V posledních 16 letech zažila Česká republika tři povodně, jejichž rozsah a následky nemají v moderních dějinách země obdoby. Zatímco moravská povodeň v roce 1997 se považovala za náhodnou událost, srpnová z roku 2002 v Čechách vedla ke zjištění, že náhody se mohou opakovat. Třetí povodeň v květnu 2013, kterou vzápětí vystřídalo období extrémního sucha, ukázala, že o náhody zřejmě nepůjde - že opakované extrémní fluktuace počasí musíme vnímat v jiných kategoriích než dosud a začít o nich uvažovat v širších souvislostech. and Josef Fanta.
Responses to drought were studied using two maize inbred lines (B76 and B106) and a commercial maize hybrid (Zea mays L. cv. Silver Queen) with differing resistance to abiotic stress. Maize seedlings were grown in pots in controlled environment chambers for 17 days and watering was withheld from one half the plants for an additional 11 days. On the final treatment date, leaf water potentials did not differ among genotypes and were -0.84 and -1.49 MPa in the water sufficient and insufficient treatments, respectively. Greater rates of CO2 assimilation were retained by the stress tolerant maize inbred line, B76, in comparison to the other two genotypes 11 days after watering was withheld. Rates of CO2 assimilation for all three genotypes were unaffected by decreasing the measurement O2 concentration from 21 to 2% (v/v). Activities of phosphoenolpyruvate carboxylase (PEPC), NADP-malic enzyme (NADP-ME), and NADP malate dehydrogenase were inhibited from 25 to 49% by the water deficiency treatment. Genotypic differences also were detected for the activities of NADP-ME and for PEPC. Changes of transcript abundance for the three C4 pathway enzymes also varied among watering treatments and genotypes. However, examples where transcripts decreased due to drought were associated with the two stress susceptible genotypes. The above results showed that enzymes in the C4 photosynthetic pathway were less inhibited by drought in stress tolerant compared to stress susceptible maize genotypes., R. Sicher, J. Bunce, J. Barnaby, B. Bailey., and Obsahuje bibliografii
Petr Petřík ; zpracováno z podkladů Josefa Fanty. and Sborník příspěvků ze seminářů Komise pro životní prostředí Akademie věd ČR konaných ve dnech 8. října 2013 a 5. června 2014