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

Thinning of Organic Apple Production with Potassic Soap and Calcium Polysulfide at the North of Spain.

Asturias, in the North West coast of Spain, is a region with old tradition at cultivation of apple and its transformation to cider. The production of apple is mainly done under traditional uses and semi-extensive or semi-intensive system and with local cultivars. Thinning strategy is little practiced and the biennial bearing cycle is one of the main problems for the farmers. The production of apple under organic techniques in Asturias is still limited but increasing. Since 2005, experiments have been conducted on several cultivars (‘Raxao’, ‘Xuanina’ and ‘Gold-Rush’) to evaluate the effects of Potassic Soap (with or without olive oil) and Calcium Polysulfide as thinning products. We present here the first promising results of these experiments. With different concentrations of both products we have increased the apple production of two cultivars for the period 2006- 2007. There were positive effects on the vegetative growth of the trees and on the quality of apples. In the spring 2007 we initiated new experiments with other cultivars (‘Durona de Tresali’, ‘Solarina’, ‘Raxao’, ‘Regona’) in order to confirm our results. The new experiments also include the comparison of their effects with those of commonly used chemical products and with those of manual thinning techniques

The floral biology of the olive: effect of flower number, type and distribution on fruitset

10 pages, 1 figure, 5 tables, 15 references.The effect of flower number and distribution on the fruiting behavior of various olive cultivars was studied over a period of 10 years. The number of staminate flowers within each cultivar had no significant effect on fruitset. Pre-bloom removal of up to 50% of the flowers did not affect fruitset. Variation in prebloom flower-removal position resulted in similar fruitset per inflorescence, whether flowers were removed along the inflorescence axis or from the distal half of each inflorescence. Removal of half of the inflorescences resulted in doubling the fruit set on the remaining ones, except in cv. Koronaiki which normally sets more than one fruit on most of its inflorescences. The distal fruitful inflorescence set more than one fruit (mostly two) on 70–80% of the shoots of various cultivars. In cv. Santa Caterina a clear increase in fruitset per shoot was observed when 80% of the flowers per inflorescence were removed. In this cultivar the lateral flowers were significantly more fruitful than the king flower. This however, was not the case with cv. Manzanillo.Peer reviewe

Metamitron replacing carbaryl in post bloom thinning of apple trees.

Carbaryl or the mixture of carbaryl with NAA (naphthalene acetic acid) or BA (benzyladenine) are the post-bloom chemical thinners most widely used in apple thinning in Brazil. The marketing restriction of carbaryl demands new options of apple post-bloom thinners, requiring the evaluation of others compounds for this purpose. Metamitron is one of the substances that may be used in chemical thinning of apples. Metamitron was evaluated at two concentrations, alone or in mixture with BA, in "MaxiGala", "Fuji Suprema" and "Fred Hough" apple cultivars. Applications of metamitron at 384 mg L-1 and at 768 mg L-1 in a mixture with BA, ranging from 40 mg L-1 to 80 mg L-1, sprayed on fruits with diameter ranging from 5 to 25 mm were compared ith the standard treatment and hand thinning. The experimental design was a randomized complete block with 4-6 repetitions of a single plant. The variables analyzed were: fruit set (%); percentage of floral clusters with 1, 2, 3, 4 or more fruits; fruit yield (kg); verage fruit fresh mass (g) and percentage of dropped fruit after thinning. Metamitron alone or in combination with BA reduced production per plant and significantly increased the fresh weight of fruits in all cultivars tested. Metamitron at 800 mg L-1 resulted in excessive fruit thinning, especially in ?MaxiGala? cultivar. Metamitron or metamitron + BA have potential to compose the program of chemical thinning of apple trees to replace carbaryl. Index terms: Plant growth regulators, concentration, fruit set, fruit production. O carbaryl ou a mistura de carbaryl com ANA (ácido naftaleno acético) ou BA (Benziladenina) são os produtos mais utilizados no raleio químico da macieira no Brasil. Com o cancelamento do registro do carbaryl como raleante de pós-floração, são necessárias novas alternativas, sendo importante testar diferentes raleantes com esta finalidade. Dentre as substâncias passíveis de utilização no raleio da macieira insere-se o metamitron. O objetivo deste estudo foi avaliar a resposta da aplicação de metamitron no raleio das macieiras ?Fuji Suprema?, ?MaxiGala? e ?Fred Hough?. O uso de metamitron foi testado em duas concentrações, só ou em mistura de tanque com BA, e comparado com BA e BA + etefom, em três cultivares de macieira: ?Maxigala?, ?Fuji Suprema? e ?Fred Hough?. Aplicações de 384 mg L-1 e 768 mg L-1 de metamitron em mistura com BA de 40 mg L-1 e 80 mg L-1 aplicado em frutos de 5 a 25 mm de diâmetro foram comparadas com ?tratamento-padrão? e raleio manual. Foi usado o delineamento experimental em blocos ao acaso com cinco a seis repetições. As variáveis analisadas foram: frutificação efetiva (%), percentagem de cachos florais com 1; 2; 3; 4 ou mais frutos por inflorescência, produção por planta (kg), número de frutos por planta, massa média dos frutos (g) e percentagem de queda de frutos após o raleio. O metamitron só, ou em combinação com BA, reduziu a produção por planta e aumentou a massa média dos frutos em todas as cultivares estudadas. Metamitron a 768 mg L-1 resultou em excessivo raleio, especialmente na ?MaxiGala?. Metamitron ou metamitron + BA tem potencial para compor o programa de raleio químico da macieira em substituição ao carbaryl. Termos para indexação: Regulador de crescimento, concentração, frutificação efetiva, produção

THE EFFECT OF THE FLORAL APPLICATION OF GIBBERELLIC ACID ON UNPOLLINATED INFLORESCENCES OF THE DATE PALM CULTIVAR ASSIANE (Phoenix dactylifera L.): A CASE STUDY OF FIGUIG OASIS, MOROCCO

The objective of the present study was to evaluate the effect of Gibberellic Acid in mitigate the phenomenon of parthenocarpy and improve the fruit set in the date palm cultivar Assiane at Figuig Oasis in Morocco. For this, four different concentrations of Gibberellic Acid (GA3) viz., 5, 50, 100, and 200 ppm were applied on unpollinated inflorescences in two phases. The first dose of GA3 is applied at the time of spadices burst while the second one is applied after the seven days of the first one. The results obtained from the study showed that the application of gibberellic acid on unpollinated female inflorescences had a significant effect on the removal of parthenocarpy which resulting in the higher normal-looking fruits with normal seed and by promoting the maturity of parthenocarpic fruits. In the case of rate of thinning, the application of GA3 @ 5-100 ppm enhanced the flower drop, while the application at higher concentration i.e. 200 ppm promotes the retention and development of flowers. Further, the analysis of the ripe fruits sugars content by high performance liquid chromatography (HPLC) suggests that the application of GA3 did not have any significant effect on the sugar content and these treatments are not significantly different from the fruits of pollinated flowers

Flower abscission and fruit set on table grapes (Vitis vinifera L.): unraveling physiological and molecular mechanisms

Doutoramento em Engenharia Agronómica - Instituto Superior de Agronomia - ULDespite the importance of grapevine (Vitis vinifera L.) as one of the most cultivated species, the molecular events occurring during the critical period of fruit set, are far from elucidated. Aiming at providing a new insight on flower-to-fruit transition and flower abscission regulation, transcriptomic (RNA-Seq) and metabolomic analyzes were performed in the inflorescences and vine physiological alterations were investigated. Regarding flower-to-fruit transition regulation the results showed involvement of nutrient transport regulation and alterations on carbohydrates, secondary and hormone metabolism. In particular, induction of indole-3-acetic acid accumulation and activation of ethylene and sugar signaling were hypothesized to induce bioactive gibberellins biosynthesis, stimulating cell division within inflorescences. Assays with gibberellic acid (GAc) spraying and reduction of light interception during bloom allowed to promote flower abscission and suggested that growth regulator application and C-starvation resulted in distinct effects on inflorescence metabolism. GAc response involved stimulation of photosynthetic and respiratory machinery, nucleotide biosynthesis and carbon metabolism. Conversely, shading repressed photosynthesis, induced carbon/nitrogen imbalance and comprehensive alterations on hormone-related pathways, resulting in repression of cell division and induction of senescence. Candidates as common pathways leading to abscission were putrescine catabolism regulation, auxin biosynthesis induction, gibberellin biosynthesis repression and ROS signaling/detoxification although often through changes on specific transcripts and metabolites levels. Aiming at optimizing thinning methods, mandatory on table grapes production for guarantee bunch quality, GAc spray and shading during bloom were tested in seedless and seeded cultivars growing under field and greenhouse conditions. 'Thompson Seedless' showed to be sensitive to both thinning methods resulting in increased flower drop and reduced bunch compactness, but only GAc spray enhanced berry quality. Both treatments induced flower abscission in 'Black Magic' growing in late cycle on greenhouse production system, whereas during early cycle, only shade enhanced flower drop, bunch aspect and berry quality, resulting in an effective thinning metho

The Response of Zigadenus fremontii to Variation in Fire Regime

California\u27s chaparral shrub communities are naturally exposed to dry-season fire. It could be reasoned that prescription burns set during the wet season by land managers would have more detrimental effects on plant regeneration than dry season fires because wet season burns are more likely to kill newly emergent seedlings and damage newly emerged leaves of mature plants. Six field sites with flowering Zigadenus fremontii, an herbaceous perennial geophyte common to chapparal and part of the post-fire bloom, were established at Henry W. Coe State Park in Nothern California. Three sites were part of the September 2007 Lick Wildfire and three were part of a February 2007 prescription burn. The sites were monitored for Z. fremontii regeneration over two years. Z. fremontii exposed to the prescription burn fared better than the wildfire plants, with inflorescence height being significantly higher in prescribed burn sites. Bulbs were transplanted into soil from the prescription burn, wildfire, and unburned area to determine differences in regeneration due to soil characteristics. There were no significant differences due to soil types, but only bulbs from the prescription burn sites had the ability to produce flowers in multiple years subsequent to fire. Differences in germination rates between seeds grown in soil from the wildfire, prescription burn, and unburned soil were investigated via a controlled germination experiment. There was a trend for increased germination in burned soils compared to unburned soils. The evidence from this study suggests that geophytes can benefit from fires set outside of the natural fire season of chaparral