Phenology and thermal requirements of the species Cyperus difformis L. in southern Brazil

Higor Modesto Garlet Voss,Elisandro Azeredo Nunes,Vinicius Severo Trivisiol,Sylvio Henrique Bidel Dornelles,Jaíne Rubert,Mariane Peripolli,Otávio dos Santos Escobar,Maicon Pivetta

doi:10.4025/actascibiolsci.v43i1.47560

Higor Modesto Garlet Voss, Elisandro Azeredo Nunes + Show 6 more

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https://doi.org/10.4025/actascibiolsci.v43i1.47560

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Abstract

Cyperus difformis L. is a Cyperaceae, annual, of natural occurrence in marshy environments in southern Brazil, considered a weed in irrigated rice crops. Studies on its development are scarce, especially regarding its cycle and thermal requirements. Therefore, the objective of this work was to determine the base temperature, the thermal sum and the duration of the different sub-periods of the biological cycle of the species. The experiment was carried out at the Campus of the Universidade Federal de Santa Maria – UFSM, Santa Maria, Rio Grande do Sul, in four sowing seasons. In a completely delineated design and factorial scheme involving five soil water conditions (water depth and 50% soil water retention capacity [WRC]) from the sowing, water depth and 50% WRC introduced 21 days after emergence and 100% WRC during the whole cycle, with six repetitions each. Each experimental unit consisted of a cultivated in pot plant with 11 L capacity filled with soil. The cycle of the plants was subdivided into the sowing-emergence sub-periods, emergence-emission of the floral tassel and emission of the floral-maturing physiological tassel, being estimated the thermal requirements for the species. The conditions of the soil water condition the base temperature, the sum of the degree-days and the duration of the species cycle. The base temperature varies for each treatment, the sum of degrees-day decreases with the water deficit and the plants under flood accelerate the biological cycle.

Highlights

IntroductionThe species Cyperus difformis L. is considered an invasive plant in rice fields in southern Brazil, mainly in the pre-germinated crop system
The species C. difformis has the capacity to develop in flooded environments, despite presenting a C3 photosynthetic mechanism, which is not the most efficient, it finds in this environment the best conditions for its development, being possible to produce a large amount of energy and to advance its cycle (Taiz, Zeiger, Møller, & Murphy, 2017) in such a way that species can develop more than one cycle in relation to that of irrigated rice
The species is not adaptable to emergence in drier environments, and it may be that information, pertinent to rice farmers, since through physical management such as drainage of the areas in the off-season and pre-sowing, would significantly reduce the infestation of the invasive plant and, the initial competition with the irrigated rice in its initial phase of development

Summary

Introduction

The species Cyperus difformis L. is considered an invasive plant in rice fields in southern Brazil, mainly in the pre-germinated crop system. This system is preferably used to physically control species with a high level of resistance that are established during the cultivation cycle, especially at its beginning. Herbicide resistance was observed, mainly in the chemical group of inhibitors of the enzyme Acetolactate Synthase (ALS) (Vargas et al, 2016), which is widely used in rice cultivation in southern Brazil

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