ISHS Acta Horticulturae 297: II International Symposium on Kiwifruit
THE DISTRIBUTION, ACCUMULATION AND FORM OF NITROGEN IN COMPONENTS OF THE KIWIFRUIT VINE THROUGHOUT THE SEASON |
| Authors: | C.J. Clark, G.S. Smith |
| Keywords: | amino acids, amides, N fertiliser |
| Abstract:
Six-year-old kiwifruit vines (Actinidia deliciosa) growing in a commercial orchard were destructively harvested at regular intervals over a year. At each harvest, component tissues of the perennial framework and annual growth were weighed and analysed for total-N, nitrate-N and free amino acids. At budbreak, the fine roots (<20 mm dia.) accounted for 56% of the N content of the perennial framework (291 g N per vine), followed by structural roots (>20 mm dia.) and leader. By harvest, net accumulation amounted to about 300 g N per vine, equivalent to that in the annual growth components. Arginine and glutamine were the predominant free amino acids in the perennial components throughout the year, while in annual growth, arginine, asparagine, glutamate and glutamine dominanted, depending on the time of year and type of tissue. Arginine, glutamine and nitrate were the main N-transport forms present in xylem sap vacuum-extracted from one-year-old canes; the former during dormancy, the latter two species during the period of vegetative growth. The uptake and distribution of N in vine components is discussed in relation to the timing and magnitude of input of N fertiliser. | |
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