research – Page 2 – Hazelnut Growers' Association of New Zealand

International hazelnut quality characteristics

Niels Maness – Department of Horticulture, Oklahoma State University

HGA newsletter, June 2006

Quality Characteristics and Criteria

In-shell hazelnuts should be properly sized to meet the stated market type and should be properly filled with at least 50% of the shell cavity occupied by nutmeat. Shells should be free of cracks and noticeable mechanical injury, clean, brightly colored and coloring patterns should be characteristic of the stated variety. The pellicle should be smooth and devoid of husk attachments. Kernels should meet the stated market type, be free of any misshapen or underdeveloped kernels and be free of any shell or foreign material and off-odor, off-flavor or mold. Water content of kernels should not exceed 6% if shelled or 7% if in-shell, and the total water content of unshelled nuts should not exceed 10 to 12%. Size is specified with grade as a determinant of quality, and minimum sizes are used for specification of classes “Extra” and “Class I” in international trade. For in-shell markets, larger and particularly rounded types are preferred. Shelled markets accommodate both rounded and oblong types, and size preference is dependent on the intended end use.

The mechanics of pollination

HGA newsletter, June 2004

Bryan Thomas recently attended two lectures given by Professor Karl Niklas who is a visiting Erskine fellow at the University of Canterbury. He is the Liberty Hyde Bailey Professor of Plant Biology at Cornell University. The subjects of his lectures were “Allometry of plant growth” and “The Biomechanics of Wind Pollination”.

The Biometrics of Wind Pollination

In this lecture Professor Niklas demonstrated his work on airflow around female wind pollinated flower structures and how the shape influences the airflow, and the consequences for successful pollination. Using pine trees as the prime example he carried out wind tunnel tests on receptive pinecones and plotted the course of both neutrally buoyant bubbles and actual pollen grains around the cone. The cones were surprisingly efficient at trapping pollen grains in eddies circulating around and through the cones and that, by placing the actual flower deep within the cone in an apparently inaccessible position, the chance of a pollen grain landing in the right place was enhanced.

Murray Redpath

HGA newsletter, January 2004

In this issue Murray Redpath of “Wairata Hazels”, near Opotiki, is sharing some of his vast experience of Hazelnut growing with us.

Wairata Hazels is part of Wairata Forest Farm, a 575 hectare property in the hills of the Eastern Bay of Plenty.

Historically the property has been run as a sheep and cattle farm with occasional income from wild animals (deer, opossums), tourism, and forest products (primarily native timber).

One in 8000!

From ‘Sun-Diamond Grower’, written by Jamie K. Hartshorn

HGA newsletter, January 2004

That’s about how many hazelnut seedlings Oregon plant breeders must go through before one is worthy of release.

It pays to be patient if you’re a plant breeder. Take scientists at Oregon State University’s Agricultural Experiment Station for instance. Their quest for a new hazelnut variety for the kernel market took some 17 years from initial trials to final release. Many thousands of seedlings later, along came ‘Willamette’, introduced in 1990. “The new variety has shown both positive and negative points,” says Dr. Shawn Mehlenbacher, associate professor and plant breeder with OSU’s Hazelnut Breeding Program. The largest planting to date is a 40 acre block that went in last Spring, “but most growers are taking a wait and see attitude,” he says.

Pollenizer management in a hazelnut orchard

S.A. Mehlenbacher and A.N. Miller – Oregon State University, 1988

HGA newsletter, Winter 2003

Three factors must be considered in choosing pollinizer cultivars: 1) the amount of viable pollen produced, 2) compatibility, and 3) time of pollen shed.

The amount of viable pollen produced by a hazelnut tree is largely a function of the number of catkins on the tree and the viability of the pollen produced. Some cultivars set pollen in abundance Others typically set very few catkins. Some cultivars drop their catkins prior to pollen shed. Since one good Daviana catkin is estimated to produce 4 million pollen grains, the amount of pollen produced by a single pollinizer tree is tremendous.

The hazelnut tree is a wonder

Jeff Olson, Extension agent, Oregon State University

HGA newsletter, Autumn 2003

Horticulturally speaking, the hazelnut tree is clearly out of the ordinary. It is more than just nutty. It is unique and wonderful. The way in which it achieves pollination in the winter and completion of nut set in the spring, is like no other horticultural crop that I have ever heard of. It is a “one of a kind”, just like some of the people in our industry!

Over the years, many researchers have investigated the growth and development of the hazelnut, in an attempt to unlock some of the secrets of this unusual plant. In fairly recent times, 1979, Dr. Maxine Thompson, of OSU, published a very informative article about the growth and development of the hazelnut flowers and nuts. It is one of those information-packed articles that is peppered with words like: megasporocytes, achesporial cells, funiculus of the anatropous ovule…you know what I mean, light reading.