The range of nutrients that were quantified in almonds from trees exposed to a single resource or pollination treatment.

¶<p>Oleic acid is included in the total monounsaturated fatty acids; linoleic and linolenic acid are included in the total polyunsaturated fatty acids.</p

The nutritional composition of almonds from trees that received different resource treatments alone and in combination.

<p>Treatments: no fertilizer (NF), reduced water (RW), self-pollination (SP) and cross-pollination (CP). Single and combined treatments are separated by a dashed line. The boxes show the median, 25^th and 75^th percentiles and the letters a,b,c,d, indicate significant differences from Tukey’s HSD test at <i>P</i><0.05.</p

Pollination and Plant Resources Change the Nutritional Quality of Almonds for Human Health

<div><p>Insect-pollinated crops provide important nutrients for human health. Pollination, water and nutrients available to crops can influence yield, but it is not known if the nutritional value of the crop is also influenced. Almonds are an important source of critical nutrients for human health such as unsaturated fat and vitamin E. We manipulated the pollination of almond trees and the resources available to the trees, to investigate the impact on the nutritional composition of the crop. The pollination treatments were: (a) exclusion of pollinators to initiate self-pollination and (b) hand cross-pollination; the plant resource treatments were: (c) reduced water and (d) no fertilizer. In an orchard in northern California, trees were exposed to a single treatment or a combination of two (one pollination and one resource). Both the fat and vitamin E composition of the nuts were highly influenced by pollination. Lower proportions of oleic to linoleic acid, which are less desirable from both a health and commercial perspective, were produced by the self-pollinated trees. However, higher levels of vitamin E were found in the self-pollinated nuts. In some cases, combined changes in pollination and plant resources sharpened the pollination effects, even when plant resources were not influencing the nutrients as an individual treatment. This study highlights the importance of insects as providers of cross-pollination for fruit quality that can affect human health, and, for the first time, shows that other environmental factors can sharpen the effect of pollination. This contributes to an emerging field of research investigating the complexity of interactions of ecosystem services affecting the nutritional value and commercial quality of crops.</p></div

Non-metric multi-dimensional scaling (NMDS) of the nutritional composition of almonds.

<p>Almonds were collected from trees that had received one of four treatments: reduced water (RW), no fertilizer (NF), cross-pollination (CP) and self-pollination (SP). The content of a wide range of nutrients (listed in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0090082#pone-0090082-t002" target="_blank">Table 2</a>) was quantified in the laboratory (methods detailed in the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0090082#pone.0090082.s001" target="_blank">supporting information S1</a>). Permutational multivariate analysis of variance using Bray-Curtis distances was performed on the nutritional content of the almonds, with the treatment as the grouping factor, replicated at the tree level. Each point on the graph represents an individual tree that was exposed to one of the treatments and the hulls link trees exposed to the same treatment. The further apart the points are on the graph, the more different the nuts’ nutritional composition.</p

The different treatments whole almond trees received (5 trees each, for details see methods).

<p>The different treatments whole almond trees received (5 trees each, for details see methods).</p