The morphology and ultrastructure of the nectaries of marrow (Cucurbita pepo L. convar. giromontiina)

Marta Dmitruk,Elżbieta Weryszko-Chmielewska

doi:10.5586/aa.2013.033

Abstract

The present study investigated the size and structure of the nectaries in flowers of marrow – <em>Cucurbita pepo </em>convar.<em> giromontiina </em>cv. ‘Weiser Busch’. The diameter and thickness of nectariferous layer were compared in female and male flowers of this taxon. The micromorphology as well as the anatomical and ultrastructural characters of the nectary from the female flower were observed using light, scanning and transmission electron microscopy. The density and size of stomata of the nectary epidermis from both types of flowers were examined using light microscopy. The nectaries in female flowers were found to have a larger size than in male flowers. The stomata occurring in the nectary epidermis of both types of flowers have a similar size and density. We observed that nectar was released onto the surface of the nectary not only via the stomata, but also through the walls of the epidermal cells. In TEM examination, large nuclei, different-shaped plastids, ER tubules, dictyosomes, and ribosomes were observed in the nectariferous tissue cells. A large number of mitochondria accompanying the plastids were found in the parenchyma cells of the nectary. The degradation of the nectary parenchyma cells in the flowers living for about 6 hours was asynchronous.

Highlights

In the climatic conditions of Lublin, flowering of marrow starts during the last 10-day period of June or the first 10-day period of July and most frequently lasts until the third 10-day period of September
The structure of nectaries sampled from the flowers after about 4 hours of blooming was examined in one-day flowers in which the physiological activity of the nectary glands was limited to several hours (Fig. 1 A)
The physiological and structural changes in the tissues of the nectary of marrow occurring during flowering take place asynchronously, since cells with well-preserved organelles and cells with advanced degradation of protoplasts are found close to one another

Summary

Introduction

Two species: C. pepo and C. maxima, which are valued for their dietetic fruits, are most frequently grown in the world and in Poland [1]. In the climatic conditions of Poland, squash belongs to plants that produce the largest amount of nectar per flower. According to Lipiński [5], under favourable conditions a female flower of C. pepo can produce up to 400 mg of nectar. Other studies reveal that on average 135.3 mg of nectar can be obtained from one female flower of marrow Large amounts of nectar in Cucurbita flowers are produced by one of the largest nectaries. A positive correlation has been found between the amount of nectar produced and nectary size in the case of flowers of Cucurbita and Cucumis [2,4,11]

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