engleski

Dimensions and areas of mesophyll cells during spruce needle development

Different structural changes are taking place during the development of spruce (Picea abies (L.) Karst.) needles resulting with formation of needle tissues: epidermal, hypodermal, mesophyll and vascular bundle. The aim of this study was to measure dimensions of mesophyll cells of spruce needles during development. Six developmental stages of spruce needles were sampled: vegetative buds, four stages of young needles, distinguished regarding to the needle length (stage I - 7 mm, stage II - 11 mm, stage III - 15 mm and stage IV - 19 mm) and previous-season needles. The dimensions and areas of mesophyll cells were measured on 3 μ m thick transversal sections of spruce needles and buds. Differences in structure and shape of cells composing the needle mesophyll were shown comparing different developmental stages. Mesophyll cells showed increase in width and length between each developmental step. The exceptions were shown between stages II and III, where change in width was not approved to be statistically significant, as well as between stage IV and previous-season needles, where the lack of significance was present concerning length and area. The most pronounced change happened during transition from vegetative buds to developmental stage I of young needles, while the slightest changes were expressed between developmental stage IV and previous-season needles. Obtained results pointed out that time rate of about two months was needed for needles development regarding to the mesophyll cells dimensions and areas.

development; spruce needles; dimensions; areas; mesophyll cells

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