Effect of Benlate and Rhizoctonia interactions on the growth, chlorophyll contents and nitrogen fixation in three species of Azolla

Abstract

Azolla is an aquatic fern that fixes atmospheric nitrogen in symbiotic association with the cyanobacterium Anabaena azollae. Azolla fronds are commonly affected by a soil-borne pathogen, namely Rhizoctonia solani. Benlate, a systemic fungicide, was used for treating three species of Azolla with a view to assessing its effect on growth, chlorophyll synthesis and nitrogen-fixing potential besides checking the Rhizoctonia solani infection. Benlate at 2.5 p.p.m. induced the growth of Azolla microphylla – BR–GI, Azolla caroliniana – WT–V and Azolla sp. – ST–SI. The growth rate induction in Azolla sp. – ST–SI due to Benlate treatment was significant. The culture Azolla sp. – ST–SI showed maximum nitrogenase activity due to Benlate treatment, followed by A. microphylla – BR–GI. A. caroliniana – WT–V and Azolla sp. – ST–SI, when treated with Benlate, have shown higher chlorophyll. Benlate treatment reduced the nitrogen content in A. microphylla – BR-GI and Azolla sp. – ST–SI, while carbon content was not affected much. Azolla is ’n watervaring wat atmosferiese stikstof bind in simbiotiese assosiasie met die sianobakterie Anabaena azollae. Azolla blare word algemeen aangetas deur die grondpatogeen Rhizoctonia solani. Benlate, ’n sistemiese swamdoder, is gebruik om drie Azolla spesies te behandel, nie net om die Rhizoctonia solani infeksie te stuit nie, maar ook om die uitwerking daarvan op die groei, chlorofilsintese en stikstofbindingspotensiaal te bepaal. Benlate, teen 2.5 d.p.m., het die groei van Azolla microphylla – BR–GI, Azolla caroliniana – WT–V en Azolla sp. – ST–SI geïnduseer. Die groeitempo-induksie by Azolla sp. – ST–SI as gevolg van Benlate-behandeling was betekenisvol. Die kultuur Azolla sp. – ST–SI het maksimum nitrogenase-aktiwiteit as gevolg van Benlate-behandeling getoon, gevolg deur A. microphylla – BR–GI. Wanneer met Benlate behandel, het A. caroliniana – WT–V en Azolla sp. – ST–SI hoër chlorofil getoon. Benlate-behandeling het die stikstofinhoud van A. microphylla – BR–GI en Azolla sp. – ST–SI verminder, terwyl die koolstofinhoud nie veel beïnvloed is nie.