Genetic foci of Solanum species, Petota Dumort, resistant to Phytophthora infestans (Mont.) De Bary

The present paper provides a review of data from literature sources and results of research carried out at the Institute of PlantIndustry with the aim of identifying genetic centres of formation of late blight resistant genotypes. For the research results, speciesfrom the potato collection of VIR were used.     

The Effect of Soil pH and Manganese Toxicity Upon the Growth and Mineral Composition of the Hop Plant

Summary

The productivity of ornamental foliage plants is related to their capacity to increase their leaf number and leaf size. In Monstera deliciosa, a change in leaf shape is also a pre-requisite for successful marketing. The aim of this work was to describe the effects of different concentrations of exogenous 6-benzylaminopurine (BAP; 5, 50, 100, or 200 mg l^–1) on the control of both leaf size and leaf shape in M. deliciosa, and the impact of these changes on commercial plant productivity. We found an increase of between 15.4 – 23.1% in the rate of leaf appearance (RLA), which reflected a shortening of the phyllochron, and an increase of between 17.5 – 34.9% in the relative rate of leaf area expansion (RLAE) at most of the BAP concentrations tested. This resulted in higher biomass accumulation in both roots and shoots through an increase of between 5.4 – 7.9% in the relative growth rate (RGR), mainly associated with higher net assimilation rates (NAR; increases from 9.0-fold to 11.0-fold) and increased photoassimilate partitioning to the shoots. The most important result of this work was the early appearance of perforated leaf laminae in M. deliciosa plants sprayed with 50 – 200 mg l^–1 BAP, which made them ready for sale.     

The effect of nitrogenous compounds on in vitro germination of Orobanche crenata Forsk.

The effect of nitrogen (ammonium, urea and nitrate), applied during a conditioning or germination phase, on germination of Orobanche crenata Forsk, seeds was investigated in vitro. Ammonium sulphate (8 mM) applied during conditioning in combination with the nitrification inhibitor nitrapyrin, reduced germination of seeds from 46% to 26%. A lower concentration of 4 mM ammonium sulphate or supplying nitrogen as 8 mM urea or 16 mM nitrate did not inhibit germination. Applied after conditioning during the germination phase, 4 mM ammonium sulphate strongly inhibited germination, especially in combination with a nitrification inhibitor: germination was reduced to less than 5%. Urea (8 mM) reduced germination to only a limited extent (from 58% to 40%). When a urease inhibitor (carbon disulfide) was additionally applied, germination percentage was not affected. Nitrate had no effect. It is hypothesized that the inhibition by ammonium of O. crenata germination is connected with a reduced ability to detoxify ammonium, owing to the reduced activities of the enzymes GS and GOGAT. The inhibitory effect of urea may be indirect, occurring through conversion to ammonium. The effect of a short-term exposure to ammonium was largely reversible and no increase in mortality could be detected. The presence of 6 mM phosphate, Hepes or Mops buffer was found to intervene with the inhibition by ammonium.