O crambe é uma leguminosa com alto potencial para produção de biodiesel, devido ao seu elevado teor de óleo nos grãos. Existe grande preocupação, quanto à manutenção da qualidade fisiológica da semente por tempo mais prolongado, por pequenos agricultores. Este trabalho objetivou avaliar o potencial fisiológico de sementes de crambe (Crambe abyssinica Hochst), cultivar FMS Brilhante, em função de diferentes tipos de embalagem e armazenamento. O trabalho foi desenvolvido no Laboratório de Análise de Sementes da Universidade Estadual de Mato Grosso do Sul, em Cassilândia (MS), entre 2010 e 2011. O delineamento experimental utilizado foi o inteiramente casualizado, em esquema fatorial 4x4, sendo constituído pela combinação de tipos de embalagem (testemunha, metálica, garrafa plástica tipo PET e caixa de isopor) e tempos de armazenamento (zero, três, seis e nove meses), com quatro repetições. A embalagem metálica proporcionou melhor preservação da qualidade fisiológica de sementes de crambe, enquanto, para o aumento do tempo de armazenamento, este efeito foi negativo.

A Revista Ciência Agronômica é voltada para estudos relacionados com as Ciências Rurais e Recursos Naturais

Abiotic stress directly influences seed performance, so poor-vigor seeds under adverse conditions tend to show lower germination speed and rate. By controlling the hydration level of seeds (i.e., priming) with the addition of chemical agents, it is possible to elicit the maximum physiological potential of seeds, even under stress conditions. This study aimed to evaluate the priming effect of different chemical agents on the physiological potential of maize seeds under abiotic stress (polyethylene glycol induced water stress, hypoxia, low temperature and salt stress after controlled deterioration). The experimental design was completely randomized, in a 5 x 2 factorial scheme, consisting of different chemical agents used to hydrate the seeds [control without priming; control primed with water; calcium nitrate (0.2 %); amino acid L-phenylalanine (0.05 %); amino acid L-phenylalanine (0.5 %) + calcium nitrate (0.2 %)] and 2 seed lots, with four replicates. Priming with calcium nitrate lead to a greater germination and higher emergence rate of the seedlings under suboptimal temperature conditions, and seeds that underwent controlled deterioration showed greater germination levels with the use of calcium nitrate + phenylalanine in the priming process, regardless of the lot used. In general, seed priming allowed a greater expression of seed vigor, even though an interaction with lots was observed in some variables.

Seed priming is a practice for improving the expression of seed physiological potential. Such technique consists of synchronizing and reducing the time of seed germination by controlled hydration. The aim of this study was to evaluate the effect of seed-priming with different sugar sources and concentrations on the physiological quality Urochloa brizantha seeds and initial seedling performance. Before treating, seeds were scarified chemically with concentrated sulphuric acid (H₂SO₄) for 5 minutes to overcome physical dormancy. The experimental design was completely randomized in a 3 x 6 factorial scheme consisting of priming using three sugar sources (glucose, sucrose, and maltose) and six concentrations (zero [water control], 2%, 5%, 10%, 15%, and 20%), with four replicates. The seeds were primed by direct immersion for 2 hours at 25 ºC and, after hydration, they were dried for moisture equilibrium recovery. Seed germination, vigor, viability, and initial seedling growth were evaluated. The results showed that glucose was the source able to promote beneficial effects on the germination of U. brizantha cv. MG-5 seeds. Moreover, the supply of glucose at the concentrations of 2 and 5% for physiological conditioning increased seedling dry phytomass.

This research evaluated protected environment and substrates for jatoba seedling. Two protected environments were used: (i) black shading screen on the sides and roof; and, (ii) black shading screen on the sides and thermal-reflective aluminized screen on the roof. In each environment the following substrates formulated with cattle manure (M) and vermiculite (V) were tested: 100% M; 90% M + 10% V; 80% M + 20% V; 70% M + 30% V; 60% M +40% V; 50% M + 50% V; 40% M +60% V; 30% M + 70% V; 20% M + 80% V; 10% M + 90%V. The environment protected with black shading screen was more favorable for the formation of jatoba seedlings, resulting in seedlings with higher shoot height and root collar diameter and, therefore, higher quality. Recommendation is to use substrates containing up to 30% of cattle manure to produce high quality jatoba seedlings.

The objective of the work was to evaluate the effects of nicotinamide application via seed immersion on seed physiological quality and initial growth characteristics. Two experiments were carried out, in the laboratory (seed physiological potential) and another in a randomized block design, in a greenhouse (initial growth). Treatments consisted of immersion of seeds in six solutions with different concentrations of nicotinamide (0, 100, 200, 300, 400, and 500 mg·L⁻¹). Characteristics related to primary root protrusion speed, average protrusion time, protrusion rate, and primary root length were evaluated under different temperature conditions (18°, 25°, and 35°C), and gas exchange, plant height, stalk diameter, number of leaves, aerial fresh weight, aerial dry weight, and root dry weight were evaluated. It was found that the use of nicotinamide, despite delaying the process of radicle protrusion, increases its development under stressful temperature conditions and results in an increase in gas exchange processes and gain in initial growth, mainly in the aerial part. Thus, it is concluded that the use of nicotinamide in maize seeds has the potential for use in stressful environments, as well as for obtaining greater initial growth, in which concentrations between 200 and 300 mg·L⁻¹ are suitable for the crop.