The Influence of Cultivar Specificities and of Different Fertilizer Rates on Transpiration Intensity in Plum Leaves

Abstract

The paper presents two-year results (2001-2002) of a study on the influence of increasing rates of the fertilizer NPK 8:16:24 + MgO (I-400; II-600; III-800; IV-1000 kg/ha; V-control, fertilizer-free) on transpiration intensity. The trial included four plum cultivars ('Cacanska Lepotica', 'Cacanska Najbolja', 'Cacanska Rodna' and 'Stanley'). The samples were collected from mid-May to September under dry weather conditions, always at the same time of the day. Transpiration intensity was estimated by measuring the mass of the transpired water (Ivanov, 1950), and was expressed in mg of the transpired water per 1 g of fresh leaf mass for 1 h (mg g h(-1)). During the first year, leaves of the variant treated with the highest fertilizer rate (1000 kg/ha) exhibited the lowest (0.1332 mg g h(-1)) and the control the highest (0.1527 mg g h(-1)) transpiration intensity. As for the studied cultivars, the lowest transpiration intensity was found in cv. 'Stanley' (0.1234 mg g h(-1)), and the highest in cv. 'Cacanska Najbolja' (0.1661 mg g h(-1)). In the second year, the variant III gave the lowest transpiration intensity (0.1617 mg g h(-1)), whereas variant II displayed the highest values (0.1751 mg g h(-1)). Over the second year, leaves of cv. 'Stanley' had the lowest transpiration intensity (0.1396 mg g h(-1)), the highest being in cv. 'Cacanska Rodna' (0.1844 mg g h(-1)). Over the studied period, variant IV displayed the lowest leaf transpiration intensity (0.1499 mg g h(-1)), the highest being found in variant II (0.1605 mg g h(-1)) as well as in the control (0.1595 mg g h(-1)). Of all studied cultivars, cv. 'Stanley' had the lowest leaf transpiration intensity (0.1315 mg g h(-1)), while highest values were found in cv. 'Cacanska Najbolja' (0.1682 mg g h(-1)).