Determination of manganese with Methylene Blue in various vegetable crops

H.P. Beck, D. Kostova and B. Zhang

Inst. Inorg. Anal. Chem. Radiochem.,Saarland Univ. Saarbrucken, D-66123, Germany

Abstract:

A study was made of the manganese content in the crop production of 28 vegetable species, using the most common cultivars within the species. The manganese content was determined by a new extraction – spectrophotometric method using Methylene Blue (MB). The ion – associate of Mn(VII) was completely removed in a single extraction of only 5 s, and the 1,2-dichloroethane layer remained constant for 2 days under the usual laboratory conditions. To compare results, manganese was determined by the atomic – absorption method. The results obtained showed that the manganese content varies significantly in the different vegetable species and cultivars. The manganese content in more widely used varieties of tomatoes, peppers, head cabbage, melons, and radishes was studied in order to establish differences with respect to the level of this element in their production.

Key words:

Fungal characteristics and varietal reactions of powdery mildew species on cucurbits in the steppes of Ukraine

Y. Tomason¹ and P.T. Gibson²

¹Department of Selection and Seed Production, Dnepropetrovsk State Agrarian University,Voroshilov 25, 49600 Dnepropetrovsk, Ukraine; e-mail: yantomason75@mail.ru
² Department of Plant, Soil and Agriculture Systems, Southern Illinois University, 62901,Carbondale, IL, USA; e-mail: pgibson@siu.edu

Abstract:

Powdery mildew caused by fungal species Sphaerotheca fuliginea (Schlect ex. Fr.) Poll. [syn. Podosphaera xanthii (sect. Sphaerotheca) xanthii (Castag.) U. Braun & N. Shish. Comb. nov.] and Erysiphe cichoracearum D.C. [syn. Golovinomyces cichoracearum (D.C.) Huleta] is the most frequent cucurbit (Cucurbitaceae) crop disease in the northern steppes of Ukraine. Species commonly cultivated in Ukraine (melon, watermelon, squash) were colonized by both species. Ash gourd (Benincasa hispida Cogn.) and bottle gourd (Lagenaria siceraria Standl.) were colonized only by E. cichoracearum. Sponge gourd (Luffa cylindrica M.J. Roem) and fig-leaved gourd (Cucurbita ficifolia L.) were not colonized by either of these fungi. Varieties within species varied from resistant to highly susceptible. Four melon varieties were agronomically elite and had resistance to both species. Those two species were consistently differentiated by the location on the conidia where germination occurred, and by the ratio of conidial length to width. Indicator host species and varieties can provide a tentative identification of which powdery mildew species are present in the field.Varietal differentials suggested that races 1 & 2 of S. fuliginea were present onwatermelon, and that race 1 and at least one other race were present on melon.

Key words:

Citrullus lanatus, Cucumis melo, cucurbit, Cucurbitaceae, Erysiphe cichoracearum, melon, powdery mildew, races, resistance, Sphaerotheca fuliginea, watermelon