ISHS Acta Horticulturae 705: V International Walnut Symposium
DETERMINATION OF BLACK WALNUT (JUGLANS NIGRA) HARVEST DATE WITH DUROMETER MEASUREMENTS |
| Authors: | M.R. Warmund, M.V. Coggeshall |
| Keywords: | kernel color, nut quality, nut maturity, harvest parameters, maturity indices |
| Abstract:
A study was conducted to: 1) evaluate the use of a durometer for determining husk softening and the date of black walnut (Juglans nigra) harvest; and 2) elucidate the relationship between husk and kernel color, and date of harvest. Twenty nuts were randomly collected from ‘Football’, ‘Jackson’, ‘Sauber #1’, ‘Surprise’, and ‘Thomas’ trees on 25 Sept., and 1, 7, and 14 Oct. 2003. Husk hardness and color were recorded immediately after harvest. Nuts were then hulled within 48 hours and kernel color was assessed. Nuts were also evaluated by denting the husk at biweekly intervals to determine the optimum time of harvest, which is the method commonly used by growers. Results from the dent test indicated that the optimum time of harvest was 17 Sept. for ‘Sauber #1’, 23 Sept. for ‘Football’, 24 Sept. for ‘Jackson’, and 25 Sept. for ‘Surprise’ and ‘Thomas’. Husks of ‘Surprise’ and ‘Thomas’ nuts sampled on 25 Sept. and measured by the durometer had mean hardness values of 76 and 79, respectively. According to the dent test, ‘Sauber #1’ nuts were over mature and had a hardness value of 65 when measured by the durometer. By 7 Oct. and 14 Oct, mean husk hardness values of all cultivars were 59 and 47, respectively. As husks softened, their hue values also decreased. Color components (L*, hue, and chroma) of the kernels were not affected by harvest date. | |
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