Search

Copyright of Historia Agraria is the property of Historia Agraria and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In Mexico, in the last five years, there was a 189.50 to 13 219.84 hectares increase in sunflower crop surface under rainfed conditions. Particularly, in 2016, in the state of Guanajuato, approximately 450 hectares were planted. Cultivation under rainfed conditions requires planning including bioclimatic variables to reach the optimal crop yield and development. This work aims to identify bioclimatic potential areas for sunflower cultivation under rainfed conditions in Guanajuato. In autumn-winter 2016, 45 sunflower fields (distributed in eleven towns) were monitored and stratified. Crop yield associated to maximum and minimum temperature, relative humidity, solar radiation, precipitation and evapotranspiration were recorded. The data from fields with higher yield than 1.89 t/ha were used to generate polygons with a saturation of 56 abundance points, to calculate the potential distribution using the Maxent software, with 23 bioclimatic variables as predictors. The variables with the highest contribution percentage to the potential distribution were: average temperature of the driest quarter, altitude, moisture regime, and edaphic profile. The potential areas for sunflower cultivation had a surface of 317 028 hectares where the predominant climate is sub-humid warm, the annual mean temperature is 20 °C, the annual mean rainfall is 600 to 800 mm, and the altitude ranges from 500 to 1500 masl. [ABSTRACT FROM AUTHOR]

The present study was performed with the objective of determining whether the density of cutworms is affected by the type of predecessor crop and field environment. The effect of each particular predecessor crop was assayed on three paddocks selected in 2014 and another three in 2015. The evaluations were done on stubble from the following grain crops: earlysown soybean (ES), latesown soybean (LS), sunflower (S) and maize (M). Sampling was performed at both lowground and highground sites in each paddock for determination of the density of cutworms on five and ten 1 m2 subsamples collected in 2014 and 2015, respectively. Thirty cutworms were bred to adulthood each year for their identification. Such experimental assessment showed that Agrotis robusta was the predominant species. Analysis of variance for density of cutworms was performed following a factorial design considering predecessor crop, paddock environment and year as treatments. The three of these factors affected the density of cutworms and did not show interactions with each other. Observed density values of cutworms were 0.17, 0.4, 1.7 and 2.88 m-2 in M, S, LS and ES stubbles, respectively. Cutworm density was higher in 2014 and for lowground sites. These results allow the identification of predecessor crops and field environments holding different risk of damage by cutworms, contributing in that way to the development of more efficient sampling protocols and the integrated management for that kind of plague. [ABSTRACT FROM AUTHOR]

Studies were carried out, guided to compare the affectation by H. electellum to four sunflower cultivars and the establishing of relationships among the infestation and the affectations caused by H. electellum to sunflower in Cuba. In general the cultivars Caburé-15 and CIAP JE-94, showed more resistant to the attack than cultivars CGGI-90 and CGGI-611. The study not demonstrates statistically the existence of differences among the affectations to plants with seeds of different coloration, independently of cultivars. Was found that, under our cultivation conditions, a larva consumes an average between 1,24 g and 1,82 g of seeds during it development. An average infestation of one larva by plant, generates affectations to the yield of around 0,06 t/ha. [ABSTRACT FROM AUTHOR]