Análise morfológica de Sagittaria montevidensis desenvolvida em diferentes condições de inundação

Abstract

RESUMO -O cultivo de arroz irrigado em sistema pré-germinado tem permitido o desenvolvimento de plantas daninhas aquáticas, como as da espécie Sagittaria montevidensis (sagitária), a qual desenvolveu biótipos resistentes a herbicidas inibidores de ALS, no Estado de Santa Catarina. No presente trabalho, objetivou-se examinar as respostas morfológicas de sagitária quanto à variação da lâmina d'água, crescendo sob condições ambientais controladas. Os tratamentos foram representados pelas seguintes condições de inundação: solo saturado, 5, 10 e 20 cm de submersão, em delineamento experimental completamente casualizado, com cinco repetições. A presença de lâmina d'água favoreceu a germinação das sementes de sagitária. O aumento da profundidade de submersão incrementou a estatura da planta por meio do alongamento dos pecíolos das folhas espatuladas e sagitadas. Variação na profundidade da lâmina d'água não modificou o número de plantas, a massa seca, o número de folhas e de raízes, o tamanho da folha linear, o tamanho da lâmina foliar espatulada e sagitada e do escapo floral das plantas de S. montevidensis. As folhas de sagitária de mesmo tipo morfológico, quando desenvolvidas nas profundidades de água testadas, não diferiram histologicamente.Palavras-chave: germinação, manejo, níveis de água, plantas daninhas, sagitária.ABSTRACT -The cultivation of irrigated rice under water-seeded rice system has allowed the development of aquatic weed plants such as Sagittaria montevidensis (giant arrowhead), which has developed biotypes resistant to ALS-inhibiting herbicides in the state of Santa Catarina. This research aimed to investigate the morphologic responses of giant arrowhead to water level variation, under controlled environmental conditions. The treatments were represented by the following flood conditions: saturated soil, 5, 10 and 20 cm of water submersion, arranged in a completely randomized design, with five repetitions. Seed germination was promoted by the presence of water. Submersion depth increased plant height through petide lengthening of the spatulate and sagittate foliar blade size leaves. Water sheet depth variation did not modify the number of plants, dry mass, the number of leaves and roots, linear leaf size, spatulate and sagittate foliar blade size and the inflorescence axis of the S. montevidensis plants. The giant arrowhead leaves of the same morphological type did not differ histologically when developed under the tested water depths.

Weed phytosociological in irrigated rice under different cultivation systems and crop rotation intensity

“…Regarding aquatic species, Sagittaria montevidensis stands out because it is a rhizomatous species which adapts to the ecological amplitude. When it is not controlled, a broad amount of seeds can develop on the soil and contribute to increase the population in the next season (CASSOL et al, 2008).…”

Water level-dependent morphological plasticity in Sagittaria montevidensis Cham. and Schl. (Alismataceae).

“…This may be related to the absence of histological differentiation of plant tissues under different water levels. Cassol et al (2008) showed that increases in water levels did not lead to the synthesis of secondary cell walls. In our study, however, plants were submitted to a strong water flow during flood periods, which may have caused the investment in greater basal areas, petiole diameter and petiole biomass.…”

“…Structures such as leaves and petioles can suffer changes in number, length, biomass and diameter in response to environmental variations, such as water level fluctuations (Cassol et al, 2008). Major key life-history traits that suffer morphological changes enhancing the survival of such plants include: tissues elongation, new leaves recruitment, petioles and basal plant diameters, and emergent surface area (Cooling et al, 2001;Deegan et al, 2007;Iwanaga and Yamamoto, 2008;Xie et al, 2008;Li et al, 2011).…”

“…So, water level fluctuations may represent a good alternative for macrophyte population management, but scarcely information is found about its effects on S. montevidensis. Laboratory studies by Cassol et al (2008) showed that S. montevidensis presents morphologic changes under flood conditions. However, in that work, the maximum water level used in the treatments was 20 cm above ground, which may not cover a great range of water level fluctuations that occur in field conditions.…”

Chemical control of California arrowhead (Sagittaria montevidensis) resistant to acetolactate synthase and photosystem II inhibiting herbicides in irrigated rice

“…Grande do Sul (RS), where the system of pregerminated seeding is used (CASSOL et al, 2008). Chemical control has been widely used in SC for the control of S. montevidensis, with at least one herbicide application during the rice crop season.…”