Disponibilidade hídrica e sazonalidade afetam a fitomassa e pigmentos fotossintéticos de Aloysia citrodora Paláu

Vegetative growth can be affected by different environmental factors. The objective of this work was to evaluate phytomass production and photosynthetic pigments of Aloysia citrodora plants submitted to different irrigation levels and seasons. The experiment was carried out in a protected environment from August 2015 to March 2017, in an experimental randomized blocks design, 4x4 factorial scheme, with four blocks with four plants each. The irrigation levels tested were 25%, 50%, 75% and 100% of the field capacity, in the four seasons of the year (autumn, winter, spring and summer). Plant height, fresh and dry mass of branches, fresh and dry mass of leaves, leaf area and photosynthetic pigments (chlorophyll a, chlorophyll b and carotenoids) were evaluated. It was observed that water availability and seasons influence phytomass production as well as the photosynthetic pigment analyzes. Low irrigation levels and cultivation during autumn and winter adversely affect vegetative growth. Furthermore, our results indicate that for higher phytomass production, it is recommended to cultivate Aloysia citrodora during spring and summer under irrigation levels of 75% and 100% of field capacity. Spring season promotes higher content of photosynthetic pigments. This study will open new avenues and perspectives to elucidate possible changes in secondary metabolites of Aloysia citrodora, a medicinal plant, in the presence of changes in the growing seasons and different stress conditions, including water stress.O crescimento vegetativo pode ser afetado por diferentes fatores ambientais. O objetivo deste trabalho foi avaliar a produção de fitomassa e pigmentos fotossintéticos de plantas de Aloysia citrodora submetidas a diferentes níveis de irrigação e estações do ano. O experimento foi realizado em ambiente protegido, no período de agosto de 2015 a março de 2017, em delineamento experimental de blocos casualizados, em esquema fatorial 4x4, com quatro blocos com quatro plantas cada. Os níveis de irrigação testados foram de 25%, 50%, 75% e 100% da capacidade de campo, nas quatro estações do ano (outono, inverno, primavera e verão). Foram avaliadas a altura das plantas, massa fresca e seca de ramos, massa fresca e seca de folhas, área foliar e pigmentos fotossintéticos (clorofila a, clorofila b e carotenoides). Observou-se que a disponibilidade hídrica e as estações do ano influenciam a produção de fitomassa e as análises de pigmentos fotossintéticos. Baixos níveis de irrigação e cultivo durante o outono e inverno afetam adversamente o crescimento vegetativo. Portanto, nossos resultados indicam que para maior produção de fitomassa, recomenda-se o cultivo de Aloysia citrodora durante a primavera e o verão sob níveis de irrigação de 75% e 100% da capacidade de campo. A estação da primavera promove maior conteúdo de pigmentos fotossintéticos. Este estudo abrirá novos caminhos e perspectivas para elucidar possíveis alterações nos metabólitos secundários de Aloysia citrodora, uma planta medicinal, quando submetida a mudanças nas estações de cultivo e nas diferentes condições de estresse, como o estresse hídrico

Viabilidade do extrato aquoso de Cyperus rotundus como indutor de enraizamento em estacas de videira em comparação com hormônios sintéticos

O objetivo do trabalho foi avaliar o efeito do extrato aquoso de tubérculos de tiririca (Cyperus rotundus), comparando-o com a ação dos hormônios vegetais ácido indolbutírico e ácido naftalenoacético, em estacas de videira (Vitis vinifera L. [var. Bordô e Niágara]). O experimento foi conduzido em delineamento inteiramente casualizado, em esquema fatorial 2 x 4, sendo duas variedades (Bordô e Niágara) e quatro indutores de enraizamento (ácido indolbutírico, ácido naftalenoacético, extrato aquoso de tiririca e água destilada – controle). Após 125 dias de condução do experimento, foram avaliados: número de folhas, número de raízes, número de brotos, comprimento da raiz, comprimento da parte aérea e massa seca da raiz e das folhas. O extrato aquoso de tiririca promoveu resultados satisfatórios sobre o número de brotos e o comprimento de raízes, não diferindo estatisticamente dos hormônios vegetais sintéticos. Entretanto a resposta foi diferente entre as variedades, não ocasionando incremento significativo de massa seca de raiz e de folhas. O número de folhas das variedades de videira é dependente do genótipo, assim como a matéria seca de raiz e de folhas. O extrato aquoso de tiririca pode ser uma alternativa sustentável para promover o enraizamento de estacas, em função da presença de substâncias que estimulam o enraizamento.

Desenvolvimento inicial de mudas de Eugenia involucrata DC. sob diferentes substratos

A qualidade da produção de mudas de espécies florestais é afetada pela composição do substrato. Diante disso, o objetivo do estudo foi avaliar o desenvolvimento inicial de mudas de cerejeira (Eugenia involucrata DC.) sob diferentes composições de substrato. O experimento foi conduzido em vasos no interior de ambiente protegido da Universidade Federal de Santa Maria, Campus Frederico Westphalen, em delineamento inteiramente casualizado, constituído de cinco tratamentos com seis repetições.  Os tratamentos consistiram de diferentes composições de substratos, sendo: T1- 45% de solo + 45% de areia + 10% de vermiculita; T2- 45% de solo + 45% de areia + 10% de vermiculita + 108 g de Osmocote®; T3- 35% de solo + 35% de areia + 10% de vermiculita + 20% de cama de aves; T4- 35% de solo + 35% de areia + 10% de vermiculita + 20% de esterco bovino; T5- 35% de solo + 35% de areia + 10% de vermiculita + 20% de composto suíno. As variáveis avaliadas foram altura de plantas, diâmetro de caule, massa fresca e seca de raiz e massa fresca e seca de parte aérea. Os resultados demonstraram que a composição dos substratos influenciou sobre o desenvolvimento inicial das mudas de cerejeira, apresentando variações em relação as variáveis avaliadas. Por fim, conclui-se que o substrato composto por 45% de solo + 45% de areia + 10% de vermiculita + 108 gramas de Osmocote® proporciona maiores incrementos de fitomassa nas plantas, sendo recomendado para produção de mudas de cerejeira

Technical feasibility of minicutting of different portions of the branch to produce clonal seedlings of Aloysia citrodora

Seedling production using the minicutting technique enables quick and efficient plants formation. However, there are no reports of application for Aloysia citrodora (lemon verbena) and the ideal portion of the branch. This study aimed to evaluate the production of seedlings from minicuttings taken from different parts of the branch.The experiment was performed in a completely randomized design. Three treatments consisted of minicuttings taken from other branch portions (basal, median, and apical), divided into two experiments (Exp1 and Exp2).Exp1 was carried out in a sub-irrigation system in phenolic foam, evaluating rooting percentage, length of the longest root, root number, number of shoots, number of leaves, and total dry mass. Exp2 used the minicuttings from the previous experiment, kept for another 35 days in pots to assess the quality of the seedlings, evaluating plant length, number of shoots, and leaves. For Exp1, 35 days after cutting, there was a higher percentage of survival, size of the longest root, number of the root, number of shoots, number of leaves, and total dry mass, in those minicuttings produced from the basal and median portions, being the exact behavior of Exp2, 35 days after transplantation to pots. The minicutting proved to be an efficient method for producing Aloysia citrodoraseedlings, when removed from the basal or median portion, standing out for a higher percentage of survival, better growth, and initial development and post-transplantation of the produced seedlings.Seedling production using the minicutting technique enables quick and efficient plants formation. However, there are no reports of application for Aloysia citrodora (lemon verbena) and the ideal portion of the branch. This study aimed to evaluate the production of seedlings from minicuttings taken from different parts of the branch.The experiment was performed in a completely randomized design. Three treatments consisted of minicuttings taken from other branch portions (basal, median, and apical), divided into two experiments (Exp1 and Exp2).Exp1 was carried out in a sub-irrigation system in phenolic foam, evaluating rooting percentage, length of the longest root, root number, number of shoots, number of leaves, and total dry mass. Exp2 used the minicuttings from the previous experiment, kept for another 35 days in pots to assess the quality of the seedlings, evaluating plant length, number of shoots, and leaves. For Exp1, 35 days after cutting, there was a higher percentage of survival, size of the longest root, number of the root, number of shoots, number of leaves, and total dry mass, in those minicuttings produced from the basal and median portions, being the exact behavior of Exp2, 35 days after transplantation to pots. The minicutting proved to be an efficient method for producing Aloysia citrodoraseedlings, when removed from the basal or median portion, standing out for a higher percentage of survival, better growth, and initial development and post-transplantation of the produced seedlings

Base temperature and plastochron are influenced by the development phase in biquinho pepper cultivars

The objective was to estimate the base temperature and determine the plastochron for Capsicum chinense cultivars during the vegetative and reproductive development phases at different planting times. The experiment was conducted in a randomized block design, 2x4 factorial scheme, cultivars of biquinho pepper (“BRS Moema”, “Airatema Biquinho Amarela”) and growing seasons (E1-E2-E3-E4). The Air temperature was monitored during the vegetative and reproductive phases of the crop. Tb was determined by the minimum mean square error method (QMe). For both phases of the crop development, plastochron was determined by linear regression between the number of nodes and the accumulated thermal sum (Sta). Tb and plastochron were not influenced by the cultivar. In the vegetative phase, Tb and plastochron were dependent on the sowing season, presenting on average Tb (16.8°C) and plastochron (43.6°C day-1). In the reproductive phase both Tb and plastochron were similar at all sowing times, with averages of 16.7°C and 64.4°C day-1 plastochron, for base temperature and plastochron, respectively. Therefore, the emission of nodes is not influenced by the cultivar, but by growing season. With the plastochron values found it is concluded that the development of biquinho pepper is more accelerated during the vegetative phase than the reproductive one.The objective was to estimate the base temperature and determine the plastochron for Capsicum chinense cultivars during the vegetative and reproductive development phases at different planting times. The experiment was conducted in a randomized block design, 2x4 factorial scheme, cultivars of biquinho pepper (“BRS Moema”, “Airatema Biquinho Amarela”) and growing seasons (E1-E2-E3-E4). The Air temperature was monitored during the vegetative and reproductive phases of the crop. Tb was determined by the minimum mean square error method (QMe). For both phases of the crop development, plastochron was determined by linear regression between the number of nodes and the accumulated thermal sum (Sta). Tb and plastochron were not influenced by the cultivar. In the vegetative phase, Tb and plastochron were dependent on the sowing season, presenting on average Tb (16.8°C) and plastochron (43.6°C day-1). In the reproductive phase both Tb and plastochron were similar at all sowing times, with averages of 16.7°C and 64.4°C day-1 plastochron, for base temperature and plastochron, respectively. Therefore, the emission of nodes is not influenced by the cultivar, but by growing season. With the plastochron values found it is concluded that the development of biquinho pepper is more accelerated during the vegetative phase than the reproductive one