VigorClone® Field Trials
The VigorClone® pistachio rootstock from Duarte Nursery is a high vigor clone that leads the market in crop production. After 20 years of field testing, it is now available to growers in California for spring planting.
In 2002, Duarte Nursery collaborated with farmers in Coalinga, California to plant a field trial on clonal pistachio rootstocks. 14 new clonal rootstocks were observed in identical conditions alongside Duarte Nursery’s then-standard UCB-1 pistachio clone. In the 20 years since then, two clones from that trial have stood out as exceptional rootstocks: the V211 and the V214. These clonal selections have now been patented as the VigorClone® pistachio.
The VigorClone® stands out not only for its significantly increased trunk size, but also for having over twice the average crop yield of the UCB-1 clone. In this trial, all clonal rootstocks received the same inputs, meaning the VigorClone® produced double the amount of nuts without increasing water use.
Increased Crop Yield
Over eight years of data collection, the VigorClone® selections V211 and V214 averaged over double the crop yield of the standard UCB-1 pistachio clone. The trees in this orchard were spaced at 135 trees per acre.
The VigorClone® selection V211 averaged 3,889 pounds of pistachios per acre every year, and V214 averaged 4,069 pounds per acre. Both of these were over double the UCB-1’s average crop yield of 1,913 pounds per acre.
Larger Trunk Size
The trunk sizes of the VigorClone® selections set them apart from the standard UCB-1 in terms of vigor. V211 and V214 have steadily increased their lead on the UCB-1 since 2014.
Vigor is the rate of growth for pistachio trees, and is often considered to have benefits and drawbacks for seedling pistachio trees. Seedling pistachios have variable genetics, and while a particularly vigorous tree can grow larger, it is also likely to outcompete nearby trees for resources and stunt their growth as a result.
The VigorClone® doesn’t face this risk. As a clonal rootstock, the genetics of every tree are identical, so each one has the same vigor. Because clonal trees grow far more uniformly, individual trees don’t hoard resources from their neighbors.
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The importance of vigor in pistachio rootstocks shows when trunk circumference is compared directly with yield over eight years. Both of the VigorClone® selections have routinely outperformed the UCB-1 clone in both categories over eight years.
Pistachio orchards routinely cycle through high and low crop years. The VigorClone® selections not only produce significantly more than the UCB-1 during high crop years, they also keep their lead in low crop years. This lets growers keep benefiting from their improved yields every year.
The crop yield is at the bottom of the graph in bars, and the trunk circumference is at the top. In 2015, no data was taken because of statewide water scarcity.