The impact of fruit temperature dynamics on heat stress tolerance of selected oil pumpkin genotypes

Fruit temperature is a key parameter for fruit growth and quality which is affected by climate, plant vigorousity, solar exposure and fruit thermal properties. In the present study, the variability in temperature dynamics of Styrian oil pumpkin fruits and selected interspecific hybrids involving Cucurbita argyrosperma, C. moschata, C. pepo was analysed in two different periods of hot weather. The temperatures were measured with thermistors on (a) attached fruits, (b) detached fruits exposed to the sun and (c) artificially black coloured fruits. The highest average temperatures were determined in the Styrian oil pumpkin, whereas the lowest temperatures were determined in genotypes with lighter fruit exteriors suggesting that those are less sensitive to heat stress conditions and may represent a good option for the improvements of adaptability to climatic changes. In order to combine lighter and harder pericarp, the most promising genotypes were crossed with wild Cucurbita okeechobeensis. The histological analysis showed that C. okeechobeensis was a good source of genes for obtaining a thicker sclerenchymatic layer within pericar

Possible application of differential global positioning system (DGPS) to harvesting date and precision viticulture

From 2004 to 2008, the maturity of grapevine (Vitis vinifera L.) was researched on the basis of sugar content and total titratable acidity at six locations with an undulating topography in three varieties: 'Chardonnay', 'Riesling' and 'Sauvignon'. All sampling points were geo-referenced simultaneously with differential global positioning system (DGPS) for creating sugar maps. The significant influence of the varying altitude above sea level (from 389 to 462 m) on the concentration of total sugar and the total titratable acidity of grapes were estimated during the ripeness of vine berry from July to September. The results of a five-year study proved that significant improvement of the grapes quality is possible by creating site-specific maps, which enable separate begging of harvest according to the different sea level.Key words: Vineyard, sugar map, GIS, DGPS

Automated Crop Yield Estimation for Apple Orchards

Abstract Crop yield estimation is an important task in apple orchard management. The current manual sampling-based yield estimation is time-consuming, labor-intensive and inaccurate. To deal with this challenge, we developed a computer vision-based system for automated, rapid and accurate yield estimation. The system uses a two-camera stereo rig for image acquisition. It works at nighttime with controlled artificial lighting to reduce the variance of natural illumination. An autonomous orchard vehicle is used as the support platform for automated data collection. The system scans both sides of each tree row in orchards. A computer vision algorithm detects and registers apples from acquired sequential images, and then generates apple counts as crop yield estimation. We deployed the yield estimation system in Washington state in September, 2011. The results show that the system works well with both red and green apples in the tall-spindle planting system. The crop yield estimation errors are-3.2 % for a red apple block with about 480 trees, and 1.2 % for a green apple block with about 670 trees.