Sustainable production systems for organic apple production

Organic apples are often sold for fresh consumption and therefore have to obtain high quality requirements. The fruits must obtain the right size and be undamaged without important infections of pest and diseases. Apple scab causes brown or black spots on the fruits and severe infections can result in fruits not suitable for consumption. This disease causes big reduction in yield and quality in organic production. Copper is an effective fungicide to control diseases and is used in organic apple production in some European countries. Copper has not been permitted in Denmark the last 10 years and the European Union wants to reject it from the list of pesticides permitted in organic production. To improve the quality and yield in organic apple production, it is important to find the best culture techniques. Combinations of cultivars, nitrogen availability, rootstocks and planting distances are tried to prevent or reduce apple scab infections

Low nitrogen manuring increased yield in high-density organic apple production

Yield, fruit quality and infections of diseases are determined by many production factors in the orchard. Water and nutrition supply, the choice of rootstock, planting density and control of diseases and pest are decisive

Soil treatments and rootstocks for organic apple production

6 different soil treatments: Mechanical weeding to the middle of the alleyway, mechanical weeding using 3 different equipments Clemens, Humus and a dish harrow, Soil covering with wheat straw and natural vegetation were combined with 3 rootstocks: M9, J9 and M26 to find the best combination for the apple variety 'Retina'. The trees were planted in the winter 1997/1998, only sprayed at primary RIMpro warnings and drip irrigated. The tree growth, nutrient content of the leaves in august, yield and fruit quality were determined. The rootstock J9 had the highest yield and the biggest amount marketable fruit. Mechanical cleaning to the middle of the alleyways, tree row weed control using Humus or soil covering with straw gave the highest yield and marketable fruit. A one meter weeded strip in the tree row did not remove the competition of the clover grass alleyway. Natural vegetation (weed) in the tree row reduced the yield with more than 50 percent. There was a break down of the Vf resistance of 'Retina'

Temadag om økologisk kernefrugt

Temadag om økologisk kernefrugt med sidste nye forskning og rådgivning inden for udvalgte udfordringer i økologisk produktion af kernefrugt. Inspiration til at forbedre kvalitet og udbytte i økologiske frugtplantager

Fornuftig økonomi i markiser over øko-æbler

Det kan være en udmærket økonomi i at sætte markiser på over økologiske æbletræer og undlade sprøjtning. Men der følger også nogle usikkerheder med et markisesystem

Forskning i økologisk frugt og bær

Institut for Fødevarer, Aarhus Universitet råder over 8 ha til forskning i økologisk frugt og bær. Arealet indeholder forsøg med hindbær og brombær i tunnel, samt solbær og æbler

Økologisk æbledyrkning

Økologiske æbler sælges oftest til frisk konsum, hvilket betyder, at de skal leve op til høje kvalitetskrav. Frugterne skal opfylde størrelseskrav og være hele og sunde. Den værste skadevolder er æbleskurv. Skurv forårsager brune til sorte pletter på frugten og kan angribe så kraftigt, at æblerne bliver uegnede til spisning. Denne svampesygdom er årsag til meget stor nedgang i udbytte og kvalitet i økologisk produktion. Kobber er et effektivt middel mod svampesygdomme og bruges til økologisk æbleproduktion i de fleste europæiske lande. Det er dog ikke godkendt i Danmark, og der er udsigt til et totalt forbud i EU. For at forbedre kvaliteten og udbyttet i en økologiske æbleproduktion må man derfor finde den bedste kombination af kvælstofforbrug, grundstamme og planteafstand til at forebygge æbleskurvinfektioner og dermed forbedre frugtkvaliteten og produktiviteten

Follicular growth and atresia in the mare

The growth and atresia in equine follicles has received little attention although the mare is a unique model because of the size of the animal, the size of the ovarian follicles and the unusual ovarian anatomy. The size of the animal allows ultrasound scanning to monitor follicle dynamics in vivo and the size of each follicle allows for several parameters to be studied without having to pool follicles together and thereby potentially introducing errors. Several studies in the equine species have focused on follicle dynamics, others on atresia and follicular fluid hormone levels and yet others on the oocyte, but none have combined all of these areas. The aims of this thesis were to establish whether granulosa cells of regressing equine follicles degenerate via an apoptotic mechanism and whether the presence of apoptotic cell death in granulosa cells was correlated with other indices of follicle health such as steroid hormone levels and oocyte quality.At first each parameter was investigated in detail at a microscopic level: oocyte chromatin configuration, cumulus morphology, follicle wall atresia, granulosa cell apoptosis and steroid content in follicular fluid. Then followed a whole animal approach with monitoring of follicular growth via ultrasonography. In the end this information was put together when studying ovaries recovered at different stages of the cycle in order to reveal when selection took place and how this was reflected in the parameters of the individual follicle.The temperature at which the ovaries were held did not significantly affect (P > 0.05) chromatin configuration in oocytes (n = 73), but the length of time at which the ovaries were held, did significantly change chromatin configurations (n = 222) after 6 hours (P < 0.001). Health status of the follicle appeared to affect chromatin configuration (n = 118), but this failed to reach significance (P = 0.08). Oocyte chromatin configuration tended to change from even distribution within the germinal vesicle, through different degrees of condensation, to metaphase stages with increasing apoptosis or atresia of the follicle. The puzzling configuration condensed chromatin may be part of the normal development but may also be an end-stage chromatin configuration as it tended to be most frequent in atretic follicles and increased in frequency after long storage in the ovary. The relationship between cumulus morphology and chromatin configuration (n = 149) was evident: compact cumulus morphology was associated with immature oocyte chromatin configurations and fully expanded cumuli were correlated with metaphase chromatin (P < 0.001). Each sequential step of cumulus expansion represented a further step towards meiotic maturation.Evaluation of follicle health based on granulosa cell morphology immediately upon retrieval, follicular wall atresia and apoptosis showed that each of the methods to detect atresia and apoptosis had advantages and limitations and that it was necessary to use the methods in conjunction because they supplemented each other. Histological atresia and ethidium bromide detection of apoptosis (n = 20) was significantly correlated (P < 0.001), and the stereomicroscopic evaluation of freshly isolated granulosa cells were significantly correlated (P < 0.001) with the histological findings (n = 33). Apoptotic granulosa cells and theca cells were detected histologically, a phenomenon which has not previously been described in equine follicles.In a study with 293 follicles from 23 mares, it was found that apoptosis was not a definite measure of death, because growing follicles, as determined by ultrasonography, could be apoptotic and have no other signs of impending death of the follicle, although apoptosis generally was associated with atresia of the follicle (P < 0.001). There was a population of small, atretic follicles with expanded cumuli and oocytes with chromatin progressed towards meiosis, and a population of large, healthy follicles, with young oocyte configurations and no cumulus expansion, and finally a population of follicles larger than 30 mm, which were healthy, but had started to move towards maturation in vivo, i.e. getting ready for ovulation. Size of the follicle appeared to be more important than stage of cycle for predicting chromatin configuration, cumulus morphology and atresia and apoptosis, but size of follicle was correlated with stage of cycle. This led to the theory that despite the larger follicles having stopped growing according to the follicle maps made from ultrasound scans, regression may not initially be related to detectable apoptosis, and that overt apoptosis may be a later event. The fact that most atretic follicles were small suggested that follicles regressed and slowly became overtly atretic and contained low levels of oestradiol and degenerate oocytes surrounded by expanded cumuli.When used in combination with plasma hormone levels, daily mapping of follicles in 7 ponies and 5 mares throughout the cycle made it possible to detect days of changes in follicular growth both of the individual large follicle and smaller follicles in groups in relation to hormone changes. The growth of the largest follicle to a point where it was capable of producing sufficient oestradiol, resulted in decreasing levels of FSH. The IX decreasing levels of FSH caused the smaller follicles to regress. The increased oestradiol concentrations promoted increased LH production as well as partaking in luteolysis, with resulting further increased levels of LH due to lack of negative feed back from progesterone. When the inhibiting effect of oestradiol disappeared just before ovulation, FSH started to increase, resulting in growth of a new wave of follicles, emerging on day 6 (P < 0.01). Divergence in growth rates between the dominant follicle and the largest subordinate follicle happened on day 9 and this became significant on day 12 of the cycle (P < 0.05). At this point FSH levels were high, LH was low and progesterone was still produced. The cause of deviation in this study remains unknown. The subordinate follicles grew until day 17 - 18, at which point they started to regress. The follicle maps were a reliable method of determining growth and regression, when keeping in mind that there are influences from regressing, atretic follicles during periods of general growth and that monitoring of the individual small follicle is not possible when there are many follicles.In conclusion this thesis demonstrated that oocyte chromatin configuration, cumulus morphology, follicular fluid steroid concentration and granulosa cell health are parameters, which change with follicle health, and that ultrasound scanning is an important and necessary tool to use in conjunction with the above measurements when studying follicle growth, selection and regression. Death of follicles happens gradually, and selection for dominance is a gradual process, where one follicle gains advantage over the competitors, resulting in dominance at an early stage during the cycle