Crescimento e metabolismo de mudas de Pityrocarpa moniliformis Benth. sob deficit hídrico

Pityrocarpa moniliformis Benth. has medicinal properties, forage potential, besides showing rusticity and rapid growth, which confer potential to recover degraded areas. In this context, the objective was to evaluate the growth and biochemical components of Pityrocarpa moniliformis seedlings under water deficit conditions. The design used was randomized blocks, with five treatments and four replicates, with the experimental plot consisting of twenty plants. Treatments were characterized by different periods of water deficit (0; 4; 8; 12 and 16 days without irrigation). At 44 days after sowing (DAS), when the seedlings had two pairs of fully formed true leaves, the treatments began to be applied. The development of the seedlings was evaluated until 60 DAS when they were collected for biometric and biochemical analyses. The variables analyzed were shoot height; collar diameter; number of leaves; shoot dry mass; root dry mass; root/shoot ratio; and Dickson’s quality index. Contents of total chlorophyll, chlorophyll a, chlorophyll b, total free amino acids, total soluble sugar, and proline contents in the leaves were also determined. The treatment most affected by the lack of irrigation was 16 days of water deficit, which resulted in the death of 38.8% of the seedlings. This condition caused a decrease in shoot length, reducing it by approximately 29.2% compared to the control treatment. There was also a reduction in the production of new leaves from the eighth day after the differentiation of treatments. Pityrocarpa moniliformis seedlings can develop under the condition of water deficit for up to 8 days, even with chlorophyll degradation due to stress. Pityrocarpa moniliformis maintains its vegetative development by performing osmotic adjustment through the accumulation of biomolecules (sugars, proline, and amino acids).Pityrocarpa moniliformis Benth. possui propriedades medicinais, potencial forrageiro, além de apresentar rusticidade e rápido crescimento, o que lhe confere potencialidade de uso para recuperação de áreas degradadas. Nesse contexto, objetivou-se avaliar o crescimento e os componentes bioquímicos de mudas de Pityrocarpa moniliformis em condições de deficit hídrico. O delineamento foi em blocos casualizados, com cinco tratamentos e quatro repetições, sendo a parcela experimental composta por vinte plantas. Os tratamentos foram caracterizados por diferentes períodos de deficit hídrico (0; 4; 8; 12 e 16 dias sem irrigação). Aos 44 dias após a semeadura (DAS), quando as mudas apresentaram dois pares de folhas verdadeiras totalmente formadas, iniciou-se a aplicação dos tratamentos. O desenvolvimento das mudas foi avaliado até os 60 DAS, período em que ocorreu a coleta destas para as análises biométricas e bioquímicas. As variáveis analisadas foram: altura da parte aérea; diâmetro do colo; número de folhas; massa seca de parte aérea e raiz; relação entre raiz e parte aérea; e índice de qualidade de Dickson. Também foram determinados nas folhas os teores de clorofilas totais, a e b; aminoácidos livres totais; teor de açúcares solúveis totais; e teor de prolina. O tratamento mais afetado pela falta de irrigação foi o de 16 dias, o qual acarretou a morte de 38,8% das mudas. Essa condição ocasionou a diminuição no comprimento da parte aérea das mudas, com redução de aproximadamente 29,2%, quando comparado ao tratamento-controle. Houve também redução da emissão de novas folhas a partir do oitavo dia após a diferenciação dos tratamentos. Mudas de Pityrocarpa moniliformis conseguem se desenvolver em condição de deficit hídrico por até 8 dias, mesmo ocorrendo a degradação de clorofilas devido ao estresse. A manutenção do desenvolvimento vegetativo de Pityrocarpa moniliformis ocorre devido à realização de ajustamento osmótico pelo acúmulo de biomoléculas (açúcares, prolina e aminoácidos)

PRE-GERMINATION TREATMENT OF CARROT SEEDS WITH BIOACTIVATOR

Carrot is a vegetable with an important socio-economic role, both due to the employment of labor and high commercialization. To optimize the establishment of this crop in fields, seeds with rapid and uniform germination are essential. Therefore, various seed treatment techniques have been used to enable and enhance the germination percentage and optimize the vigor of the seeds. In continuation with this, the objective of this study was to evaluate the effects of thiamethoxam on the physiological performance of carrot seeds during germination and initial development of seedlings. The experimental design was a completely randomized design in a 5 × 4 factorial scheme, with five carrot cultivars and four doses of thiamethoxam (0, 0.4, 0.8, and 1.2 mL). Parameters such as germination, first germination count, seedling length, and dry mass were evaluated. In addition, biochemical analyses of total sugars, total amino acids, and proline content were performed. In general, the treatment of carrot seeds with thiamethoxam positively influenced the germination of the seeds of the cultivars studied. However, thiamethoxam doses of 0.4 and 0.8 mL had no positive effect on the seedling development of the Tropical cultivar. The thiamethoxam dose of 1.2 mL was beneficial to the development of seedlings and accumulation of metabolites in the Alvorada cultivar.A cenoura é uma hortaliça com papel socioeconômico importante, tanto pelo elevado emprego de mão-de-obra, quanto por sua alta comercialização. Para otimizar o estabelecimento dessa cultura em campo se torna imprescindível sementes com germinação rápida e uniforme. Por isso, tem-se utilizado o tratamento de sementes como técnica para viabilizar o desempenho germinativo e expressão de vigor. Desse modo, objetivou-se avaliar os efeitos do tiametoxam no desempenho fisiológico de sementes de cenoura durante a germinação e desenvolvimento inicial de plântulas. O delineamento experimental foi o inteiramente casualizado, em esquema fatorial 5 x 4, sendo cinco cultivares de cenoura e quatro dosagens de tiametoxam (0; 0,4; 0,8 e 1,2 mL). Avaliaram-se a germinação, primeira contagem de germinação, comprimento e massa seca de plântula, além de análises bioquímicas do conteúdo de açúcares totais, aminoácidos totais e prolina. Os dados coletados foram submetidos à análise de variância (p ≤ 0,05) seguido do teste de Tukey e análise de regressão. O tratamento de sementes de cenoura com tiametoxam, no geral, influenciou positivamente a germinação das sementes das cultivares estudadas. No entanto, as dosagens de 0,4 e 0,8 mL de tiametoxam para cultivar Tropical não houve influência positivamente o desenvolvimento de plântulas. A dose de 1,2 mL do bioativador, para a cultivar Alvorada, foi benéfico ao desenvolvimento de plântulas e acúmulo de metabólitos

Pre-germination treatments with plant growth regulators and bioactivators attenuate salt stress in melon: effects on germination and seedling development

The scarcity of surface water has led to the use of underground sources as an alternative for crop irrigation by farmers in semi-arid regions. However, these water sources generally have high salinity, which prevents agricultural production. The objective of this study was to determine the effects of pre-germination treatments with plant growth regulators and bioactivators on melon seeds to attenuate salt stress caused by irrigation water during germination and seedling development. Two trials were carried out separately with the hybrids, Goldex and Grand Prix. The design was completely randomized in a 4 × 3 factorial scheme (four seed treatments and three dilutions of irrigation water). Seeds were treated with salicylic acid and gibberellic acid and the insecticide, thiamethoxam, in addition to the control. Local supply water, artesian well groundwater, and dilution of these waters at a 1:1 ratio were employed for irrigation. Fourteen days after sowing, morphological and physiological analyses were performed, and the material was collected for biochemical determination. The use of saline well water affected the initial development of melon seedlings of the Goldex and Grand Prix hybrids. Pre-germination treatment of Goldex hybrid seeds with gibberellic acid was inefficient at mitigating salt stress. However, the effects of irrigation water salinity on Grand Prix melon seeds pretreated with salicylic acid and thiamethoxam were attenuated

Caracterization of seed germination of Zephyranthes sylvatica (Mart.) Baker (Amarilidacea)

Zephyranthes sylvatica is a beautiful lily, endemic from the Brazilian Caatinga. Although it has a great ornamental potential, little is known about this species, especially regarding its seeds germination process. Aiming to characterize the germination of Z. sylvatica seeds, we studied its imbibition curve, optimum temperature and substrate for germination and seedling emergence, osmotic and salt stress tolerance, as well as the tolerance to frosting/ defrosting, which indicates long term cryostorage potential. The germination of Z. sylvatica presents a triphasic model of imbibition, in which the primary root protrusion occurs after 72 hours of imbibition. The ideal conditions for evaluating seed germination of Z. sylvatica is 25 ºC, in paper rolls. These seeds are highly tolerant to osmotic stress, but not to salt stress. Z. sylvatica seeds can be cryopreservated without loss of germination and seed vigor