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Physiological Disorders. Strawberry . University of Jordanand Crop harvesting and h Faculty of Agriculture Department of Horticulture andling crops
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Physiological Disorders Strawberry
University of Jordanand Crop harvesting and h • Faculty of Agriculture • Department of Horticulture andling crops • Prepare the student…Raed AL -Thedah • Presented to the . Dr. Nihad Alsmairat
Introduction • Physical and physiological disorders of strawberry plants are caused by plant responses to non-biological factors. Adverse weather events, improperly planted and poorly maintained transplants and interactions from fertilizers or pesticides can all cause plant disorders. It is important for the grower or field manager to know what these disorders look like and what can be done about them.
critical component of determining the cause of a physical and physiological disorder is to know what its distribution is in space and in time. Something appearing suddenly over the entire breadth of the field quite probably indicates a massive one off occurrence like a weather event not modulated by field management. Alternatively, something developing over a period of time and affecting plants in only one part of the field would indicate the introduction of an agent such as a harmful chemical which has affected plants variabl
Once the cause of a plant disorder has been determined, most field managers will want to take steps to correct it. Some physical and physiological disorders, such as damage from lightning strikes or hail, cannot be corrected by human intervention, but others such as damage from over-fertilization or under- watering can. This is why it is so very important for the grower or field manager to be able to identify the main characteristic of each disorder. It is essential to keep good records of field management practices and analyze soil and irrigation water prior to planting to avoid potential problems.
UNEVEN RIPENING • This condition is thought to develop when high temperatures occur during the fruit ripening stage affecting the enzymes that cause normal pigmentation in ripe fruit. Fruit which are exposed to high temperatures earlier in their development are not as susceptible as fruit exposed to cool temperatures early on. • The variety Cavendish is especially susceptible to this condition, where white shoulders and blotches occur on otherwise ripe fruit. Although fruit is ripe and sweet, colour does not develop on certain areas of the fruit.
SUNSCALD • Sunscald is caused by high temperatures and over-exposure of strawberry fruit to the sun. Symptoms are more common when hot sunny weather occurs after a prolonged period of cool cloudy weather. Symptoms appear on the upper side of fruit, near the calyx, just before ripening. The fruit becomes pale and mushy at first, eventually drying down to a distinct, firm, bleached lesion ranging in colour from pink to off-grey. Berries growing on the south or west side of rows, and those without adequate foliage canopy, are most susceptible. Some varieties are more susceptible than others.
POOR POLLINATION • Poor pollination can cause poor fruit set, low yields, and poorly developed or misshapen fruit. The fruit will usually exhibit smaller seeds in the deformed area compared to the surrounding healthy area of the fruit. • Poor weather conditions during bloom increase the likelihood of poor pollination. Powdery mildew can also cause small fruit with small undeveloped seeds. Diseases such as powdery mildew can infect pollen and also lead to symptoms of poor pollination. • Growers should take care when using insecticides harmful to bees, especially during bloom.
POOR POLLINATION Strawberry
Nutritional Disorders • Calcium Deficiency • Balanced nutrition is important for strawberry plants to ensure optimal growth, yield potential, good quality fruit, and the ability to withstand disease and pest pressure. Excessive or insufficient supply of nutrients can lead to a variety of plant health issues.
Nutritional Disorders • Albinism in strawberry is nearly always associated with an excess of nitrogen fertility. Albino fruit of strawberry is a mottled white and is insipid and tasteless in flavor. Certain varieties seem to get albino fruit more often than others. During the production season, periods of warm weather followed by overcast and foggy skies are particularly favorable for albino fruit. Another cause of albinism can be the use of excess nitrogen. Once there is a change in the weather or throttling down on the quantity of nitrogen, albino fruit disappear.
recapitulation • Physiological Disorders: Perhaps because of rapid marketing and very short storage, few physiological disorders occur after harvest. CO2 injury, particularly when > 15% CO2 is used, is manifested as a bluing of the skin (Ke et al., 1991), whitening of inner fruit tissues (Gil et al., 1997), and fermentative off-flavors.
recapitulation • Suitability as Fresh-cut Product: Strawberries are suitable, and slices have a shelf-life of about 7 days at 2.5 °C (36.5 °F) and 5 days at 5 °C (41 °F) (Rosen and Kader, 1989; Wright and Kader, 1997).
References • http://postharvest.ucdavis.edu-1 • http://www.uckac.edu/postharv
