No abstract

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.   ********* In press - Online First. Article has been peer reviewed, accepted for publication and published online without pagination. It will receive pagination when the issue will be ready for publishing as a complete number (Volume 47, Issue 4, 2019). The article is searchable and citable by Digital Object Identifier (DOI). DOI link will become active after the article will be included in the complete issue. *********

Black locust currently is considered to be the most important tree species of short-rotation forests in Hungary with the purpose of either woody biomass or industrial wood. Despite the general supposition on the drought tolerance of the species, water availability seems to be a more limiting factor to exploit the growing potential of highly productive new varieties than nutrient amendments. Preliminary measurements of the current study were made on the connection between the depth of the water-retaining soil layer and the growth of saplings on black locust plantations. A significant negative correlation was found between the depth of the water-retaining layer, the stem diameter and the height of the saplings. To investigate the phenomenon, a model experiment was launched with loamy sand soil in the pots. During six weeks, pots were watered every morning up to the weight referring to the 30, 40, 60 and 80% of field capacity (FC). Our results showed that 30% FC was only sufficient for the survival of the saplings, growth was only noticeable at plants with 40% FC or more. During the first 4 weeks, differences in growth and cumulative evapotranspiration between the 60% and 80% FC treatment were not considerable. However, in the last two weeks, saplings with the highest FC produced substantially higher biomass, resulting in a one-third higher final weight than those of FC 60%. Even with the limited soil capacity of the pots, water use of these saplings of 1 m height and 1 cm stem diameter exceeded 1.5 L per day. Our results confirmed that black locust is a water-intensive species with a high water use potential, which emphasizes the importance of irrigation on nurseries and the first years of plantations.