March 2009

Plant growth, metabolism and adaptation in relation to stress conditions XXIII. Salinity-biofertility interactive effects on growth, carbohydrates and photosynthetic efficiency of lactuca sativa

M. N. A. Hasaneen, M. E. Younis and S. M. N. Tourky

Abstract

The interactive effects of different levels of NaCl and two biofertilizers on certain aspects of growth and metabolism of lettuce plants were investigated. The addition of a recommended dose of phosphorein biofertilizer to salinized soil, induced significant increases in all growth and reproductive parameters determined in growing lettuce plants. On the other hand, fertigation of such sodic salty soil with a recommended dose of nitrobein biofertilizer, induced slight decreases in the growth and reproductive parameters. The carbohydrate as well as pigment components and the activity of PS II of the salinized lettuce plants fertigated with phosphorein, were increased throughout the three successive growth stages, above the control levels. On the other hand, nitrobein did slight changes in all the metabolites determined, throughout the entire period of the experiment. The results are discussed in relation to applicability of the biofertilizers to sodic salty soil.

Keywords: lettuce; salinity; biofertilizers; growth; carbohydrates; pigments; PS II activity.

Page 60-69 (PDF Full Text)

Genetic behavior and impact of various quantitative traits on oil contents in sunflower under waters stress conditions at productive phase

Mudassar Iqbal, M. Amjad Ali, Amjad Abbas, M. Zulkiffal, M. Zeeshan and Hafeez A. Sadaqat,
Abstract

The research pertaining to the genetic behavior and impact of various quantitative traits on oil contents in sunflower under water stress conditions at reproductive stage in ten accessions (G-5 G-3, G-9, G-33, G-57, G-93, G-128, A-133, A-75 and HBRS-2) of sunflower was conducted following a triplicate randomized complete block design. The genotypes exhibited significant varietal differences among them for all the characters studied. Whorls per head (0.53) and number of leaves (0.66) displayed highest genotypic and phenotypic coefficients of variation respectively. Heritability in broad sense was the maximum for oil contents (0.715±0.346) followed by achene yield per plant (0.499±0.289) with considerable values of genetic advances indicating the involvement of some additive effects in the inheritance of these traits. Total leaf area exhibited the uppermost value of genetic advance (77.088) with moderate heritability (45±2.76). Plant height showed positive and significant genotypic association with leaf area and achene yield. Similarly number of leaves displayed positive and significant correlation (r=0.727*) with total leaf area and oil contents at genotypic level. The parameters stem diameter, head diameter, whorls per head and fertile whorls per head demonstrated positive and significant genotypic and phenotypic relationship between them. The number of whorls per head disclosed positive genetic association (r=0.625*) with oil contents while oil contents were negative associated with hundred achene weight (r= -0.768*). Path analysis based on oil content as dependent variable revealed that number of leaves, total leaf area, stem diameter and achene yield exerted positive direct effects on the oil contents being stem diameter at the top of the list. Stem diameter exposed the highest indirect positive effects on oil contents through head diameter, whorls per head and fertile whorls per head. These studies revealed that the selection of traits positively associated with oil contents and having positive direct and indirect effects on it could be an efficient selection criteria for oil contents in sunflower.

Keywords: Sunflower; water stress; genetic parameters; correlation; path analysis

Page 70-77 (PDF Full Text)

The effect of low temperature on metabolism of membrane lipids in plants and associated gene expression

Cosmin Badea and Saikat Kumar Basu
Abstract
Lipid metabolism plays an important role in the mechanism of frost or cold-tolerance in plants. Plant membrane lipids have the tendency to change from gel to liquid-crystalline phase in response to low temperature stress. This process is due to the increased level of lipid desaturation. The responsible components of this process are, among others, the fatty acid desaturases. Controlling the activity of these enzymes affects the amount of polyunsaturated fatty acids on the glycerol backbone and eventually controls the plants sensitivity to low temperature stress. These metabolic processes trigger a series of changes at the transcriptional level, causing differential expression in genes. Numerous approaches towards this process from chemical to the advanced mass spectrometry were taken during the past decades and several of them will be discussed in this minireview. Metabolomics and transcriptomics seem to be the keys towards describing these complex mechanisms and providing the necessary understanding of lipid metabolic response to low temperature stress.

Keywords: Lipid metabolism; desaturase enzymes; desaturation; gene expression.

Page 78-84 (PDF Full Text)

Exogenous calcium alters pigment composition, g-glutamyl kinase and proline oxidase activities in salt-stressed Withania somnifera

Cheruth Abdul Jaleel and M.M. Azooz

Abstract

In the present study effect of sodium chloride and calcium chloride on the proline metabolism of Withania somnifera plants was studied. The plants were treated with 100 mM NaCl, 5 mM CaCl₂, 100 mM NaCl with 5 mM CaCl₂ solutions. Ground water was used for irrigation to control plants. Plants were harvested randomly on 30and 50 days after sowing (DAS). NaCl and CaCl₂ stressed plants showed decreased chlorophyll ‘a’, ‘b’, total chlorophyll and carotenoid content and also proline oxidase activity and increased g-glutamyl kinase activity when compared to control. The NaCl with CaCl₂ treated plants increased chlorophyll ‘a’, ‘b’, total chlorophyll content and proline oxidase activity and decreased the g-glutamyl kinase activity in all parts of Withania somnifera when compared to NaCl treated plants.

Keywords: calcium chloride; pigments; proline metabolizing enzymes; sodium chloride; Withania somnifera.

Page 85-90 (PDF Full Text)

Genetic basis of some quantitative traits in upland cotton (Gossypium hirsutm L.)

Muhammad Amjad Ali, Amjad Abbas, Muhammad Younas, Tariq Manzoor Khan
and Hafiz Mumtaz Hassan
Abstract

Five cotton cultivars were crossed in a complete diallel to study the inheritance of different polygenic traits. Genotypic differences were found to be significant (P<0.01) for all the characters. Adequacy tests disclosed that data of all the parameters were fully adequate for genetic analysis except bolls per plant, staple length, fibre strength, and fibre fineness, which was partially or not adequate. Additive component of genotypic variation (D) was significant and predominant for plant height, sympodia per plant, staple length and fibre strength, while dominance effects (H₁ and H₂) were main controlling factors for of monopodia per plant, number of bolls, lint percentage and seed cotton yield. More dominant genes were revealed in the parents for sympodia per plant, lint percentage and seed cotton yield. The values of heritability in narrow sense (h² n.s) and H₂/4H₁ demonstrated asymmetrical and unequal distribution of dominant genes in parents for all characters. Plant height, sympodia per plant, staple length and fibre strength exhibited high narrow sense heritability (h² n.s) due to the presence of additive gene action, whereas, monopodia per plant, number of bolls, lint percentage and seed cotton yield possessed low heritability. The genetic analysis suggested that plant height, sympodia per plant, staple length and fibre strength could be improved through sib family, pedigree and progeny selection, while exploitation of heterosis would be necessary to attain the genetic advancement in monopodia per plant, number of bolls, lint percentage and seed cotton yield.

Keywords: Additive-dominance model; components of variation; multigenic traits; Gossypium hirsutum

Page 91-97 (PDF Full Text)