Potato tuber yield, quality, mineral nutrient concentration, soil health and soil food web in conventional and organic potato systems

Field grown tubers from two conventional and two organic potato farms were compared to determine genotypic and environmental effects on tuber yield, quality, and tuber mineral content. Rhizosphere and bulk soil from the same conventional and organic farms were compared to determine genotypic and environmental effects on soil bacteria, fungi, protozoa, nematodes and soil health.;Analyses of variance revealed a significant effect of the interaction between genotype and location on total tuber yield as well as the <4oz, ≥4oz, and ≥10oz tuber weight ranges (p<0.05). Total yields were grouped the tightest with CO00291-5R, and showed the greatest variability in 'Fortress Russet'. In the greater than or equal to 10oz tuber weight range CO97087-2RU, 'Fortress Russet,' and'Sangre-S10' each exhibited much greater yields at one of the conventional locations with 'Fortress Russet' showing the greatest variability across locations. Tubers from conventionally managed locations had significantly greater total yield, ≥4oz tubers, ≥6oz tubers, and ≥10oz tubers. There were also significant effects of location within management for all weight ranges, significant effects of genotype for all weight ranges, and significant interaction effects for all weight ranges except ≥6oz tubers.;There was a significant effect ofthe interaction of genotype and location on specific gravity (p<0.05). CO00291-5R and 'Sangre-S10' had low variability across locations, while CO97087-2RU had the greatest variability across locations. There was a significant effect of location on specific gravity (p<0.05) with location one of the organic locations having the highest specific gravity at 1.086 and the two conventional locations having the lowest values at 1.079 and 1.080, respectively. There was a significant effect of genotype on specific gravity.;'Fortress Russet' was the only clone in which location hada significant impact on the prevalence of hollow heart (chi-square=9.881 df=3, p=0.0196) with a maximum of 10.7% of total yield exhibiting hollow heart. 'Fortress Russet' was also significantly impacted by location with regard to growth cracks (chi-square=8.309, df=3, p=0.0400) with a maximum of 5.6% of total yield as was Sangre-S10 (chi-square=12.500, df=3, p=0.0059) with a maximum of 6.1% of total yield. No clones were significantly impacted by location with regard to brown center, knobs, or misshapes.;The interactionbetween genotype and location had a significant effect on tuber potassium concentration (p=0.0127), but not tuber iron or zinc (p=0.3526 and p=0.5259, respectively). CO97087-2RU exhibited much higher levels of tuber potassium at one of the conventional locations than the other locations. 'Fortress Russet' and 'Sangre-S10' exhibited a larger range of tuber potassium concentrations across all four locations compared to the remaining clones. Tuber mineral iron and zinc concentrations were significantly different between tubers from conventionally versus organically managed fields (p<0.05). Tubers from conventionally managed fields had on average 1.91 % dry weight K, 122.8 mg/kg Fe, and 17.4 mg/kg Zn. Tubers from organically managed fields had on average 1.91 % dry weight K, 100.1 mg/kg Fe, and 14.0 mg/kg Zn. There was a significant main effect of location on tuber mineral potassium, iron, and zinc concentrations. There was a significant main effect of genotype on tuber mineral potassium, iron, and zinc concentrations.;There was a significantinteraction effect between genotype and location for soil bacteria and fungi biomass (p<0.05). 'Sangre-S10' showed little variation in soil bacteria between locations, whereas CO97087-2RU and 'Fortress Russet' did. CO97087-2RU showed much greater differences in soil fungi between conventional and organic locations, as did 'Fortress Russet' and 'Sangre-S10'. There was a significant difference in soil fungi, amoebae, and ciliate biomass between management regimes (p<0.0001 for each). Organically managed soils averaged 254 microg fungi /g soil, while conventionally managed soils averaged 142 microg fungi /g soil. Organically managed soils averaged 236,265 amoebae/g soil, while conventionally managed soils averaged 50,872 amoebae/g soil. Organically managed soils averaged 525 ciliates/g soil, while conventionally managed soils averaged 32 ciliates/g soil. There is a significant effect of location on all soil food web constituents except for flagellates (p<0.05). There was a significant effect of clone on soil fungi and ciliates (p<0.05).;There were significant differences in soil respiration, organic carbon, and organic nitrogen between management (p<0.05). Soil from organically managed locations had mean soil respiration of 22.1 ppm CO2/24hrs compared to conventionally managed locations with 16.9 ppm CO2/24hrs. Soil from organically managed locations had mean soil organic carbon pools of 140 ppm compared to conventionally managed locations with a mean of 97 ppm. Soil from organically managed locations had mean soil organic nitrogen pools of 31.8 ppm compared to conventionally managed locations with a mean of 24.4 ppm. There was a significant main effect of location on soil respiration, organic carbon, and organic nitrogen (p<0.05).;The purposes of thisstudy were to identify breeding material that may be used to improve yield and mineral nutrient concentrations of potatoes in conventional and organic systems. There were no clones that performed better in organic systems than conventional, but CO00291-5R did have the least variability in tuber yield across locations. CO00291-2RU was identified as a good candidate for improving potato potassium and zinc concentrations; CO97087-2RU as a good candidate for improving potato iron and potassium concentrations; and Sangre-S10 as a good candidate for improving potato iron concentration. While yield was reduced under organic management, tuber specific gravity was increased compared to conventional management. Organic management also improved soil food web structure and soil health by increasing soil fungal, amoebae, and ciliate biomass, microbial activity, and carbon and nitrogen concentrations.