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Solomakhin A.,University of Bonn | Blanke M.,University of Bonn | Blanke M.,All Russia Michurin Research Institute of Horticulture
Annals of Applied Biology | Year: 2010

The purpose of this study was to investigate supposedly positive biological effects of coloured hailnets on microclimate, including photosynthetically active radiation (PAR), UV-B, air, soil, fruit and leaf temperature as well as humidity, which in turn may affect leaf anatomy, tree growth and fruit quality; apple was chosen as a model crop at Klein-Altendorf near Bonn, Germany; adjacent uncovered trees served as control. Red and green hailnets transmitted 3-6% more red or green light, without alteration of the red:far red (R-666 nm:FR-730 nm) ratio (0.99-1.01:1) and hence without affecting the phytochrome system. The microclimate was changed with a reduction by 12-23% in PAR and, to a larger extent, by 20-28% in UV, viz. shading. Light measurements at a 45° angle, to mimic the fruit or leaf position, showed that PAR was 90-210 μmol m -2 s-1 larger outside on a sunny summer day than under the white or red-white and 150-340 μmol m-2 s-1 larger than under red-black and green-black hailnets. Air temperature and relative humidity under coloured hailnets decreased by ca. 1.3°C and by ca 2% rh (cloudy) to 5% rh (sunny day), respectively, compared with outside; leaf temperature was decreased by up to 3°C and fruit temperature by up to 6°C. Soil temperatures at 5 cm depth were 0.5-1°C colder under red-black and green-black hailnets, but up to 0.9°C warmer under white and red-white hailnets compared with the uncovered control outside. Alternate bearing had a larger impact on vegetative growth in the affected year than the coloured hailnets; annual trunk diameter increments in cv. 'Fuji', i.e. the variety susceptible to alternate bearing, showed a larger variation than cv. 'Pinova' without alternate bearing. Reproductive growth, viz. return bloom and leaf anatomy were impaired by the coloured hailnets. Apple trees under dark hailnets developed thinner leaves with a thinner epidermis and fewer layers of palisade cells. These leaves were 3.5°C (dark hailnets) and 2.5°C (white hailnets) cooler than outside on a sunny day compared with ca. 1.5°C (dark hailnets) and 0.85°C (white hailnets) on a cloudy day. Transpirational cooling of cv. 'Fuji' leaves was 0.3-0.6°C outside and 1.4-1.6°C under the green-black hailnet on sunny days compared to <0.1°C on cloudy days. As a practical application, apple fruit colouration was dependent on light (PAR and UV-B) transmission of the respective hailnet colour. © 2010 Association of Applied Biologists. Source


Solomakhin A.A.,All Russia Michurin Research Institute of Horticulture | Trunov Y.V.,All Russia Michurin Research Institute of Horticulture | Blanke M.,University of Bonn
Acta Horticulturae | Year: 2011

In the light of a range of supposedly positive physiological effects, the purpose of this study was to investigate these environmental effects of coloured hailnets (green-black, red-black, green-white, red-white, grey, black and white hailnets) on light conditions beneath them which may affect leaf anatomy, tree growth and fruit quality in an apple orchard located at Klein-Altendorf near Bonn, Germany; uncovered trees served as control. Coloured hailnets did not considerably affect the spectrum of transmitted light which implied no changes in R:FR ratio and, consequently, did not influence the phytochrome system. Coloured hailnets transmitted 72-80% of incoming UV-B and 74-89% of PAR depending on hail net colour and caused surface temperatures to drop by 3-16°C with fruit and by 3.3-3.6°C with leaves. All this led to impaired fruit red (top) colour development in the order of the PAR and UV-B transmission through particular hailnet. Leaves without coloured hailnet were thicker with more palisade layers and thicker epidermis. Reproductive growth (return bloom) and leaf anatomy were impaired by the coloured hailnets without considerable impact on vegetative growth (trunk diameter). Source


Solomakhin A.A.,All Russia Michurin Research Institute of Horticulture | Trunov Y.V.,All Russia Michurin Research Institute of Horticulture | Blanke M.,University of Bonn | Noga G.,University of Bonn
Acta Horticulturae | Year: 2012

The aim of our study was to mechanically thin apple flowers without use of chemicals in orchard biosystems. The objectives were to remove, on average, one flower per cluster and concomitantly minimise any leaf damage, to improve fruit quality, to reduce hand thinning and overcome alternate bearing. The constructed device had three adjustable horizontal rotors with vertically rotating brushes. Apple trees grafted on M.9 rootstock were mechanically thinned at blooming with 300-420 rpm rotation and 5 or 7.5 km/h vehicle speed; adjacent untreated and manually thinned apple trees of the same rows served as controls. Mechanical thinning resulted in better fruit quality viz increased soluble solids (taste), acidity, fruit size, fruit with advanced ripeness, and additionally better red fruit colouration, associated with a higher (healthy) anthocyanin and chlorophyll content. The best engineering results were obtained with 360 rpm with both 5 km/h and 7.5 km/h vehicle speeds, a compromise between minimal tree damage and sufficiently reduced fruit crop of good quality including colour and taste as well as fruit size. Source


Solomakhin A.A.,All Russia Michurin Research Institute of Horticulture | Trunov Y.V.,All Russia Michurin Research Institute of Horticulture | Blanke M.,University of Bonn | Noga G.,University of Bonn
Acta Horticulturae | Year: 2012

The objective of this study was to examine organic mulches as an alternative for herbicides in organic fruit orchards, in order to improve yield, fruit quality and soil properties. In March 2002, the 1-1.2 m wide apple tree rows at Michurin Research Institute of Horticulture were mulched with sawdust or pine bark at ca. 25-30 t dry matter (DM) ha-1 or grass clippings, with between-tree herbicide (glyphosate) and/or manual weeding serving as control treatment. Grass alleyways in all the treatments were regularly mowed. Over the 4 years of the experiment, the herbicide-treated control reduced the weed cover to 2-25% and their dry mass to 3-27%, compared with the manual-weeded control values. The three organic mulches decreased the number of emerged weeds to 5-30%, compared with the manual-weeded control and was comprised of 25-30 weed species (making organic mulches an ecological alternative to herbicide). The three organic mulches improved soil properties, conserved soil moisture and increased N, P, and K content, compared with manual weeding. Apple trees with mulch developed a shallower root system. The three organic mulches, compared with manual weeding, enhanced vegetative growth, measured as length of one-year shoots, leaf area for leaves taken from bourse shoots (by 27 versus 12%) and tree trunk cross-section area (by 23 versus 13%). With the mulches, yield and fruit mass were increased by 35 and 17% compared with manual weeding. Source


Solomakhin A.A.,All Russia Michurin Research Institute of Horticulture | Trunov Y.V.,All Russia Michurin Research Institute of Horticulture | Blanke M.,University of Bonn | Noga G.,University of Bonn
Acta Horticulturae | Year: 2012

The objective of this study was to examine organic mulch (pine sawdust) as an alternative for conventional herbicides in fruit orchards in order to improve fruit quality. Light (PAR) reflection from the sawdust mulch was up to 2.5-fold increased. The peel of fruits from apple trees with mulched row stripes contained more phosphorus, magnesium and calcium (of importance for storability and shelf-life), as well as 16-250% higher phenolic content, including catechin and flavonols, compared to the herbicide treatment. Fruit from cultivars 'Krasivoye' and 'Gigulevskoye' with medium vitamin C content (usually around ca. 30 mg/100 g FM peel), was increased by organic mulches by 22 and 63%, respectively, but not in the cultivar 'Bogatir' with a large inherent vitamin C content, usually around 50 mg/ 100 g FM fruit peel. Thus, organic mulching enhanced the anti-oxidant content correlated with red colouration of the fruit skin in all cultivars examined, as a consequence of increased light (PAR) reflection from the mulch. Source

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