Yield Performance of New Macadamia Nut Selections in Kona, Hawaii

Macadamia nut (Macadamia integrifolia) is one of the most important agricultural commodities for the state of Hawaii with over 18,000 acres in production and a farm value of $35 million. Successful production of macadamia in Hawaii is related to the research and identification of high yielding selections that produce kernels with superior qualities.  At least 13 commercial cultivars have been developed in Hawaii, but 7 of these dominate the commercial plantings of macadamia in Hawaii.  Although other selections were identified as promising for superior kernel quality, tree shape, and pest resistance, none of these have been released to the public.  A field trial was established at the University of Hawaii Kainaliu Research Station in Kona (390m elevation), in July 2001 to evaluate 7 selections of macadamia nut based on kernel quality performance, including two commercially released selections ‘800’ and ‘344’.  Yield data were collected from 2010 to 2014 and quality data collection began in November 2015.  Year was significant for yield (kg/tree) (P<0.001) with yields increasing with tree age.  Selection also significantly affected yields (P<0.001), however there was no year by selection interaction.  The commercial selection ‘800’ yielded higher than four of the other selections (‘862’, ‘896’, 932’, and ‘344’) with average annual yields of 72 kg/tree.  Yields among the remaining selections (‘879’ and ‘344’) were not significantly different from the other selections.  The lowest yields were observed in ‘932’ with average annual yields of 36.6 kg/tree.  Initial quality data supports continued evaluation of these selections for the quality characteristics.  Kernel weights of the selections ranged from 2.8 to 3.37 g, within the recommended range of 2.5-3.2 g.  Kernel recovery also fell within the acceptable range of 38-48% for most of the selections.  One exception was selection ‘900’ which was very large (11.9 g nut weight) compared to the other selections (average of 8.1 g).  The kernel recovery rate of ‘900’ was 28% but the kernel weight was 3.37 g, suggesting an unusually thick shell on this selection.  The majority of the new selections yielded similarly to the commercial selections of ‘344’ and ‘800’.  While initial quality analysis suggests that many of these selections are of high quality with desirable traits, further quality analysis is needed to determine stability over time and space. Therefore, these selections should be evaluated in multiple locations to determine yield performance and quality under varying environmental conditions in Hawaii for release into the market.