PS 33-142 - Through the grapevine: exploring intraspecific functional trait variation in grape varieties

Background/Question/Methods

Functional trait variation in plants of the same species or genotype, is a critical determinant of ecosystem processes. This is especially true in agroecosystems, where variability in traits forming the Leaf Economics Spectrum (LES) among and within crops, play a key role in governing agroecosystem processes including yield, water-use efficiency, and nutrient cycling. However, studies evaluating the extent, causes, and consequences of within-species variation in LES traits for some of the world’s most common crops remains limited. We assess intraspecific variation in LES traits in wine grapes (Vitis vinifera), one of the world’s most commercially important crops. We specifically assessed variation in 12 physiological, morphological, and chemical traits measured on 90 leaves, derived from in six varieties, across two times in the growing season. We then use this dataset to: 1) quantify if or how varieties differ from one another across an intraspecific LES; and 2) evaluate the relative contributions of genetic vs. phenotypic variation to LES traits in grape.

Results/Conclusions

Grape traits covary along an intraspecific LES, similar to wild plants. Across varieties, high rates of mass-based photosynthesis (Amass), and nitrogen (N), are coupled with low mass per area (LMA), while the opposite traits define the “resource conserving end” of grape LES. Variety was the most important predictor of physiology (Amass) and morphology (area/mass; 27.0-37.8% of variance explained). Chemical traits and LMA were best explained by time of year (47.3-77.4% of variance explained), with all varieties expressing greater resource conservation (i.e., higher LMA, lower leaf N, lower Amass) later in the season. White varieties expressed more resource acquiring LES trait syndromes vs. reds; differences largely related to white varieties expressing higher Amass. Traits related to leaf hydraulics including stomatal conductance and water-use efficiency were better explained by spatial location (10.9-12.8% of variance explained), indicating these traits are regulated by local environmental conditions. Our findings uncover a deeper understanding of intraspecific variation in LES and related leaf traits within one of the world’s most important crops, highlight the contributions of genetic vs. phenotypic factors in structuring this variation, and point to the role of domestication in governing trait relationships in agriculture.