Estudos fenológicos podem fornecer informações que possibilitam compreender a dinâmica das plantas e sua relação com os fatores bióticos e abióticos do ambiente. Assim, buscando estudar as fases fenológicas do pinhão-manso, durante dois anos agrícolas foram avaliadas as seguintes cinco características agronômicas e variáveis climáticas como temperatura e precipitação. Os dados de cada variável, em cada ano e cada genótipo, foram submetidos a análise de variância (ANOVA) e as diferenças testadas a 5% de probabilidade pelo teste F. Além disso, analisou-se a correlação do comportamento vegetativo e reprodutivo de dois acessos de Jatropha (CNPAE-102 e CNPAE-169) em função do tempo decorrido após o início do ciclo fenológico com as variáveis climáticas por meio de correlação de Pearson. Verificou-se que: (i) a retomada do crescimento das plantas com a produção de novas ramificações e inflorescências de ambos os genótipos coincide com o início do período chuvoso; (ii) o florescimento pode estar relacionado a aumento da temperatura e da precipitação; (iii) número de inflorescências por plantas e número de flores femininas determinam o número de frutos verdes; (iv) variações ambientais são responsáveis pela delimitação das fenofases e (v) as respostas às mudanças fenológicas são genótipo dependentes.

Phenological studies can provide information that enables the understanding of the dynamics of plants and how these dynamics are related to the biotic and abiotic environment. In order to study the phenological phases of Jatropha during two agricultural years, agronomic and climatic variables, such as temperature and rainfall, were evaluated. Data for each variable in each year and each genotype were subjected to analysis of variance (ANOVA) and the differences were tested at 5% probability by F test. In addition, the correlation of growth behavior and reproductive development of two Jatropha accessions (CNPAE-102 and CNPAE-169) as a function of time elapsed after the start of the phenological cycle with climatic variables were analyzed through Pearson's correlation. It was found that: (i) the resuming of plant growth by producing new branches and flowers of both genotypes coincides with the start of the rainy season, (ii) the flowering may be related to the increase in temperature and rainfall; (iii) the number of inflorescences per plant and number of female flowers determine the number of green fruits, (iv) the environmental changes are responsible for the delimitation of phenophases; and finally that (v) the responses to phenological changes are genotype-dependent.

The supply of silicon (Si) to wheat plants may potentiate their resistance against infection by Bipolaris sorokiniana. Considering that there is no information regarding how Si affects the infectious process of this fungus on wheat leaves, this study intended to investigate, using light and scanning electron microscopy, the effects of Si supply on the infection process of B. sorokiniana on wheat leaves at tissue level. For that, leaf segments of -Si and +Si plants were prepared. The number of necrotic brown cells and the degree of browning of necrotic cells were determined for each infection site. As results, it was found that the number of brown epidermal cells and the frequency of infection sites showing browning were significantly lower on leaves of +Si plants. On the leaves of -Si plants, an intense dissolution of the wax layer also occurred and hyphae were found inside the disorganized epidermal cells. On leaves of +Si plants, degradation of the wax layer was observed only in areas close to conidia. Within 96 hours after inoculation, a dense network of hyphae had colonized the leaf surface of -Si plants, in striking contrast to +Si plants, for which only sparse hyphae were found.