Showing 4 results for Chlorophyll
R Khavarinejad, R. Shekaste-Band, F. Najafi, Z Gharari,
Volume 13, Issue 1 (5-2013)
Abstract
In order to understand some physiological mechanism of chilling and cold sensitivity in plants we investigate the effects of chilling and cold stress on chlorophyll and proline content, lipid peroxidation and variable chlorophyll fluorescence (Fv/Fm) of Arabidopsis (thaliana L.) The four weeks-old plants (WT, and four chilling sensitive mutants [chs2-2], [chs2-1], [chs1-2] and [chs1-1]) were subjected to two different low temperature treatments (control (23̊ C), chilling (13̊ C) and cold (4̊ C)), for one week. Fv/Fm and chlorophyll content changed significantly in all mutants except in WT by chilling stress (13̊ C), compared with control and 4̊ C treatments. Two out of four mutants, chs1-1 and chs1-2, had lowest chlorophyll content and Fv/Fm value among the tested genotypes. The proline content increased in all mutant genotypes, as well as in WT by chilling stress and 4̊ C, compared with control. MDA content of shoots changed dramatically in all mutant genotypes except in WT by chilling stress, compared with control and 4̊ C treatments. Our findings showed that two mutants, chs1-1 and chs1-2, have had highest chilling sensitivity among the tested genotypes and had the highest proline and MDA contents. It is possible that some damages in photosynthetic systems and/or in proline metabolism via mutation cause these plants more sensitive to chilling and cold stress
Fatemeh Ghasemi, Reza Heidari, Rashid Jamei, Latifeh Poorakbar,
Volume 15, Issue 1 (4-2015)
Abstract
To assess nickel-induced toxicity in plants, Zea mays seeds after germination were cultured on hydroponic nutrient solution with nickel concentrations of 0, 50, 100 and 200 micro molar for a period of two weeks. Then its effect on the growth, Hill reaction and photosynthetic pigment's content were investigated. The fresh and dry weight of leaves and roots increased in 50 &muM nickel but decreased in 100 and 200 &muM. The decline in length of root and shoot were observed by increasing Ni concentration.According to results, root and shoot showed differential growth response to varried concentrations of nickel. Ni concentrations up to 100 &muM caused incrtease in the content of chlorophyll a, but it was decreased at 200 &muM Ni. No significant changes in chlorophyll b and carotinoids content observed. The rate of Hill reaction as an ability of chlorophyll a in the reaction center of PSII680 to split water, decreased by increasing Ni concentration.
Volume 18, Issue 56 (9-2006)
Abstract
Manganese (Mn) is a micronutrient that is essential for plant growth and develop-ment. Meanwhile, an excess amount of Mn is one of the most important growth limiting factors in acid soils. The present study was undertaken to identify the effects of excessive Mn on the physiological aspects of tea plant. To this end, 2-year old rooted cuttings of tea (Camellia sinensis L. assamica × sinensis) were grown in a modified Hoagland solution with pH=4.2 for 1 month with aeration in green house, with temperature of 27 ± 3 ˚C and photosynthetic photon flux of 101.5 µmol. m-2 s-1 (400-700 nm) at the plant level. After emergence of new, white roots with 5 to 10 cm in length, the plants were treated for 1 week with excessive Mn to a final concentration of 0.9 mM. After 1 week, the white roots were harvested and frozen in liquid N2 and kept at -80 ˚C until used for determination of PO activity, lignin and sugar as well as chlorophyll content. The activities of soluble peroxidase (SPO), covalently wall-bound peroxidase (CPO) and lignin content decreased by Mn treatment. On the other hand, the activities of ionically wall-bound peroxidase (IPO), sugar and chlorophyll contents increased by Mn treatment. These results suggest that excessive Mn may have beneficial effects on tea plant via lowering lignin content and increasing extensibility of the walls.
Volume 18, Issue 56 (9-2006)
Abstract
The mechanism of soybean(Glycine max L.cv.Gorgan 3) response to drought stress was evaluated. The plants were grown in pots under 23 ± 2°C temperature and 14000 lux light intensity and 14hr photoperiod. When first leaf appeard, three irrigation treatments occurred that consisted as one every day(control), once in three(mild stress) and in five days(sever stress).During 15 days the plants were irrigated an amount of 150 ml. The effect of irrigation treatment on the soluble sugar, total protein, proline, phenolic compound, chlorophyll content and nitrate reductase activity was studied.The results showed that in the root soluble sugar and proline content in mild and sever stress significantly increased while in the stem and the leaf these compound considarably increased under sever stress the total protein ,chlorophyll a,b and nitrate reductase activity in leaf especially decreased in sever stress. Also the decrease phenolic compound in leaf under this condition was significant
