Beneficial effects of diatomite on the growth, the biochemical contents and polymorphic DNA in Lupinus albus plants grown under water stress

Abstract

Water is a major limiting factor in world agriculture and most crop plants are highly sensitive to even a mild water stress.The beneficial effects of diatomite is characterized by helping plants to overcome various biotic and abiotic stresses. Thus , this experiment was performed to study the ameliorative effect of diatomite (10g/kg) on each of growth, productivity, gas exchange , biochemical contents and polymorphic DNA of Lupinus albus L. plants grown in either well watered or two different soil water regimes (1 and 4 days withdrawal). Results showed that diatomite was able to alleviate the deteriorative effect of water stress on almost all measured criteria specially in plants grown under mild water stress (1+D).Soil fertilization by diatomite significantly increased all measured growth parameters expressed as shoot and root length, fresh and dry weight of shoot, root and pods and number of pods/plant above both untreated and water stress -free diatomite treated plants. Diatomite application improved the rate of photosynthesis, stomatal conductance, the contents of each of total soluble sugars (TSS), total soluble protein (TSP) , total phenols, auxins, gibberellins, cytokinins and ABA and the activity of four antioxidant enzymes namely, superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) and polyphenol oxidase (PPO) as compared to both control and stressed plants maintained at both levels of water regime. On the contrary, diatomite treatment markedly reduced transpiration rate and lipid peroxidation level to a minimum . Moreover, diatomite application either alone or combined with stress induced a distinctive protein electrophoratic band (92KD) which was absent in either the control or stressed plants. Three distinctive protein bands were also induced in stressed white lupin, two (65 and 25 KD) under one day drought and one (143K) under four day drought. Finally, diatomite induced several distinguished polymorphic DNA fragments using PCRRAPD analysis.