In this work, clover was shown to respond to infection with Rhizobium leguminosarum bv. trifolii by producing reactive oxygen species. Superoxide radical and hydrogen peroxide were detected in infection threads and nodule primordia. The role of reactive oxygen species in clover-Rhizobium leguminosarum bv. trifolii symbiosis is discussed
In Solanum muricatum Aiton the development of cellular endosperm preceded the divisions of the zygote, and 5 days after pollination (dap) it consisted of several cells. The mature endosperm accumulated lipid and protein bodies. The separation and secretion zone on the embryo/endosperm interface was noted at 20 dap. The first division of the zygote occurred at 7 dap. The apical cell of the 2-celled proembryo produced the embryo proper, and the basal one gave rise to the suspensor, the central part of the root cap (columella) and the connecting layer of the embryonic root meristem. Four-celled proembryos were observed with the cells in linear arrangement at 8 dap. The first globular embryos were found at 16 dap, heart-stage embryos at 26 dap, torpedo-shaped embryos at 30 dap, and circinate embryos at 33 dap. After 56 dap no further changes were observed in the anatomical structure of the embryos. The testa of mature seeds was composed of the outer epidermis of the integument and a layer of obliterated parenchyma and endothelium.
This paper presents an analysis of the deficiencies and excesses of precipitation occurring during the growing season of winter rape and winter wheat in the context of rising air tem-peratures in Poland in 1971-2010. The greatest frequency of precipitation deficiencies in winter wheat production in April and July was registered in the north-eastern region of Poland (Olsztyn), in May in Poznan region and in June in Lublin region. Analysis of the levels of precipitation deficiencies and excesses during the spring-summer period of winter wheat and winter rape vegetation in 1971-2010 did not reveal significant trends of changes despite their spatial and time diversification. Total precipi-tation deficiencies during April-June period for winter rape was the highest in Poznan region (62 mm) and the lowest in Olsztyn region (39 mm). Winter wheat highest precipitation deficiency was observed in Poznan region (59 mm), while the lowest in Lublin (34 mm), and their amounts were lower compar-ing to winter rape. In winter rape production, precipitation excesses were less frequently observed than precipitation deficiencies. The greatest frequency of precipitation excesses for winter wheat was regis-tered in June in Olsztyn region. The greatest frequency of precipitation excesses in winter wheat pro-duction in June and July was registered in the regions of Olsztyn and Koszalin; in April and June in Lublin. Precipitation excess totals during the April-June period for winter rape were the highest in Lublin region (45 mm) and the lowest in Opole region (22 mm). Winter wheat excesses of precipitation during April-July period were bigger compared to winter rape; the greatest amounts were observed in Koszalin region (72mm), while the lowest in Lublin region (43 mm).
The article presents changes in thermal and precipitation conditions on Polish territory in the years 1971–2010 based on data from six meteorological stations (Koszalin, Olsztyn, Poznań, Lublin, Opole and Kraków). These data concern the monthly average air temperature, precipitation and the number of days with precipitation per month. Based on the analysis of changing trends in the study of meteorological elements, authors observed an increase in the mean annual air temperature of about 0.9°C over 10 years in all localities. In contrast, trends in the average monthly air temperatures were characterised by temporal and spatial variation. As a result of the increase in temperature, there was a change in the dates signifying the beginning and the end of the thermal periods: farming (OG), vegetation (OW), intensive vegetation (OIW) and maturation or thermal summers (OD/L). A tendency for these periods to start earlier was noted. Statistically signifi cant changes were found for the following periods: vegetation in Koszalin and Olsztyn, intensive vegetation at all stations and thermal summer only in Lublin. An increasingly later end to these periods was noted, and statistically signifi cant trends were found for the dates of the end of the following periods: maturation (thermal summer) at all stations except Opole, intensive vegetation in Poznań and Lublin and vegetation in Lublin and Opole. Seasonal and monthly precipitation totals in the years 1971–2010 were characterised by cyclicality. Signifi cant upward trends were found only in the case of monthly precipitation totals in August in Koszalin and the sum of precipitation in the cooler half of the year in Poznań. In contrast, there was more days with precipitation at all stations included in the study, but the statistical signifi cance of trends varied by location. Changes in thermal and precipitation conditions were accompanied by, among other factors, an increase in temperature, changes in the length of thermal periods and an increase in the frequency of rainfall. All of this is important information for the agricultural sector regarding changing crop conditions.
In Solanum muricatum Aiton the general flower structure was typical for Solanaceae. The anther wall comprised the epidermis, endothecium (restricted to the anther tip), 3-4 middle layers and secretory tapetum. Placentoids developed in the anther loculi. Tapetum degeneration was noted in buds with the corolla shorter than the calyx, while loculi were filled with microspore tetrads. At the next stage (corolla even with calyx) pollen grains were visible. The anthers opened with tip pores in the still-closed buds, and then at anthesis the stomium split along the hypodermal row of idioblasts. Inhibition of pollen tube growth in vivo was not observed under self- or cross-pollination.
The pistil of Solarium muricatum Aiton was composed of two carpels joined in a folded condition. The ovary was bilocular with a central placenta. The ovules were anatropous, unitegmic and tenuinucellar. The megaspore mother cell underwent meiosis in buds with the corolla shorter than the calyx, producing a linear tetrad. Embryo sac development was Polygonum-type. The embryo sacs were examined when corolla and calyx were the same length. In older ovules the hyposthase became visible. The cells in the center of the style formed a solid column of transmitting tissue. The papillate stigma was of the wet type. No anatomical or ultrastructural disturbances that would prevent seed set were observed in floral organ development.
In Lupinus luteus L., infection occurred via the curled root hair. Bradyrhizobia penetrated its cell wall, probably by localized digestion, and then multiplied into the interior of the root hair. Some rhizobia escaped the penetration site before the host cell built a new wall around it. Escaped bacteria passed the distance to the root hair cell base, probably in the space between the cell wall and plasma membrane. At the root hair cell base, cell wall penetration and matrix escape occurred again. After escaping the matrix, rhizobia were endocytotically directed to the interior of the dedifferentiated cortex cell, and during subsequent mitosis were segregated to the proximal derivative. Thus the cell became the bacteroid tissue initial. The bacteria that remained within the penetration site were immobilized here due to the production of cell wall around them. Internalized bacteria were initially associated with large numbers of vesicles bearing cell-wall-like matrix. In abortive primordia the bacteria penetrated the cell walls of competent cells, and associations of bacteria and cell-wall-like matrix surrounded with a membrane were produced. At this stage, symbiosis was arrested and the symbiosomes were degraded. Necrosis or lysis of some primordium cells was observed.