The influence of flower morphology on pollination and yield of grapevine (Vitis vinifera L. cv. 'Pikolit')
2000
Rusjan, D. | Korosec-Koruza, Z., Tomazic, I. (Ljubljana Univ. (Slovenia). Biotechnical Fac., Agronomy Dept.)
Vitis vinifera L. cv. 'Pikolit' is a white grapevine variety, which production is generally very unstable and very poor. The vine express flower-shedding, which can be explained by several causes: physiological, pathological, genetic, ecological and nutritional. Flower-shedding has been studied at collection vineyard of Dobrovo in Goriska Brda. The variable studied was the impact of a different distance of cv. 'Pikolit' from a plantation of pollination vine cv. 'Rebula' on the quality and quantity of the crop. The grapevines have been divided into four groups; A (grapevines near pollinator), B (control grapevines), C (grapevines with isolation flowers) and pollinator group cv. 'Rebula'. The proximity of the pollination vine showed to be in direct correlation with the quality and quantity of cv. 'Pikolit' crop. The cause for this phenomena is a morphological one as cv. 'Pikolit' has functional female flower, which disable autofertilisation. Furthermore, the pollen itself is not fertile. In a two-year investigation conducted in Jablje the highest yield of red beet roots was obtained at transplanting and fertilisation with 150 to 200 kg/ha of nitrogen. Lower yield was reached at direct sowing and fertilisation with 200 to 250 kg/ha of nitrogen. At this level of yield the nitrate content in the red beet roots did not exceed the allowed quantity of 3000 mg/kg, which was the case at the fertilisation with 300 and 350 kg/ha of nitrogen. There was up to 7 times more nitrate in the leaf petiole than in the leaf lamina or in an undeveloped leaf; therefore, leaf petiole is the right part of the plant to determine the status of its nitrogen nutrition. Fertilisation with more than 200 kg/ha N can pollute the underground water with nitrates due to their washing out.
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