Search results for "Stomata"
showing 10 items of 90 documents
Ni2+ toxicity in rice: effect on membrane functionality and plant water content.
2007
The heavy metal nickel is an essential mineral trace nutrient found at low concentrations in most natural soils. However, it may reach toxic levels in certain areas and affect a number of biochemical and physiological processes in plants. Wilting and leaf necrosis have been described as typical visible symptoms of Ni(2+) toxicity. The plasma membrane (PM) of root cells constitutes the first barrier for the entry of heavy metals but also a target of their toxic action. This work studies the relationship between disturbances of membrane functionality and the development of the typical symptoms of Ni(2+) toxicity. Rice plants (Oryza sativa L. cv. Bahia) grown in nutrient medium containing 0.5m…
Effects of long-term ozone exposure on citrus: Chlorophyll a fluorescence and gas exchange
2006
Three-years-old trees of Satsuma mandarin (Citrus unshiu [Mak.] Marc.) cv. Okitsu were exposed to O-3 fumigation during long term (one year) in open-top chambers. As a result of the treatment, chlorophyll a fluorescence and gas exchange parameters were modified with respect to trees growing in O-3-free conditions. Net photosynthetic rate and stomatal conductance decreased and intercellular CO2 concentration increased according to a reduction of the non-cyclic electron flow and a lower capacity to reduce the quinone pool. O-3 also reduced the development of non-photochemical quenching preventing the dissipation of excess excitation energy and, therefore, generated several alterations in phot…
Foliar characteristics, cambial activity and wood formation in Azadirachta indica A. Juss. as affected by coal–smoke pollution
2010
Abstract This study, aimed at elucidating changes in the foliar and cambial behavior in Azadirachta indica (Neem tree) due to coal-smoke pollution, has revealed inhibitory effects of pollution stress on leaf pigments concentrations, nitrate reductase activity and the contents of reducing sugars and total N content, whereas stimulatory effects were given on stomatal index and nitrate and sulphur contents. Under smoke effects, stomatal conductance was low, leading to a drop in the net photosynthetic rate and a rise in the internal CO2 concentration of leaf. Cambial reactivation in the stem was delayed at the polluted site. Although the total span of the cambial activity was reduced, greater a…
Influence of Ecklonia maxima Extracts on Growth, Yield, and Postharvest Quality of Hydroponic Leaf Lettuce
2021
Ecklonia maxima is a brown algae seaweed largely harvested over the last years and used to produce alginate, animal feed, fertilizers, and plant biostimulants. Their extracts are commercially available in various forms and have been applied to many crops for their growth-promoting effects which may vary according to the treated species and doses applied. The aim of the study was to characterize the effect of adding an Ecklonia maxima commercial extract (Basfoliar Kelp
Drought tolerance of clonal Malus determined from measurements of stomatal conductance and leaf water potential.
2003
We examined tolerance to soil drying in clonally propagated apple (Malus domestica Borkh.) rootstocks used to control shoot growth of grafted scions. We measured leaf conductance to water vapor (g(L)) and leaf water potential (Psi(L)) in a range of potted, greenhouse-grown rootstocks (M9, M26, M27, MM111, AR69-7, AR295-6, AR360-19, AR486-1 and AR628-2) as the water supply was gradually reduced. Irrespective of the amount of available water, rootstocks that promoted scion shoot growth (M26 and MM111) generally had higher g(L) and more negative Psi(L) than rootstocks that restricted scion shoot growth (M27 and M9). After about 37 days of reduced water supply, there were significant decreases …
Effects of partial rootzone drying and rootstock vigour on growth and fruit quality of 'Pink Lady' apple trees in Mediterranean environments
2008
We investigated the effects of partial rootzone drying (PRD) and rootstock vigour on water relations, and vegetative and productive performance of ‘Pink Lady’ apple (Malus domestica Borkh.) trees in central Sicily. In a first field trial, trees on MM.106 rootstock were subjected to: Conventional irrigation (CI), maintaining soil moisture above 80% of field capacity; PRD irrigation, where only one alternated side of the rootzone received 50% of the CI irrigation water; and continuous deficit irrigation (DI), where 50% of the CI water was equally applied to both sides of the rootzone. In a second trial, trees on M.9 or MM.106 were subjected to CI and PRD irrigation. PRD reduced stomatal condu…
Short-term response to waterlogging in Quercus petraea and Quercus robur: A study of the root hydraulic responses and the transcriptional pattern of …
2015
International audience; We characterized the short-term response to waterlogging in Quercus petraea (Matt.) Liebl. and Quercus robur L. as the initial response towards their known long-term differences in tolerance to waterlogging. One-month old seedlings were subjected to hypoxic stress and leaf gas exchange, shoot water potential (Psi(s)) and root hydraulic conductivity (Lp(r)) were measured. In parallel, the expression of nine aquaporins (AQPs) along the primary root was analysed by quantitative RT-PCR. Results showed a similar reduction in net assimilation (A) and stomatal conductance (g(s)) for the two species. Notably, the response of Lpr differed temporally between the two species. Q…
The effect of different vigour olive clones on growth, dry matter partitioning and gas exchange under water deficit
2012
Abstract In the last decade, high-density olive planting systems have been developed to facilitate less costly mechanical harvesting and pruning by using straddle harvesters. High-density orchards allow faster production since the first crop of fruit starts a few years after planting. In high-density orchards the control of tree size is essential. It is possible to control the vigour and size of the tree by selecting suitable cultivars, by choosing rootstocks capable of controlling scion vigour and, finally, by applying deficit irrigation to reduce plant vegetative growth. Knowledge of tree water requirements is needed for precise irrigation scheduling. In this study, the dwarfing capacity …
Diurnal Regulation of Leaf Water Status in High- and Low-Mannitol Olive Cultivars
2014
The role of mannitol and malic acid in the regulation of diurnal leaf water relations was investigated in ‘Biancolilla’ (high-mannitol) and ‘Cerasuola’ (low-mannitol) olive trees. Photosynthetic photon flux density (PPFD), vapor pressure deficit (VPD), stomatal conductance (gs), transpiration rate (T), relative water content (RWC), mannitol and malic acid were measured in ‘Biancolilla’ and ‘Cerasuola’ leaves during a dry and hot day of summer in Sicily. In general, leaves of ‘Biancolilla’ trees exhibited greater mannitol content, higher gs and T, but lower RWC than leaves of ‘Cerasuola’ trees. Differences in gs and T between the two cultivars were evident mainly in mid to late morning. ‘Bia…
Impact of Plasmopara viticola on starch metabolism and stomachal functions in grapevine leaves
2011
The grapevine downy mildew affects leaves and young berries and can affect the harvest quality and quantity. The causal agent is the obligate biotroph oomycete Plasmopara viticola that induces severe physiological alterations in infected leaves. One is the abnormal accumulation of starch in oil spots, the characteristic symptoms of the disease. Another is a deregulation of stomatal movements. Stomata, natural openings on the leaf surface allowing gas exchanges between the plant and the atmosphere, stay abnormally open during the night and do no longer close upon water stress or ABA treatment in infected leaves. This thesis is divided into two chapters that aim to i) explain the origin and m…