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Gas exchange characteristics in relation to genotypes in spinach (Spinacia oleracea) under water stress
Helebrantová, Aneta ; Hnilička, František (advisor) ; Pazderů, Kateřina (referee)
The bachelors dissertation was compiled on theme of: Gas exchange characteristics in relation to genotypes in spinach (Spinacia oleracea) under water stress.
Spinach (Spinacia oleracea) is, similarly as the others leaf vegetables, difficult crop in terms of providing the sufficient level of moisture, therefore the attention is drawn to the varieties of spinach which are resistant to the water stress. Thus the target of cultivation is to find plant which will be resistance to influence of the water stress.
In climabox of department of botanics and physiology was founded experiment with three species of spinach: Misano F1, Monores a Matador. The temperature mode was set to 21 °C during the day and 17 °C during the night. The light mode was set to 16 hours of light and 8 hours of dark per day. Maximum light level in climabox was 800 micromole. The plants were cultivated in 4 recurrences, diagram of experiment is involving two variants: control and stress. The plants in control variant were cultivated in substrate, which was irrigated during the whole time of experiment by 250 ml of water. For the plants in stress variant the supply of water was suspended for 10 days and the substrate was naturally continuously dehydrating. After 10 days the water supply was restored (rehydration) for plants in stress variant, same as level of control variant. The observation was made for the speed of gas exchange (photosynthesis and transpiration) in two-day interval. The speed of gas exchange was measured on leaf area with infrared gasometric gas analyzer Lpro+ (ADC Bioscientific, Hodeson, UK). Measured was conducted in morning hours according. Based on the measured values of photosynthesis and transpiration we calculated water usage effectiveness (WUE).
Based on obtained results is evident that the highest average speed of photosynthesis in control variant was observed at variety of Monores (12,10 micromole CO2.m-2.s-1) and lowest at variety Misano (11,58 micromole CO2.m-2.s-1). The highest average speed of photosynthesis in stress variant was measured at variety of Matador (9,43 micromole CO2.m-2.s-1) and lowest at variety Monores (8,76 micromole CO2.m-2.s-1). There was observed decrease of photosynthesis for each of variety during the water stress.
The highest average values of transpiration were observed at variety Monores (1,97 mmol H2O.m-2.s-1), lowest at variety Matador (1,68 mmol H2O.m-2.s-1). Stressed variety Misano reached level of photosynthesis 1,82 mmol H2O.m-2.s-1. Control variety Matador reached speed of transpiration 1,54 mmol H2O.m-2.s-1 and variety Monores 1,85 mmol H2O.m-2.s-1.Variety Misano was on same level of control variant as stress variant.
The most sensitively reacted variety Monores, which usage of water was 4,43 (10-3). Variety Matador managed the stress well, the usage of water was 5,60 (10-3).
Obtained results confirmed hypothesis of genotype differences depending on water deficit, thus there are differences between gas exchange and WUE in control and stress plants.
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