ABSTRACT Chromium is present in the tannery sludges worldwide making it a problem for agriculture. This study aimed to evaluate whether humus functions as a chromium stabilizing agent when using tannery sludge in the substrate of conilon coffee seedlings (Coffea canephora) and to determine what effects there are on leaf development and anatomy. Treatments consisted of a fixed dose of tannery sludge (30% of volume) on substrates of conilon coffee seedlings with different proportions of humus and subsoil (T-10, T-20, T-30, T-40% of humus). Information for the evaluation of leaf anatomy and seedling development was collected at 180 days after the planting of cuttings. From the phenological point of view, the treatments that best promoted seedling quality were T-30 and T-40. However, the greater the amount of humus in the substrate the greater the absorption of chromium by plants, which directly affected the organization of epidermal cells and leaf mesophyll. In addition, intense cytoplasmic degradation, ultrastructural changes in chloroplasts and mitochondria, and an increase in autophagic vacuoles were observed. We conclude that increasing the amount of humus in substrate with tannery sludge provides higher quality coffee seedlings, despite promoting greater absorption of chromium by plants and the consequent major intracellular disturbances.

Resumo Qualea é um gênero comumente encontrado em diferentes fisionomias do cerrado brasileiro, crescendo em ecossistemas abertos até áreas florestais fechadas, sujeitos à alta irradiância, incêndios, baixa disponibilidade de nutrientes e deficit hídrico sazonal. Comparam-se aqui, atributos estruturais foliares de Qualea grandiflora Mart., Qualea multiflora Mart., e Qualea parviflora Mart., em uma área de cerradão na transição entre os biomas Cerrado-Amazônia. Amostras foliares foram coletadas na Reserva Biológica Municipal Mário Viana, Nova Xavantina, Mato Grosso - Brasil, e processadas segundo as técnicas usuais para microscopia óptica. Cutícula espessa, cristas estomáticas, estômatos distribuídos entre as criptas estomáticas, densidade e distribuição dos tricomas tectores, hipoderme, mesofilo isobilateral com poucos espaços intercelulares, abundância de esclerênquima associado aos feixes vasculares e presença de extensões de bainha do feixe vascular são atributos anatômicos típicos de ambientes xerófilos. Encontraram-se diferenças estruturais qualitativas entre as espécies, com Qualea grandiflora apresentando estômatos com cristas distribuídos entre criptas estomáticas, e a presença de hipoderme em Qualea multiflora, e Qualea parviflora. Os resultados sugerem que as espécies são xeromórficas na região de transição Cerrado-Amazônia e que possuem atributos foliares adaptativos para lidar com as variações ambientais do seu habitat.

Abstract Qualea genus is commonly found in different phytophysiognomies of the Brazilian Cerrado, growing in open ecosystems to closed forest areas, under high irradiances, fires, low availability of nutrients and seasonal water deficit. We compared the leaf structural traits of Qualea grandiflora Mart., Qualea multiflora Mart., and Qualea parviflora Mart., in a cerradão area in the Cerrado-Amazonian forest transition. Leaf samples were collected at Mário Viana Municipal Biological Reserve, in Nova Xavantina, Mato Grosso state, Brasil, and processed according to the usual techniques for optical microscopy. Thick cuticle, stomatal ridges, stomata distributed between the stomatal crypts, density and distribution of tector trichomes, hypodermis, isobilateral mesophyll with few intercellular spaces, abundance of sclerenchyma associated to vascular bundles and the presence of vascular bundle sheath extensions are typical anatomic traits of xerophytic environments. We found qualitative structural differences among the species, with Qualea grandiflora having stomata with ridges distributed among stomatal crypts, and the presence of a hypodermis in Qualea multiflora, and Qualea parviflora. The results suggest that the species are xeromorphic in the region of Cerrado-Amazonian transition having leaf adaptive traits to deal with the environmental variations of their habitat.

ABSTRACT Secretory structures are formed by many types of plants and are present on numerous different organs. Among the many types of known secretory structures, colleters are predominant on plants of the Rubiaceae. One remarkable characteristic of secretory tissues is the export of exudates; however, the precise mechanism involved in this process is still unclear. To better understand the mechanisms of exudate externalization it is necessary to understand the ultrastructure and dynamics of the outer cell wall of the secretory structures during the secretory process, and so we investigated these aspects of the colleters of Bathysa nicholsonii. The outer cell wall (OCW) exhibits multiple layers: a basal polysaccharide rich layer; a cuticular membrane, which is subdivided into arborescent and reticulated layers; and a thin cuticle proper. The structural organization of the OCW is changed during secretion passage, which is mainly related to the development of a secretion accumulation site on the polysaccharide rich layer. Secretion dynamics is driven by the organization and disruption of the secretion accumulation site. The results show that the OCW of the colleters of B. nicholsonii is a dynamic structure with an active role in secretion externalization via constant structural reorganization directly related to secretion passage.