ISHS Acta Horticulturae 803: VIII International Symposium on Modelling in Fruit Research and Orchard Management
THE INFLUENCE OF INCREASING AIR TEMPERATURES ON BUD BREAK DATE IN COMMON WALNUT (JUGLANS REGIA L.) |
| Authors: | A. Solar, M. Solar, Z. Črepinsek, F. Stampar |
| Keywords: | Juglans regia, cultivars, onset of bud burst, spring frost, phenological models |
| Abstract:
We determined how increased winter and spring air temperatures could affect walnut (Juglans regia L.) bud break date (BBD) in the late- and medium bud-break cultivars ‘Franquette’ and ‘G-139’. The period 1984–1990 (P1) with a mean air temperature (Jan-Apr) of 3.7°C was compared to the period 2000–2006 (P2) with a 4.6°C mean air temperature. Climatological data were collected by the Environmental Agency of Slovenia while the phenological data were recorded by the University of Ljubljana during long-term testing of foreign varieties. In P1, the mean BBD was April 23rd for ‘G-139’ and May 5th for ‘Franquette’. In P2, BBD was advanced by 3 days for ‘G-139’ and 7 days for ‘Franquette’. During both periods, BBD was strongly correlated to the average monthly air temperature (TMonth). In P1, TFeb and TMar had a stronger impact on BBD (r = between -0.53 and -0.75) than in P2, when BBD was more influenced by TJan (r = 0.75 for ‘G-139’ and 0.81 for ‘Franquette’). In’'Franquette’, BBD was also affected by TApr T (r = -0.84). Phenological models showed that the mean air temperature in the preceding one or two months (TMar and TApr) were important for predicting BBD. In the warmer time period (P2), TJan was also useful. | |
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