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Nyomora, A.M., Brown, P.H. and Krueger, B., 1999. Rate and time of boron application increase almond productivity and tissue boron concentration. HortScience, 34(2), pp.242-245. |
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Previous studies with tree species have demonstrated that foliar boron (B)
promotes flowering, fruit set, and yield. However, for most species the optimum time for
foliar B application has not been determined. This investigation was undertaken to study
the effects of time and rate of B application on almond [Prunus dulcis (Mill D.A.Webb)]
tissue B concentration, fruit set, and yield. Solubor (Na2B8O13.4H2O), a commercial
product containing 20.5% B, was applied with a handgun sprayer either in September (3
weeks postharvest), December (dormancy), or February (budbreak) at rates of 0, 0.8, and
1.7 kg·ha–1 B to almond cv. Butte at one site (Parlier, Fresno County, Calif.), and of 0, 0.8,
1.25, 1.7, and 2.1 kg·ha–1 B on the same cultivar in August, September, or February at a
second site (Orland, Glenn County, Calif.) using Borosol, a polyboronated commercial
product containing 10% B. At site 1, September application was more effective in
increasing tissue B concentration, fruit set, and yield than were December or February
applications. The optimal rate was 0.8 to 1.7 kg·ha–1 B when applied in September. At site
2, application in 1996 and 1997 increased tissue B concentration almost linearly, especially
when applied in August and February. Application at the highest rate (2.1 kg·ha–1 B) in
September produced the greatest final fruit set and yield in 1996. February applications
increased initial fruit set at both sites but were less effective than September applications
in increasing yield. Application of B did not affect any yield variable in 1997. These results
suggest that B should be applied immediately postharvest (September) for optimal effect
on tissue B concentration, fruit set, and yield in almond |
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