Effects of P level in nutrient solution and the colonization of roots by arbuscular mycorrhizal fungi (AMF) on P uptake by tomato plants, their nutritional status, yield and quality of fruits were studied. Plants were grown on rockwool or coconut coir. Inoculation by a mixture of several AMF species was performed three times during the growing period. The mycorrhizal frequency in roots inoculated with AMF amounted to 35.79 – 50.82%. The highest level of mycorrhiza was found in plants receiving nutrient solution with a lower concentration of P. Among the experimental factors, only P level influenced the fruit yield, being higher from plants receiving a nutrient solution with a higher P level. A higher concentration of P in nutrient solution imposed better nutritional status of plants. Higher contents of ascorbic acid and total soluble sugars were found in fruits collected from inoculated plants, grown on rockwool.

Kowalska I., Konieczny A., Gąstoł M. 2015. Effect of mycorrhiza and the phosphorus content in a nutrient solution on the yield and nutritional status of lettuce grown on various substrates. J. Elem., 20(3): 631-642. AbstractThe potential of mycorrhization of lettuce in hydroponic conditions was tested in a two-year experiment carried out in the autumn of 2011 and 2012 in an unheated foil tunnel. The experimental factors were as follows: inoculation of plants with arbuscular mycorrhizal fungi (AMF+ or AMF-), concentration of phosphorus in a nutrient solution (10 or 40 mg dm -3 ) and the type of substrate (rockwool or coconut coir). The inoculation of plants with arbuscular mycorrhizal fungi of the genus Glomus was performed twice, i.e. while sowing seeds and when planting lettuce plants into mats. The impact of the experimental factors on the degree of colonization of lettuce roots by AMF as well as the yield and nutritional status of plants, expressed as the content of macro-and micronutrients, was studied. The mycorrhizal frequency in roots inoculated with AMF reached 51.36%. The nutrient solution concentration of phosphorus and the type of substrate did not have any significant effect on the mycorrhizal frequency. There were no differences in the yield and content of macronutrients in lettuce leaves between plants inoculated and not inoculated with AMF (AMF+, AMF-). Likewise, there were no differences in the yield caused by different phosphorus levels in the nutrient solution or the types of substrate. Plants growing on rockwool accumulated significantly less P, Ca and Mg in comparison to plants growing on coconut coir. Regarding Ca, this effect was especially pronounced in plants receiving the nutrient solution with a higher concentration of P, i.e. 40 mg dm -3 . Mycorrhiza had a significant effect on the content of Cu, Mn and Zn in lettuce leaves. Inoculated plants were characterized by a lower content of these micronutries compared to plants grown without AMF. With respect to Mn, this effect was particularly evident in plants grown on rockwool.

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Lettuce plants were grown in the foil tunnel in pots filled with peat substrate. The experimental factors were: concentration of phosphorus in the substrate (70 or 140 mg dm-3), inoculation of substrate with arbuscular mycorrhizal fungi (+AMF or –AMF) and concentration of selenium in the substrate (0, 6 or 12 mg dm-3). Mycorrhizal frequency in roots was affected by concentration of P, inoculation with AMF and interaction between these factors. Higher mycorrhizal frequency was found in plants inoculated with AMF and grown under conditions of lower P concentration. AMF did not affect an accumulation of Se in leaves. However, higher concentration of P and Se in the substrate affected Se concentration in leaves. The average yield of lettuce decreased with increasing level of Se in the substrate. The presence of Se in the substrate led to decrease of K, Mg, Fe, Cu and Mn content of plants. AMF did not have an effect on the content of sugars in leaves.

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