR are widely distributed across Chilean soils. Further understanding of their contribution to the growth and adaptation of plant hosts to local soil conditions may provide opportunity for development of new PGPR in Chilean agriculture.     

Environmental Fate of Trifluralin,Procymidone, and Chlorpyrifos in Small Horticultural Production Units in Argentina

A mesocosm experiment was established to evaluate the effect of two organic wastes: fermented sugar beet residue (SBR) and urban waste compost on the stimulation of plant growth, phytoaccumulation of heavy metals (HM) and soil biological quality and their possible use in phytostabilization tasks with native (Piptatherum miliaceum, Retama sphaerocarpa, Bituminaria bituminosa, Coronilla juncea and Anthyllis cytisoides) and non-native (Lolium perenne) plants in a heavy metal-contaminated semiarid soil. Except R. sphaerocarpa, SBR increased the contents of shoot N, P and K and shoot biomass of all plants. The percentage of mycorrhizal colonization was not affected by the organic amendments. The highest increase in dehydrogenase and β-glucosidase activities was recorded in SBR-amended P. miliaceum. SBR decreased toxic levels of HM in shoot of P. miliaceum, mainly decreasing Fe and Pb uptake to plants. This study pointed out that the SBR was the most effective amendment for enhancing the plant performance and for improving soil quality. The combination of SBR and P. miliaceum can be regarded the most effective strategy for being employed in phytostabilization projects of this contaminated site.     

Characterization of the Wx gene in diploid Aegilops species and its potential use in wheat breeding

Wx gene encodes for the granule-bound starch synthase I or waxy protein, which is the sole enzyme responsible for amylose synthesis in wheat seeds. The Aegilops species, which are related to wheat, could be important sources of variation in this gene. In addition to its role in starch quality, this gene has been used in phylogenetic studies of wheat. The current study evaluated the variability of Wx gene in seven diploid species of Aegilops genus and compared their nucleotide sequences with the wheat homeologous genes. Nineteen new Wx alleles were found in the seven species evaluated. The alleles detected in two species of the Sitopsis section, Ae. searsii and Ae. speltoides, were related to the Wx-B1 gene of wheat. Two more of the Sitopsis species did not appear to be associated with this genome, whereas the remaining species were related to the Wx-D1 gene of wheat. The results showed an important variation of the Wx gene present in the Aegilops genus, and the 19 new Wx alleles detected could enlarge the genetic pool of wheat.     

Genetic diversity assessment for Eugenia uniflora L., E. pyriformis Cambess., E. brasiliensis Lam. and E. francavilleana O. Berg neotropical tree species (Myrtaceae) with heterologous SSR markers

In this study, a set of nuclear microsatellite markers were transferred and characterized from two Myrtaceae sub-families to four neotropical Eugenia fruit tree species (E. uniflora L., E. pyriformis Cambess., E. brasiliensis Lam. and E. francavilleana O. Berg), which are neglected and underutilized foods of great ecological and potential economic value found in the Atlantic forest regions of South America. Leaf samples of mature E. uniflora, E. pyriformis, E. brasiliensis and E. francavilleana trees, which are popularly termed “pitanga”, “uvaia”, “grumixama” and “guamirim”, respectively, were collected from two areas greatly impacted by the agricultural practices of the sugar cane industry in the state of São Paulo in the southeastern region of Brazil. A total of 19 simple sequence repeat (SSR) markers from the Myrtaceae sub-families Leptospermoideae and Myrtoideae were tested, and 15 polymorphic heterologous SSR markers were identified. The expected heterozygosities for E. uniflora, E. pyriformis, E. brasiliensis and E. francavilleana were 0.64, 0.75, 0.54 and 0.71, respectively. These results suggest that these SSR markers may be useful for population genetic studies. A total of 4, 9, 11 and 4 heterologous SSR polymorphic markers for E. uniflora, E. pyriformis, E. brasiliensis and E. francavilleana, respectively, are now available for genetic diversity, gene flow and mating system analyses in these species.     

Soil microbiological properties and its stratification ratios for soil quality assessment under different cover crop management systems in a semiarid vineyard

In vineyards in Spain, tillage and semiarid Mediterranean climatic conditions accelerate organic matter loss from the soil. Cover crops are a conservation management practice that can provoke changes in soil quality which requires evaluation. Stratification ratios of soil properties such as soil organic C and labile C fractions have been proposed for the assessment of soil quality under different soil management systems. Our objective was to study the effect of different cover crop management on various soil parameters and their stratification ratios. We evaluated three different soil managements in a Typic Haploxerept from NE Spain: conventional tillage (CT); 5‐y continuous cover crop of resident vegetation (RV); and 4‐y continuous cover crop of Festuca longifolia Thuill., followed by 1‐y Bromus catharticus L. after resowing (BV). We monitored soil organic C, particulate organic C, water soluble C, potentially mineralizable N, microbial biomass C, β‐glucosidase and urease enzymatic activities, and water stable aggregates at 0–2.5, 2.5–5, 5–15, 15–25, and 25–45 cm soil depths. We calculated soil depth stratification ratios of those soil properties. Resident cover crop increased microbiological properties, labile C fractions, and aggregation with respect to conventional tillage at 0–2.5 and 2.5–5 cm soil depths. However, for Bromus cover crop the same soil properties were lower than for the resident cover crop at 0–2.5 cm depth. Stratification ratios of β‐glucosidase and urease enzymatic activities, and particulate organic C showed a higher sensitivity than other soil properties; therefore, they would be the best indicators for soil quality assessment in semiarid Mediterranean vineyards.