Perennial vegetables: A neglected resource for biodiversity, carbon sequestration, and nutrition

collard greens (Brassica oleracea Acephala group), pak choi and Chinese cabbage (Brassica rapa), pepper (Capsicum annuum), cucumber (Cucumis sativus), summer squash and zucchini (Cucurbita spp.), winter squash (Cucurbita spp.), globe artichoke (Cynara scolymus), lettuce (Lactuca sativa), avocado (Persea americana), green bean (Phaseolus vulgaris), pea (Pisum sati- vum), tomato (Solanum lycopersicum), eggplant (Solanum melongena), spinach (Spinacea oler- acea), and sweet corn (Zea mays). While cassava leaf (Manihot esculenta) is also tracked by FAO, we opted to exclude it as an outlier due to its exceptionally high values. The values for summer squash/zucchini and winter squash represent the mean values for Cucurbita moschata, C. pepo, C. maxima, and unspecified Cucurbita spp, at the unripe stage for summer squash/zucchini and ripe stage for winter squash. We constructed categorical levels for each nutrient based on nutrient levels across the set of the reference crops (Table 2). For each nutrient, we divided the range found within the refer- ence set into “low” (the lowest third), “medium” (the middle third) and “high” (the highest third). We classified nutrient concentrations below the lowest value found in the reference veg- etables as “very low,” while those above the highest value as “very high.” We classified nutrient values more than twice the highest reference crop levels “extremely high.” For Vitamin A, the lowest point in the range for the reference vegetables was 0. For this reason the “very low” cate- gory is not applied to Vitamin A.

For those nutrients for which data was acquired, we compared nutrient content across cate- gories of crop form and part used, in terms of the percentage of crops in each category with one or more superabundant nutrients. Data was not available for every nutrient for all refer- ence crops. Similarly, data was not available for every nutrient for each PV (see S1 Fig in the supplementary materials for information on the number of data points for each nutrient, plant form, and part used). It is possible that complete data for reference crops and/or PVs would shift our results slightly. In order to assess the potential of PV crops to ameliorate nutritional deficiencies associated with traditional malnutrition (iron, zinc, vitamin A, iodine, and folate) and industrial malnu- trition (including fiber, calcium, magnesium, and antioxidants), we scored each crop sepa- rately based on the abundance of nutrients relevant to each syndrome. In both cases, “extremely high” levels were given 3 points, “very high” two points, and “high” one point. A combined score of 6 was set to qualify species as “multi-nutrient” crops. In order to relate nutrient content with agroecological niche, we also show superabundant and multi-nutrient PVs according to the plant form and part used. Table 2. Nutrient concentration classes based on reference crop nutrient levels. Fiber Ca Fe Mg Zn A B9 C E % mg/100g mg/100g mg/100g mg/100g Mg RAE mcg/100g mg/100g mg/100g Very low 0.00–0.39 0.00–11.84 0.00–0.46 0.00–11.24 0.00–0.15 0.00 0.00–13.49 0.00–5.64 0.00–0.04

Low 0.40–1.45 11.85–86.71 0.47–1.01 11.25–35.75 0.16–0.29 0.00–0.18 13.50–73.07 5.65–42.33 0.05–0.73 Medium 1.46–2.50 86.72–161.57 1.02–1.55 35.76–60.26 0.30–0.42 0.19–0.37 73.08–132.63 42.34–79.01 0.74–1.42 High 2.51–3.85 161.58–238.70 1.56–2.11 60.27–85.50 0.43–0.56 0.38–0.55 132.64–194.00 79.02–116.80 1.43–2.54 Very high 3.59–7.15 238.71–477.40 2.12–4.21 85.51–171.00 0.57–1.12 0.56–1.11 194.01–388.00 116.81–233.59 2.55–5.08 Extremely high 7.16+ 477.41+ 4.22+ 171.01+ 1.13+ 1.12+ 388.01+ 233.6+ 5.09 “Very low” indicates nutrient values lower than the lowest value for the reference vegetables. “Low” is from the lowest tertile of the reference vegetable range, “medium” is the middle tertile, and “high” is the highest tertile. “Very high” ranges from the highest end of the range to twice the highest end, while “extremely high” is more than double the highest end of the range. https://doi.org/10.1371/journal.pone.0234611.t002 PLOS ONE Perennial vegetables: A neglected resource for biodiversity, carbon sequestration, and nutrition PLOS ONE | https://doi.org/10.1371/journal.pone.0234611 July 10, 2020 7 / 19