Impact of field dodder (Cuscuta campestris Yunk.) on physiological and anatomical changes in untreated and herbicide-treated alfalfa plants

Abstract

The effects of field dodder on physiological processes and the anatomy of alfalfa plants were examined under controlled conditions. The experiment included the following variants: N - noninfested alfalfa plants (control); I - infested alfalfa plants (untreated); T - infested plants treated with imazethapyr. Imazethapyr application rate was 100 g a.i. ha-1. The following parameters were checked: physiological - pigment content (chlorophyll ɑ, chlorophyll b, total carotenoids); anatomical - stem parameters: thickness of epidermis and cortex, and diameter of stem and central cylinder; leaf parameters: thickness of epidermis, parenchyma and spongy tissue, mesophyll and underside leaf epidermis, and diameter of bundle sheath cells in alfalfa plants. Pigment contents and anatomical parameters were measured: prior to herbicide treatment (0 assessment), then 7 (I assessment), 14 (II assessment), 21 (III assessment), 28 (IV assessment) and 35 (V assessment) days after application (DAA). Field dodder was found to affect the contents of chlorophyll ɑ, chlorophyll ɑ and carotenoids in untreated alfalfa plants, causing significant reductions in pigment content. Conversely, percent reduction in the treated plants decreased 22-5% for chlorophyll ɑ, 25-1%, for chlorophyll b, and 21-11% for carotenoids, while a stimulating effect of 1-6% was observed for the contents of chlorophyll b and carotenoids 35 DAA. Plants infested (untreated) by field dodder had lower values of most anatomical parameters, compared to noninfested plants. The measured anatomical parameters of alfalfa stems and leaves had significantly higher values in noninfested plants and plants treated with imazethapyr than in untreated plants.

Uticaj viline kosice na anatomske i fiziološke promene kod biljaka lucerke ispitivan je u kontrolisanim uslovima. Praćene su sledeće varijante: N - nezaražene biljke lucerke (kontrola); I- zaražene biljke lucerke i zaražene biljke lucerke tretirane sa imazetapirom (T). Imazetapir je primenjen u količini od 100 g a.i. ha-1. Mereni su sledeći parametri: fiziološki - sadržaj pigmenata (hlorofil ɑ, hlorofil b i ukupni karotenoidi); anatomski - stablo: debljina epidermisa i primarne kore stabla, prečnik centralnog cilindra i prečnik stabla; list: debljina epidermalnih ćelija lica i naličja lista, debljina parenhimskog i sunđerastog tkiva, debljina mezofila i prečnik ćelija omotača provodnih snopića. Sadržaj pigmenata i anatomski parametri su mereni: pre primene herbicida (0 ocena), potom 7, 14, 21, 35 dana nakon primene herbicida. Vilina kosica je prouzrokovala značajnu redukciju sadržaja pigmenata kod netretiranih biljaka lucerke. Nasuprot ovome, kod tretiranim biljaka lucerke procenat redukcije se smanjivao od 22­5% za hlorofil ɑ, 25-1%, za hlorofil b i 21-11% za karotenoide, dok je za hlorofil ɑ i karotenoide 35 dana nakon primene herbicida zabeležen stimulativni efekat od 1-6%. Biljke zaražene vilinom kosicom (netretirane) su imale značajno manje vrednosti za sve merene anatomske parametare u odnosu na tretirane. Naime, mereni anatomski parametri stabla i lista lucerke su značajno veći kod kontrolnih biljaka i tretitanih sa imazetapirom u odnosu na netretirane.