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Start Over Coverage 157-160 Subject 2

1. Fertilization regimes under hot conditions alter photosynthetic response of bean plants

Creator:
Hassan, I. A., Abou Zeid, H. M., Taia, W., Haiba, N. S., Zahran, A., Badr, R. H., El Dakak, R. A., and Shalaby, E. A.
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
fotosyntéza, fazol obecný, photosynthesis, Phaseolus vulgaris, heat stress, nitrogen fertilization, photosynthetic performance, Phaseolus vulgaris L, French bean, 2, and 581
Language:
Multiple languages
Description:
We examined the effects of foliar application of various nitrogen (urea) concentrations on gas-exchange and chlorophyll (Chl) fluorescence characteristics in bean plants treated by heat stress (42/30°C, day/night temperatures). Heat stress caused reductions in contents of Chl a, Chl b, and in maximum photochemical efficiency of PSII by 13, 20, and 27%, respectively, regardless of the N treatment. However, N fertilization caused significant increases in these parameters, especially at higher N concentrations. The net photosynthetic rate and stomatal conductance were enhanced by 32, 60, and 69% and by 25, 88, and 100% due to addition of 5, 10, and 15 mM N, respectively. However, gas-exchange parameters were reduced by 24% due to heat stress. N fertilization alleviated adverse effects of heat stress., I. A. Hassan, H. M. Abou Zeid, W. Taia, N. S. Haiba, A. Zahran, R. H. Badr, R. A. El Dakak, E. A. Shalaby., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2. Photosynthesis, photosystem II efficiency, amino acid metabolism and ion distribution in rice (Oryza sativa L.) in response to alkaline stress

Creator:
Wu, Z.-H., Yang, C.-W., and Yang, M.-Y.
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
fotosyntéza, rýže, photosynthesis, rice, alkaline stress, photosystem II efficiency, amino acid metabolism, 2, and 581
Language:
Multiple languages
Description:
Alkalies are important agricultural contaminants complexly affecting plant metabolism. In this study, rice seedlings were subjected to alkaline stress (NaHCO3:Na2CO3 = 9:1; pH 8.9) for 30 days. The results showed that stress mightily reduced net photosynthetic rate (PN), but slightly decreased transpiration rate and stomatal conductance. This indicated that decline of PN might be a result of nonstomatal factors. Alkaline stress caused a large accumulation of Na+ in leaves up to toxic concentration, which possibly affected chloroplast ultrastructure and photosynthesis. We found that alkaline stress reduced chlorophyll fluorescence parameters, such as ratios of Fv′/Fm′, Fv/Fm, photosystem (PS) II efficiency, and electron transport rates in rice plants, i.e. it influenced the efficiencies of photon capture and electron transport by PSII. This might be a main reason for the decrease of PN under such conditions. Deficiency of minerals could be another reason for the decline of PN. Alkaline stress lowered contents of N, K, Cu, Zn, P, and Fe in rice plants. In addition, the stress strongly affected metabolism of amino acids. This might be caused by imbalance in carbon metabolism as a result of photosynthesis reduction., Z.-H. Wu, C.-W. Yang, M.-Y. Yang., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public