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Desiccation in green algae: mechanisms and aquisition of tolerance
Belza, Václav Cedrik ; Pichrtová, Martina (advisor) ; Němcová, Yvonne (referee)
This thesis summarizes the current knowledge of the mechanisms that allow green algae to tolerate even severe desiccation. It provides a comprehensive overview, ranging from the definition of desiccation stress and its impacts on algal cells, through mechanisms that algae employ in defense, to the evolutionary background as well as a synthesis of recent research on the acquisition of desiccation tolerance and factors conditioning it. The first chapter defines the desiccation stress itself and breaks down the processes by which it can damage algal cells, including both morphological and physiological effects. The second chapter discusses diverse mechanisms involved in protection against desiccation. From mechanisms aimed at prevention of water loss (e.g. mucilage production or modification of cell wall permeability), through mechanisms that cause desiccation tolerance (e.g. accumulation of antioxidants, stabilization of proteins and phospholipids etc.), to the formation of resilient life stages. The third chapter is devoted to the evolutionary-historical background behind the emergence of desiccation tolerance per se and overview in which algal groups it is observable today. The last section is a synthesis of modern knowledge regarding acquisition of desiccation tolerance during algal life and...
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Influence of term of winter rapeseed (Brassica napus) desiccation on yield and seed quality
Rajtmajer, Stanislav ; Bečka, David (advisor) ; Petr, Petr (referee)
Rapeseed is the world's third most important oil plant (the second seminal). It is the most cultivation and most important oil plant in Czech Republic. Winter rapeseed reaches about 85% of the harvest area of oilseeds in the country. The desiccation of oilseed crop is sphere of agricultural engineering, which is still worth discussing. The main problems are how to use the product, what dose and which dates to choose to desiccate. The results of this thesis could help to partially clarify this complex issue.
The aim of the thesis is to observe the effect of different terms oilseed rape desiccation by glyphosate on yield and seed quality.
Small-plot experiments to investigate the influence of the term desiccation of winter rapeseed were established in the years 2013/2014 and 2014/2015 on the lands of the experimental station of the Czech Agricultural University, Faculty of Agronomy Food and Natural Resources at the Červený Újezd.
In the first experimental year 2013/2014 was founded five variants in three replications (including undesiccated control). In the year 2014/2015 was founded seven variants in four replicates (including undesiccated controls). In the first experimental year was the first term desiccation 16. 6. 2014, the second year 8. 6. 2015. Subsequent periods of desiccation were a week apart.
The variety of winter rapeseed used for the experiments was a hybrid variety Rohan. The desiccating agent was used Dominator active substance glyphosate. The dose of
4 l / ha + 200 l H2O.
For all samples, both experimental, years yield was determined, the weight of a thousand seeds and oiliness. For desiccated variants were carried out pre-harvest analysis for the determination of solids in pods. Further, all harvested samples taken for laboratory germination test (Determination of germination) ISTA according to the methodology. The results of the experiment sprouting were statistically analyzed using ANOVA analysis of variance. Differences between mean values were evaluated by Tukey test, the computer program SAS at a significance level of p = 0.05.
Effect of desiccation term influences of winter oilseed rape seed quality in terms of weight and thousands of seeds in terms of oil content. Too early desiccation (46 to 39 days before harvest) HTS reduced by 7-17% and the oil content of 2-4% of the overall average. Oiliness of the observed characters minimum interference term desiccation. Desiccation in the optimum date (17 days before harvest) increased oiliness of 1-6%.
Influence term desiccation oilseed rape also greatly influences seed yield.
Too early desiccation (46 to 39 days before harvest) reduced the yield by 11-14%. Undesiccated control in both years achieved the highest yields, increase yield by 5-12%. Desiccation in the optimum date (17 days before harvest) increased the yield of attempts by 5-6%.
The term desiccation of winter rapeseed, also significantly affects the vitality of seeds, where very reduces energy germinating seedlings in the first days. The term desiccation, however, does not affect overall seed germination. Too early desiccation (46 to 39 days before harvest) EK2 decreased by 12-40%, EK3 decreased by 4-24%, 3-4% EK4 and extended MGT of 7-15%. In the first experimental year was the most vital option undesiccated control (EK2 = 50.4% = 91.3% EK3, EK4 = 97.9%). In the second experimental year was the most vital seeds of the optimal term desiccation, (Sixth term, 17 days before harvest) = 68.9% EK2, EK3 = 98.2%, EK4 = 100%. Seed samples of 2014/15 had a higher overall vitality of seeds, than samples from 2013/14, the overall vitality is probably worse given year old and transsilaged seed.
The results of the two-year experiment that term desiccation affects the quality of seeds, the yield of seeds and vitality of seeds. Pre-analysis was determined optimum solids content in siliques desiccated samples to values of 40-50%. Like most technology seems to desiccation in the optimum date (17 days before harvest) and agro technology without desiccated vegetation. As the least appropriate technology seems very early desiccation (46 to 30 days before harvest).
The first scientific hypothesis: Premature desiccation reduces seed yield, oil content and HTS. Yes, the hypothesis was confirmed.
The second scientific hypothesis: Desiccation made in the correct term do not affect the quality of the seeds (oiliness and HTS). Yes, the hypothesis was confirmed.
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Effect of harvest interval from the end of the vegetation potato on the occurrance Rhizoctonia cancer
ZENÁHLÍK, David
The thesis on the topic of the influence of the time period distance of the harvest from the end of the vegetation on the occurrence of "potato fenkines on the bulbs." There were 11 varieties of the potatoes chosen for the observation. Their vegetation was terminated by the desication resource called Reglone. From the end of the terminated vegetation during 10 days until the harvest there were 4 samples taken and they were evaluated on the occurrence and it's percentage of the "potato flakiness on the bulbs" in accordance with the scale of Wenzel and Demel (1976). There were there varietes selected for the evaluation; Flavia (VR), Riviera (VR), Rosara (VR), Merida (R), Adéla (R), the Baccara (R), Marabel (R), Ditta (PR), Laura (PR), Maréna (PP) and Saturn (PP). The achieved results of the "potato flakiness" weere evalunted statistically. The aim of the evlution of the ("potato flakiness on their bulls") Rhizoctonia solani. The term of the vegetation termination depends on the grover and must be in written documentation. The harvest alome can follow after the the drawal period in the desiccation resource, which uswally 15 days. The results indicale that whem the harvest of the potatoes is made at the proper time after the termination of the vegetation, the potato bulls are withhout any largen percentage accurence of the "flakiness". The results achieved during the years 2012 and 2013 indicate that in early implementation off all the working operations important for the potato growing, which begin with sorting out, followed by plantig, care, chemical sprays, selection, parades, desiccation and the harvest, the "flakiness" dinďt exceed 5% of the occurence. Another results indicate that the taken bulls were undamaged and the difference of the occurrence of the "flakiness"on each sample appeared in a variety of ways. The years of abseving the experiment proved that there was an increase in the "flakiness" on the surface for a given time period.
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