Building a Better Christmas Tree

Most can agree that a good Christmas tree is one that “sheds” very little. North Carolina State University researchers are studying Fraser fir Christmas trees to improve qualities such as needle retention, which is their ability to hold onto their needles after they’ve been cut, as well as their overall smell and shape.

摘要spoke to贾斯汀whitehil顾问公司, assistant professor of forestry and environmental resources at NC State and director of the Christmas Tree Genetics Program, about everything we ever wanted to know about Christmas trees – from how long they last, to the science that scientists are doing to improve them using genetics.

摘要：How long do Christmas trees keep?

Whitehill: Generally, trees will “keep” through the holiday season to mid-January if they are watered and cared for properly, but it also depends on the species and the tree’s genetics. One of the reasons that the Fraser fir makes such a great Christmas tree, and why it’s called the perfect Christmas tree, is it has a very good ability to hold onto its needles after it’s been harvested.

TA：您是否正在努力改善Fraser Fir中的针头保留？

Whitehill: Needle retention is a trait that is very strongly controlled by the genetics of the tree. Through the research efforts of the NC State Christmas tree genetics program, we’ve identified trees that are really good at holding onto their needles after harvest. Those trees were planted into a seed orchard and we are working to get those genetically improved seeds to growers, hopefully by 2028.

The NC State Christmas tree genetics program is more than 40 years old. So, my program is built on the work of those that came before me. Our genetically improved trees started out as seeds that were collected from natural wild stands across the range of Fraser fir trees in North Carolina. In total, the NC State Christmas tree genetics program identified 25 elite trees from an initial set of 30,000 to 40,000 trees. These elite 25 trees were selected after they had been evaluated for traits like needle retention, growth and form. Those elite trees form the basis of our genetic improvement program.

我们正在研究弗雷泽冷杉树，因此在收获后树木的生命周期中，只有不到1％的针头会掉落。将其与其他物种，甚至尚未得到遗传改善的Fraser Fir进行比较，在整个假期中，您可能会损失多达30％的针头。

TA: Which Christmas trees are best for people with allergies?

Whitehill: The aroma of a Fraser fir Christmas tree is what a lot of people associate with Christmas. However, some people are sensitive to that intense aroma. I’m exploring that question with a consumer aroma scientist now to see if we can identify how people interact with these trees. For instance, what are the chemicals that consumers like and give a Christmas tree its characteristic aroma?

如果您患有过敏，并且发现真正的树木因那些香气化学物质而困扰您，那么您可能会做得很好，有些种植者认为像Leyland Cypress这样的非过敏剂。Leyland柏树制成非常漂亮的圣诞树，往往没有香气，因此每个人都有一些东西。

对于我们的计划，我们还需要考虑这些化合物和香气如何影响圣诞树农场（如鹿）的害虫，鹿往往会被某些树木吸引而不是由于这些独特的化学物质而被吸引而不是其他树木。例如，我们认为有一种化合物特别是在田野中对鹿的威慑作用，并且在某些不太受鹿偏爱的圣诞树物种中发现。该化合物是与柠檬相关的新鲜香气负责的化学物质。该化合物由树的遗传学控制。由于这些独特的香气，我们需要平衡在田间做得更好的树木与将享受香气作为圣诞树的人们的喜好。

TA:What else are you working on?

Whitehill: The big one on the horizon is the cascading impact of climate change. I think we need to be prepared for what’s to come. This isn’t specific to Christmas trees alone, but all forest trees and crop plants around the world. We need trees that are going to be able to withstand or be resilient in those new future environments and climates. The other trait we are looking at is pest resilience. As climate changes, temperatures increase, the dynamics of pests and pathogens will change as well. We need to help our growers so they can continue to be successful.

TA：气候变化正在改变弗雷泽冷杉农场吗？

Whitehill: It seems that maybe the winters aren’t as cold as they used to be. Because of that, we’re concerned about the possibility that pathogens and pest populations are starting to build up. Once populations of these pests increase, you start to see an increase in problems. This is something on the horizon we’re keeping our eye on.

TA：北卡罗来纳州在圣诞树生产中第二位是俄勒冈州吗？

Whitehill：俄勒冈州以圣诞树的形式提供的东西与北卡罗来纳州所提供的不同。我认为，北卡罗来纳州拥有圣诞树的主要物种。弗雷泽冷杉是一个非常独特的物种。由于上一个冰河时代的冰川后退，该物种被隔离到高山生态系统中。因此，弗雷泽冷杉只有在阿巴拉契亚山脉沿着高海拔高度（高于5,000英尺）的高海拔地区发现。在这些地区，大约有六到九个小口袋。它们存在于这个非常小的生态位。我们很幸运能拥有该物种，这就是北卡罗来纳州拥有主要的圣诞树的原因，因为我们州独有的独特物种。