2024-09-26 PL-INT-2024-008813 GP 2045 Draft Comments - A. Longo

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level of CO2 enrichment impacts fruit quality and careful consideration is needed to ensure an appropriate balance between levels of e[CO2]and final yield.Lycopene is an important phytonutrient,is sold commercially as a dietary supplement,and has been reported to possess anti-cancer properties and can improve cardiovascular health[26,27]. I-carotene is the precursor for Vitamin A,also known as retinol.Vitamin A is an essential micronutrient playing important roles in growth and development,vision[281 and the immune system[29].More than a third of all pre-school children and a significant number of pregnant women around the world are affected by Vitamin A deficiency,increasing the risk of night blindness and miscarriage[3o,31].Importantly,most people suffering from a deficiency in Vitamin A show no clinical symptoms resulting in a phenomenon termed"Hidden Hunger"[32].Production of crops with increased Vitamin A is therefore an important target for improving the diet and health of these at-risk groups;enhanced uptake of carbon may be a useful approach to achieve this.Increases in the Vitamin A precursor(3-carotene has been observed in tomato fruit grown under e[CO2]of 800- 900 ppm,in addition to a 28°7°increase in vitamin C at ripe stage and an-8%increase in total soluble solids(Table 1).Zhang et al.[13],suggested that under these growth conditions,improved vitamin A and C and increased carotenoid content may be attainable. Carotenoids are also the precursors of several flavour and aroma compounds.I-carotene is cleaved by carotenoid cleavage dioxygenases CCDM and CCD4[26,33-35],to form the aromatic apocarotenoid 0-ionone,which is important to tomato fruit flavour.Furthermore,lycopene,shown to increase under e[CO2]is cleaved by CCD1 to form several important flavour and aroma compounds including 6,10-dimethyl-3,5,9-undecatrien-2- one(pseudoionone[34];,6-methyl-5-hepten-2-one(MHO[36];and geranial[37].MHO has been shown to be an important contributor to tomato fruit flavour[38,39]and has also been shown to accumulate in tomato fruit with higher lycopene levels[40].It is therefore apparent that growth in e[CO2]can increase a range of key flavour and nutraceutical precursor compounds present in tomato fruit;this phenomenon deserves further study, the optimal levels of[CO2]are currently not clear and more work is needed to better understand the relationship between CO2,assimilation carotenoid content,flavour and overall quality(Table 2). Similar results have also been found in pepper crops,with yield increase of 12.9%—370.2%reported when grown at e[C07]of between 450 ppm— l000 ppm(Table 2)with most other studies reporting yield increases in the range of 12.9%—47.4%in the absence of other parameters[41-47]. However,it should be noted that growth at-800 ppm e[CO2]was found to reduce sweet pepper total amino acid content by up to 29%,including reductions in the sweet tasting amino acids alanine and glycine,which could be detrimental to the perceived fruit flavour[42].Yield was also found to vary with different irrigation programmes[41,48],nitrogen sources[48],substrate salinity[42,44]and pruning regimens[46].Given that previous work in tomato has shown an increase in potential phytonutrients in fruit grown at 55o ppm and a decrease in those grown at 700 ppm, further research is needed to better identify the specific quantity of CO2 fertilisation necessary for maximally improved yield in solanaceous crops, especially when considering that CO2 uplift is often accompanied by additional treatments,such as increased nutrient and nitrogen fertilisation (Figure 2). Impact of elevated atmospheric[CO2]on yield and nutritional quality of tomato Table 1 Impact of elevated atmospheric[CO2]on yield and nutritional quality of tomato CO2Treatment AdditionalTreatment(s) Fruit Yield Fruit Quality Ref 510 ppm N/A 9.9%increase in fruit yield. N/A [45] 590 ppm root drying Fruit dry weight not significantly affected by[CO2] N/A [15 across all irrigation treatments. 5] 375 ppm- Ozone treatment 24%increase in fruit yield.31%decrease in fruit yield N/A [15 675 ppm 80 nmol mol when exposed to ozone.Ozone and CO2 treated fruit 6] yields were not significantly different to plants grown in ambient conditions. 550 ppm N/A 54%increase in fruit yield at 550 ppm and 125% 1.4%-11.4%decrease in total soluble solids,27.3%- [19] 700 ppm increase in fruit yield at 700 ppm. 31.8%decrease in total acids and 16.1%-29.0% increase in vitamin C. +2°C increase in 18.4%-21.4%increase in fruit yield due to increased 10%increase in total sugars,44%increase in vitamin C, [25] temperature [CO2]. 32%increase in lycopene at e[CO2]in absence of other treatments.e[CO2]rescues reduction in quality from increased temperature. 650 ppm N/A 17%increase in fruit yield at 650 ppm and 48% N/A [3] 1000 ppm increase in fruit yield at 1000 ppm. 700 ppm Doubled N fertilisation N/A 13%-25%decrease in fruit lycopene content across [15 harvests with e[CO2].9%increase in fruit lycopene 7] content with increased N fertilisation. UV-B exposure up to 38%increase in fruit yield in absence of additional UV- Up to-22%increase in soluble sugars,-24%increase in [15] 1.744 kJ m-2 B treatment,up to 46%increase in fruit yield with UV-B organic acids,-40 increase in vitamin C and-47% treatment. increase in lycopene content of fruits grown under e[CO2]and UV-B treatment. PDF 700 ppm N/A -30%increase in individual fruit weight. -18%increase in vitamin C.-Up to 20%reduction in [:6] H el rsly, 900 ppm major acids(citric,malic,oxalic).-45%increase in Oxford University Press uses cookies to enhance your experience on our website.By selecting`accept all'you are agreeing to our use of cookies.You can change your cookie setting More information can be found in our Cookie Policy.