Effects of Mycorrhiza Inoculation and Grafting for Sweet Pepper (Capsicum annuum L.) Crop Under Low-Tech Greenhouse Conditions

In low-cost, unheated greenhouses and tunnels the use of arbuscular mycorrhizal fungi (AMF) and/or grafting can be a less expensive and sustainable solution to combat the adverse effects of monoculture, instead of costly soilless culture. The aim of the present study was to investigate the effects of a commercially available AMF inoculant and grafting on sweet pepper, under circumstances of modelling commercial low-tech greenhouse production. ‘SV9702PP F1’ sweet pepper hybrid was cultivated for seven months in an unheated greenhouse. Beside the control, three treatments were applied: ungrafted AMF treated plants, plants grafted on ‘Bagi F1’ hybrid and AMF treated plus grafted plants. AMF was applied into the planting holes just before transplanting. AMF treatment had positive effects on relative chlorophyll content of leaves (expressed in SPAD value), on plant stand, on plant mass production, on yield and on root colonization rate, despite the high presence of indigenous populations of AMF in the greenhouse soil. With the applied rootstock/scion combination, grafting did not significantly affect the aforementioned parameters. SPAD values were increased by the AMF treatment during periods when smaller doses of nitrogen (less than 0.8 g N per m-2 week-1) were applied. Significant positive correlation was found between root colonization rate and marketable yield. AMF treatment increased the yield by 18% (from 12.43 to 14.74 kg m-2), mostly due to higher number of fruits. Yield increase was mainly realised during the last third of the harvest period, when the applied nutrient doses were low and temperature conditions were suboptimal.