Browsing by Subject "jakojuuri"

Plants absorb water best from fertigation solution with low nutrient concentration. Yet, in intensive greenhouse production high nutrient concentrations are used in fertigation to avoid nutrient deficiencies and decrease in yields. In split-root cultivation the root system of a plant is separated into two growing medium compartments, in which case the other half receives fertigation solution with high EC (electrical conductivity) and the other with low EC. Especially greenhouse cucumber, susceptible to water supply problems caused by salinity of growing medium, is found to benefit from this technique in increased yields. The objective of this study of split-root cultivation of greenhouse cucumber conducted in MTT Agrifood Research Finland was to improve the technique especially in respect of EC of fertigation solutions. In addition to single-root and traditional split-root cultivation there were two split-root treatments in which fertigation solution concentrations were reversed in intervals to improve functioning of root systems. Effects of different EC combinations on vegetative growth between above- and underground parts of greenhouse cucumber and morphology and anatomy of roots were studied in a separate experiment. Results demonstrated that split-root cultivation increased cucumber yields up to 16% but had no effect on uptake of water or nutrients over the whole cultivation period. The most of spiked fruits were formed in single-root cultivation which refers to water supply problems during the highest need for transpiration. The technique didn’t affect plants’ vegetative growth or structure. Petiole sap nitrate and potassium analyses indicated that nutrient concentrations of fertigation solutions had no effect on nutrient uptake of roots. Different EC combinations had a greater effect on root weight than on shoot weight or stem growth in greenhouse cucumber. Petiole sap analyses suggested that nutrients were allocated variously in different EC combinations. The osmotic stress caused by high ECs led to changes in root morphology and anatomy. Results indicated that split-root cultivation enhanced the sink strength of developing fruits in relation to other sinks without affecting vegetative growth. When sides of fertigation solutions of low and high EC were switched during cultivation, the root system was able to take water and nutrients flexibly and economically, in which case significant yield increases were achieved in greenhouse cucumber production. Splitting root system probably affects plants’ hormone metabolism and can impair growth of roots without impairing their functioning, whereupon assimilates are allocated more efficiently to the growth of aboveground plant parts.