Abstract
At an organic farm in California, managed biodiversity was manipulated by establishing a mustard cover crop (MCC) and fallow during winter, and after incorporation, tomato mixtures of one, three, and five cultivars were planted in the spring (1-cv, 3-cv, and 5-cv, respectively). It was hypothesized that cultivar mixtures may increase yields over a monoculture if disease pressure or nitrogen (N) availability is affected by the previous cover crop. The monoculture (1-cv) of the grower’s preferred cultivar was compared with mixtures of it and other high-yielding cultivars in the region. Soil nitrogen, soil microbial biomass carbon (MBC), soil emissions of carbon dioxide (CO 2 ) and nitrous oxide (N 2 O), crop nutrient uptake, biomass, fruit quality, intercepted photosynthetically active radiation (PAR), and disease symptoms were measured. The MCC reduced soil N leaching potential during winter and immobilized soil N early in the tomato season as suggested by higher soil MBC and CO 2 emissions. Tomatoes had higher PAR, aboveground biomass, fruit yields, and harvest index in the winter fallow than in the winter MCC, likely due to higher N availability in the fallow plots after transplanting. All cultivar mixtures had fairly similar yield and shoot biomass within fallow and MCC, probably explained by the low genetic diversity among California modern tomato cultivars. However, at mid-season (75 days after planting (DAP)), the 3-cv mixture had higher shoot and fruit biomass, by 46% and 63%, than the monoculture in the MCC, indicating some plasticity under lower N availability. In the fallow treatment, soil CO 2 emissions were lower in the 3-cv mixture than the monoculture at 77 and 100 DAP. Tomatoes in the 3-cv mixture were redder than the monoculture. The 3-cv mixture thus had some minor advantages compared with the monoculture, but overall, there was little evidence of higher ecosystem functions from mixtures vs. monoculture. Further research on mixtures of processing tomatoes may only be warranted for conditions of higher environmental stress than occur in California organic farms or if specific genotypic traits become available such as for disease resistance or improved nutrient uptake.
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Claims 10
Claim · model-written summary
The mustard cover crop reduced soil N leaching potential during winter compared with fallow.
Verbatim
t0“processing tomato”
e1“The MCC reduced soil N leaching potential during winter”
e2“establishing a mustard cover crop (MCC) and fallow during winter”
Claim · model-written summary
The mustard cover crop immobilized soil N early in the tomato season, as suggested by higher soil MBC and CO2 emissions.
Verbatim
t0“processing tomato”
e3“immobilized soil N early in the tomato season as suggested by higher soil MBC and CO 2 emissions”
Claim · model-written summary
Tomatoes in the winter fallow had higher PAR, aboveground biomass and fruit yields than in the winter MCC.
Verbatim
t0“processing tomato”
e4“Tomatoes had higher PAR, aboveground biomass, fruit yields, and harvest index in the winter fallow than in the winter MCC”
e5“likely due to higher N availability in the fallow plots after transplanting”
Claim · model-written summary
Tomatoes in the winter fallow had a higher harvest index than in the winter MCC.
Verbatim
t0“processing tomato”
e4“Tomatoes had higher PAR, aboveground biomass, fruit yields, and harvest index in the winter fallow than in the winter MCC”
Claim · model-written summary
Cultivar mixtures had fairly similar yield and shoot biomass to the monoculture within fallow and MCC treatments.
Verbatim
t0“processing tomato”
e6“All cultivar mixtures had fairly similar yield and shoot biomass within fallow and MCC”
e7“The monoculture (1-cv)”
Claim · model-written summary
At mid-season, the 3-cv mixture had higher shoot and fruit biomass, by 46% and 63%, than the monoculture in the MCC.
Verbatim
t0“processing tomato”
e1“at mid-season (75 days after planting (DAP)), the 3-cv mixture had higher shoot and fruit biomass, by 46% and 63%, than the monoculture in the MCC”
Claim · model-written summary
In the fallow treatment, soil CO2 emissions were lower in the 3-cv mixture than in the monoculture at 77 and 100 DAP.
Verbatim
t0“processing tomato”
e1“In the fallow treatment, soil CO 2 emissions were lower in the 3-cv mixture than the monoculture at 77 and 100 DAP”
Claim · model-written summary
Tomatoes in the 3-cv mixture were redder than in the monoculture.
Not reportedDirection
Verbatim
t0“processing tomato”
e1“Tomatoes in the 3-cv mixture were redder than the monoculture”
Claim · model-written summary
There was little evidence of higher ecosystem functions from mixtures than from monoculture.
Verbatim
t0“processing tomato”
e1“there was little evidence of higher ecosystem functions from mixtures vs. monoculture”
Claim · model-written summary
Further research on mixtures of processing tomatoes may be warranted only under higher environmental stress than California organic farms, or if specific genotypic traits become available.
Verbatim
t0“processing tomato”
e1“Further research on mixtures of processing tomatoes may only be warranted for conditions of higher environmental stress than occur in California organic farms”
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Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.