Germinação de sementes de três espécies do gênero Parkia submetidas a diferentes métodos de superação de dormência e temperatura

O trabalho teve como objetivo avaliar métodos de superação de dormência em diferentes temperaturas em sementes de Parkia pendula, Parkia platycephala e Parkia multijuga, visando a maximização e uniformização da germinação. As sementes de cada espécie passaram pelos seguintestratamentos: T1 – escarificação mecânica em esmeril elétrico; T2 - escarificação mecânica em esmeril elétrico seguido por imersão em água corrente por 24h; T3 – escarificação com ácido sulfúrico 98% por 10 min.; T4 – imersão em água a 80°C por 10 min.; T5- controle. As sementes de cada tratamento foram acondicionadas em germinadores do tipo B.O.D. em temperaturas de 25°C, 30°C e 25-30°C com fotoperíodo de 12 horas. Todas as espécies apresentaram interação entre os dois fatores estudados (superação de dormência e temperatura), ou seja, existe pelo menos uma combinação ideal entre esses fatores que otimiza a germinação e o aumento no IVG, com exceção da porcentagem de germinação para P. multijuga. Para superação da dormência de P. pendula e P. platycephala recomenda-se o T1 e para P. multijuga o T2. A temperatura de 30°C é recomendada para as três espécies

Effect of nickel seed treatment in soybeans

Micronutrients such as molybdenum (Mo), cobalt (Co), and nickel (Ni) have been shown to be necessary for maximizing the benefits of biological nitrogen fixation (BNF) in soybeans by mediating enzymatic processes of transforming gaseous nitrogen into mineral nitrogen. The objective of this literature review was to present a research based on a bibliographic review on the influence of nickel application on soybean seeds and its impact on increasing the productivity of this important legume in Brazilian agribusiness. A better understanding of the biochemical processes involved in biological nitrogen fixation in soybeans allowed the recognition of the relevance of nutrients such as Co, Mo, and Ni, especially in the constitution of enzymes such as urease and hydrogenase involved in this important symbiotic relationship between microorganisms and plants. As for nickel, a safe recommended dose for soybean seed treatment with this micronutrient has not yet been established, and relatively few studies have been conducted under Brazilian conditions. When nickel was applied to soybean seeds under various cultivation conditions, positive results were observed (greater nodulation, nodule weight, and enzymatic activity), higher nitrogen content in the plant and protein in the seeds, and higher productivity. Further research involving variables that directly affect nickel availability for soybeans, either through seed treatment or foliar application, still needs to be conducted before recommended dosages can be established

A probabilistic model for tropical tree seed desiccation tolerance and storage classification

Knowledge of seed desiccation tolerance is fundamental for conservation and use of forest species. The protocol used for classification of seed desiccation tolerance and storage is time consuming and many times limited by the lack of information about optimum conditions for seed germination and treatments to overcome seed dormancy. This study evaluated 66 Brazilian tree species aiming to correlate seed characteristics with desiccation tolerance. For this purpose, a model was established to explain the relationship of tegument/seed mass ratio (SCR), seed mass, and water content of embryo + endosperm with desiccation tolerance. The principal component analysis showed the establishment of two groups, indicating the interaction between desiccation tolerance and seed characteristics. Recalcitrant seeds are more often associated with the water content of embryo + endosperm and water content of tegument + endocarp, while orthodox seeds are more associated with SCR and number of seeds per kilogram. The classification found using the model proposed was significantly correlated with desiccation tolerance and storage, with 92% confidence for the analyzed species. Seeds morphological characteristics can be used for prediction of desiccation tolerance and storage behavior; however, the use of a model that combines more variables increases the chance of accurate classification