Fruit thinning in organic apple growing with optimized timing and combination strategies including (new) natural spray products and mechanical rope-devices

The aim of our study was to find new thinning methods for organic apple production able to fulfil the standards of Bio-Suisse, the main label organisation of the organic food sector in Switzerland. The 14 trials reported were carried out during flowering period in 2003 and 2004 on the cultivars Pinova, Gala, Maigold, Elstar, Golden Delicious and Otava at different sites. The results confirm the good efficiency of mechanical thinning with the rope thinner and the thinning potential of vinasse, a by-product of molasses. Different vinasse products were tested (K-Vinasse, light-vinasse, N-Vinasse) and it was observed that those containing less nitrogen had a minor thinning effect. To avoid phytotoxicity on leaves, the concentration of N-Vinasse should not exceed 10 %. It seems that for Gala higher concentrations are needed, 7.5-10%, whereas with Maigold the efficacy of N-Vinasse was the same with the 2.5 % concentration as with 5 % and 10 %. On the other hand, partly good results were obtained when N-Vinasse was over-concentrated to 12 %, applied at warm weather and rinsed with clear water 4-6 hours later to avoid the phyto-toxic effect (“burn & rinse” method). Corn Oil, a commercial product from New Zealand, gave encouraging results. Lime sul-phur didn’t effectuate a significantly better thinning effect. The best method tested (fruit set reduction by 44 % and 26 % higher flower bud set next year) was achieved with a combination of rope thinner and N-Vinasse: rope thinner to thin the peripheral branches and to exert a physiological stress; and N-Vinasse to thin the inner parts of the canopy that the ropes can’t reach. Other tested products did not show satisfying effects. Trials also confirmed the importance of applying these thinning agents at least two times, at the appropriate phenological stage of flowering period (F,) F2 (full bloom) and G (= F2 of the one-year old shoots). Hitting also the flowers of the one-year old shoots is important to break bi-annual bearing. Pollen tube growth was assessed by fluorescence microscopy. Almost complete inhibition of pollen tube germina-tion was observed with Lime Sulphur and over-concentrated N-Vinasse (12 %) whereas with N-Vinasse at 5 % inhibition was 50 % less compared to untreated styles. Some contradictory results between different trials we ascribe to the air temperature during and after the treatments. It seems that treatments with N-Vinasse should be carried out at warm and sunny days above 16, better 18-20 deg. C. to maximize phytotoxicity on the styles; whereas we recommend to apply the rope thinner during periods of cold and clouded weather to maximize the thinning effect due to physiological stress and shortage of assimilates to the fruitlets. Concrete practical recommendations are given

Factor graph based detection approach for high-mobility OFDM systems with large FFT modes

In this article, a novel detector design is proposed for orthogonal frequency division multiplexing (OFDM) systems over frequency selective and time varying channels. Namely, we focus on systems with large OFDM symbol lengths where design and complexity constraints have to be taken into account and many of the existing ICI reduction techniques can not be applied. We propose a factor graph (FG) based approach for maximum a posteriori (MAP) symbol detection which exploits the frequency diversity introduced by the ICI in the OFDM symbol. The proposed algorithm provides high diversity orders allowing to outperform the free-ICI performance in high-mobility scenarios with an inherent parallel structure suitable for large OFDM block sizes. The performance of the mentioned near-optimal detection strategy is analyzed over a general bit-interleaved coded modulation (BICM) system applying low-density parity-check (LDPC) codes. The inclusion of pilot symbols is also considered in order to analyze how they assist the detection process

Fruit Thinning in Organic Apple Growing with optimized Strategies including natural Spray Products and Rope-Devices

The aim of our study was to find new thinning methods for organic apple production able to fulfil the standards of Bio Suisse, the main label organisation of the organic food sector in Switzerland. The 17 trials reported were carried out during flowering period in the years 2003, 2004 and 2005 on the cultivars ‘Pinova’, ‘Gala’, ‘Maigold’, ‘Elstar’, ‘Breaburn’, ‘Golden Delicious’ and ‘Otava’ at different sites. The results confirm the good efficiency of mechanical thinning with the rope thinner and the thinning potential of vinasse, a by product of molasses. Different vinasse products were tested (K-Vinasse, light-vinasse, N Vinasse; NK-Vinasse) and it was observed that those containing less nitrogen had a minor thinning effect. To avoid phytotoxicity on leaves, the concentration of N-Vinasse should not exceed 10%. It seems that for ‘Gala’ higher concentrations are needed, 7.5-10%, whereas with ‘Maigold’ the efficacy of N-Vinasse was the same with the 2.5% concentration as with 5% and 10%. On the other hand, partly good results were obtained when N-Vinasse was over-concentrated to 12 or 15%, applied at warm weather and rinsed with clear water 4-6 hours later to avoid the phytotoxic effect (“burn & rinse” method). Corn Oil (5%), a commercial product from New Zealand, gave encouraging results. Lime sulphur (2%) did not effectuate a significantly better thinning effect. The best method tested with a fruit set reduction by 62% and 3,05 times higher flower bud set next year was achieved with a combination of rope thinner and N-Vinasse: rope thinner to thin the peripheral branches and to exert a physiological stress; and N-Vinasse to thin the inner parts of the canopy that the ropes can’t reach. Other tested products did not show satisfying effects. Trials also confirmed the importance of applying these thinning agents at least two times, at the appropriate phenological stage of flowering period mainly at F2 (full bloom) and G (= F2 of the one-year old shoots) and in case at F (king flower open). Hitting also the flowers of the one-year old shoots is important to break bi-annual bearing. Pollen tube growth was assessed by fluorescence microscopy. Almost complete inhibition of pollen tube germination was observed with Lime Sulphur and over concentrated N-Vinasse (12%%) whereas with N-Vinasse at 5%% inhibition was 50%% less compared to untreated styles.. Overlooking all trials, combining N-Vinasse and rope thinner was the most efficient strategy for flower thinning. However, after our trials, its efficacy seems to depend strongly on climatic conditions and phenological stages: treatments with N-Vinasse should be carried out at warm and sunny days above 16, better 18-20 deg. C. to maximize desiccation on the styles; whereas the rope thinner should be applied during periods of cold and clouded weather to maximize the thinning effect due to physiological stress and shortage of assimilates to the fruitlets