The impact of environmental changes on the yield and nutritional quality of fruits, nuts and seeds: a systematic review

Abstract

Background: Environmental changes are predicted to threaten human health, agricultural production and food security. Whilst their impact has been evaluated for major cereals, legumes and vegetables, no systematic evidence synthesis has been performed to date evaluating impact of environmental change on fruits, nuts and seeds (FN&S) - valuable sources of nutrients and pivotal in reducing risks of non-communicable disease.

Methods: We systematically searched seven databases, identifying available published literature (1970-2018) evaluating impacts of water availability and salinity, temperature, carbon dioxide (CO2) and ozone (O3) on yields and nutritional quality of FN&S. Dose-response relationships were assessed and, where possible, mean yield changes relative to baseline conditions were calculated.

Results: 81 papers on fruits and 24 papers on nuts and seeds were identified, detailing 582 and 167 experiments respectively. A 50% reduction in water availability and a 3-4dS/m increase in water salinity resulted in significant fruit yield reductions (mean yield changes: -20.7% [95%CI -43.1% to -1.7%]; and -28.2% [95%CI -53.0% to -3.4%] respectively). A 75-100% increase in CO2 concentrations resulted in positive yield impacts (+37.8%; [95%CI 4.1% to 71.5%]; and 10.1%; [95%CI -30.0% to 50.3%] for fruits and nuts respectively). Evidence on yield impacts of increased O3 concentrations and elevated temperatures (>25°C) was scarce, but consistently negative. The positive effect of elevated CO2 levels appeared to attenuate with simultaneous exposure to elevated temperatures. Data on impacts of environmental change on nutritional quality of FN&S were sparse, with mixed results.

Discussion: In the absence of adaptation strategies, predicted environmental changes will reduce yields of FN&S. With global intake already well-below WHO recommendations, declining FN&S yields may adversely affect population health. Adaptation strategies and careful agricultural and food system planning will be essential to optimise crop productivity in the context of future environmental changes, thereby supporting and safeguarding sustainable and resilient food systems.

Keywords: Environmental change; Environmental exposure; Fruits; Nuts; Seeds; Yields.

Figure 1.

PRISMA chart showing the numbers of papers at each stage of the screening process. (A). Fruits; (B). Nuts and seeds. *Covering the combined search for systematic reviews on (1) vegetables and legumes—published elsewhere (10) and (2) fruits. **Two papers analysed both fruits and vegetables/legumes.

Figure 2.

Geographical spread of experiments on fruits, nuts and seeds reported in papers identified for this systematic review.

Figure 3.

(A) Change in fruit yield in response reduced water availability—by crop group and (B) Change in fruit yield in response increased water salinity—by crop group.

Figure 4.

Change in five quality parameters of fruit groups in response to reduced water availability

Figure 5.

Change in yields of nuts in response to change of water availability—by crop group.

Figure 6.

Change in yields of peanuts in response to change of temperature, salinity levels and CO₂ concentrations—by crop group.