Shoot

About: Shoot is a research topic. Over the lifetime, 32188 publications have been published within this topic receiving 693348 citations.

Growth and Salt Balance of the Mangroves Avicennia marina (Forsk.) Vierh. And Rhizophora stylosa Griff. In Relation to Salinity

Abstract: Seedlings of A. marina and R. stylosa were grown for 12 months in nutrient solutions containing 0, 25, 50, 75 and 100% seawater. Plants of both species grew poorly without sodium chloride in the culture medium. Growth was greatly stimulated in 25% seawater which, within the range of treatments used, was the optimum salinity for growth by both species. Dry matter production by R. stylosa fell sharply between 25 and 50% seawater, whereas A. marina displayed an extended growth response in up to 75% seawater. Plants of A. marina grown on solutions of increasing salinity accumulated increasing amounts of sodium and chloride in all tissues. As a result, all tissues had osmotic potentials that were considerably more negative than that of the solution on which they were grown. This implied that the reduction in growth displayed by plants of A. marina grown at high salinity was due to inhibition of growth by high concentrations of sodium and/or chloride, rather than to an effect of water stress. By contrast, the leaves and stem of R. stylosa contained relatively low concentrations of sodium and chloride, with the result that the osmotic potentials of these tissues were close to, or more positive than, that of the solution on which the plants were grown. This suggests that the poor shoot growth of this species at high salinities was due to water stress. The results of this study support the view that A. marina, which has salt-secreting glands in its leaves, is more salt-tolerant than R. stylosa, which does not possess salt-secreting glands.

Improved Salinity Tolerance of Arachis hypogaea (L.) by the Interaction of Halotolerant Plant-Growth-Promoting Rhizobacteria

Abstract: Salinity adversely affects plant growth and development. Halotolerant plant-growth-promoting rhizobacteria (PGPR) alleviate salt stress and help plants to maintain better growth. In the present study, six PGPR strains were analyzed for their involvement in salt-stress tolerance in Arachis hypogaea. Different growth parameters, electrolyte leakage, water content, biochemical properties, and ion content were analyzed in the PGPR-inoculated plants under 100 mM NaCl. Three bacterial strains, namely, Brachybacteriumsaurashtrense (JG-06), Brevibacteriumcasei (JG-08), and Haererohalobacter (JG-11), showed the best growth of A. hypogaea seedlings under salt stress. Plant length, shoot length, root length, shoot dry weight, root dry weight, and total biomass were significantly higher in inoculated plants compared to uninoculated plants. The PGPR-inoculated plants were quite healthy and hydrated, whereas the uninoculated plant leaves were desiccated in the presence of 100 mM NaCl. The percentage water content (PWC) in the shoots and roots was also significantly higher in inoculated plants compared to uninoculated plants. Proline content and soluble sugars were significantly low, whereas amino acids were higher than in uninoculated plants. The MDA content was higher in uninoculated plants than in inoculated plants at 100 mM NaCl. The inoculated plants also had a higher K+/Na+ ratio and higher Ca2+, phosphorus, and nitrogen content. The auxin concentration was higher in both shoot and root explants in the inoculated plants. Therefore, it could be predicted that all these parameters cumulatively improve plant growth under saline conditions in the presence of PGPR. This study shows that PGPR play an important role in inducing salinity tolerance in plants and can be used to grow salt-sensitive crops in saline areas.

Impact of two fluorescent pseudomonads and an arbuscular mycorrhizal fungus on tomato plant growth, root architecture and P acquisition

Abstract: The ability of fluorescent pseudomonads and arbuscular mycorrhizal fungi (AMF) to promote plant growth is well documented but knowledge of the impact of pseudomonad-mycorrhiza mixed inocula on root architecture is scanty. In the present work, growth and root architecture of tomato plants (Lycopersicon esculentum Mill. cv. Guadalete), inoculated or not with Pseudomonas fluorescens 92rk and P190r and/or the AMF Glomus mosseae BEG12, were evaluated by measuring shoot and root fresh weight and by analysing morphometric parameters of the root system. The influence of the microorganisms on phosphorus (P) acquisition was assayed as total P accumulated in leaves of plants inoculated or not with the three microorganisms. The two bacterial strains and the AMF, alone or in combination, promoted plant growth. P. fluorescens 92rk and G. mosseae BEG12 when co-inoculated had a synergistic effect on root fresh weight. Moreover, co-inoculation of the three microorganisms synergistically increased plant growth compared with singly inoculated plants. Both the fluorescent pseudomonads and the myco-symbiont, depending on the inoculum combination, strongly affected root architecture. P. fluorescens 92rk increased mycorrhizal colonization, suggesting that this strain is a mycorrhization helper bacterium. Finally, the bacterial strains and the AMF, alone or in combination, improved plant mineral nutrition by increasing leaf P content. These results support the potential use of fluorescent pseudomonads and AMF as mixed inoculants for tomato and suggest that improved tomato growth could be related to the increase in P acquisition.

Phosphorus Nutrition: Plant Growth in Response to Deficiency and Excess

Abstract: Phosphorus (P) is an essential element determining plants’ growth and productivity. Due to soil fixation of P, its availability in soil is rarely sufficient for optimum growth and development of plants. The uptake of P from soil followed by its long-distance transport and compartmentation in plants is outlined in this chapter. In addition, we briefly discuss the importance of P as a structural component of nucleic acids, sugars and lipids. Furthermore, the role of P in plant’s developmental processes at both cellular and whole plant level, viz. seed germination, seedling establishment, root, shoot, flower and seed development, photosynthesis, respiration and nitrogen fixation, has been discussed. Under P-deficient condition, plants undergo various morphological, physiological and biochemical adaptations, while P toxicity is rarely reported. We also summarize the antagonistic and synergistic interaction of P with other macro- and micronutrients.