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Cristhian Camilo Chávez-Arias, Sandra Gómez-Caro, and Hermann Restrepo-Díaz

; Osorio-Guarín et al., 2016 ). Crops are currently facing waterlogging conditions (hypoxia) because of high rainfall, inefficient irrigation practices, and/or inadequate soil drainage, generating growth and yield limitations ( Herzog et al., 2016

Free access

Roberto López-Pozos, Gabino Alberto Martínez-Gutiérrez, Rafael Pérez-Pacheco, and Miguel Urrestarazu

A plant's roots must find oxygen in their immediate environment ( Drew, 1983 , 1992 , 1997 ). Early studies of oxygen content in nutrient solutions in water systems demonstrate that inadequate aeration may cause hypoxia in plant roots, and this

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Kwang-Hyun Baek and C.B. Rajashekar

Effects of hypoxia on germinating bean seeds (Phaseolus vulgaris cv. Tendergreen) were examined by imbibing them in water for various lengths of time. Hypocotyl elongation under hypoxic conditions and recovery from hypoxia in bean seeds were determined. Oxygen concentration in the water began to decrease sharply after 12 h of seed imbibition and had declined by more than 63% after 3 days of seed imbibition. When seeds were germinated on 0.8% agar after 24 h of imbibition, the hypocotyl elongation was reduced by about 70% compared to the seeds with no hypoxia, and longer imbibition resulted in poor or no germination. Exogenous hydrogen peroxide (20 mm) in water increased the oxygen concentration from 250 to 350 mm in the presence of seeds and was considerably higher after 3 days of seed imbibition than that in the control. Hypocotyl elongation occurred in seeds submerged in water containing hydrogen peroxide up to 72 h while none was observed in water. This was comparable to hypocotyl elongation under non-hypoxic conditions. Hypoxia in imbibing seeds was overcome by the high oxygen levels in the medium resulting from reaction of hydrogen peroxide with seed catalase and catalytic metal ions. Considerable catalase activity was detected in germinating seeds and the use of a catalase inhibitor, aminotriazole, suggests that the enzyme plays an important role in the release of oxygen into the medium. Of the catalytic metals, the seed content of iron was dominant and was about 6 folds higher than that of either copper or manganese.

Open access

Arye Gur and Shimon Meir

Abstract

Stored ‘Jonathan’ apple (Malus domestica Borkh) fruit from poorly aerated trickle-irrigated plots had a high incidence of “Jonathan breakdown” (starting as flesh browning beneath the peel) and, from sprinkle-irrigated plots, “Senescent breakdown” (starting from the core area). The flesh of such fruit was high in ethanol at picking time and in acetaldehyde after several months of storage. High ethanol levels in the fruit after 4 months of storage were related to a high ethylene production of the fruit. High soluble solid levels were characteristic of fruit prone to Jonathan breakdown but not to senescent breakdown. The acid content of the fruit flesh was directly correlated with the acetaldehyde content after several months of storage. The acetaldehyde content of the flesh of fruit from plots suffering from root hypoxia rose after 3 months of storage at 1°C. In contrast, the ethanol content of healthy fruit decreased gradually during storage. Fruit from plots suffering from root hypoxia, and particularly their peel, were low in Ca, Β, and Fe, but high in K. Low fruit Ca was related to high acid, acetaldehyde, and sorbitol levels. Fruit low in Ca softened rapidly in storage.

Free access

Nicole L. Waterland and Richard J. Gladon

subsequently with a resultant 100% stand establishment. Hypoxia (O 2 levels 5% or less) and anoxia (O 2 levels of 0%) suppress seedling and plant growth and inhibit metabolism in several species. Root growth of salt marsh plants at 2.5% to 10% O 2 was

Free access

Yanwen Gong and Theophanes Solomos

Previous research has shown that subjecting bananas to low O2 treatment during the climacteric rise decreases the rate of sugar accumulation but the fruits eventually ripen. In the present study we applied low O2 in fruits whose ripening had been initiated by exogenous C2H4 and in preclimacteric ones. In preclimacteric fruits low O2 suppressed the climacteric rise during the duration of the experiment (20 days). It completely inhibited the increase in sugars, invertase and sucrose phosphate synthase (SPS) activities while there was a sharp increase in sucrose synthase (SS). In control fruits the increase in sugar content coincides with a sharp increase in invertase, and SPS and a decline in SS. Hypoxia inhibited the increase in invertase and SPS while it induced an increase in SS. Nevertheless, the activities of invertase and SPS in the climacteric hypoxic fruits was higher than in hypoxic preclimacteric ones. The results, thus, indicate that the imposition of low O2 at the preclimacteric stage is much more efficient in delaying banana ripening than when it is applied after the initiation of ripening.

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Desmond G. Mortley, Conrad K. Bonsi, Walter A. Hill, Carlton E. Morris, Carol S. Williams, Ceyla F. Davis, John W. Williams, Lanfang H. Levine, Barbara V. Petersen, and Raymond M. Wheeler

it was suggested that this response was the result of root zone hypoxia caused by microgravity-induced changes in fluid and gas distribution ( Stout et al., 2001 ). Successful root growth is the all-important first step in the establishment of a

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Theophanes Solomos

In the past four years the effects of levels of O2 from 1 % to 100%1 on ripening of Gala apples were studied. It was observed that oxygen concentrations larger than 8% did not delay the onset of the climacteric rise in ethylene evolution and respiration, and had no effect on any parameters of ripening, such as texture, acidity and soluble solids. The timing of the onset in the rise of ethylene evolution differed with the year. Low O2 environments of 1-2% did not induce any rise in ethanol concentration. One hundred percent O2 was highly detrimental in that it induced visible symptoms akin to low O2 injury and enhanced the accumulation of ethanol. Hypoxic environments induced a novel 61 kd polypeptide whose quantity was inversely related to the levels of O2. The data also indicate that the effect of low O2 environments on respiration is a function of the physiological stage of the fruits.

Open access

Jonathan H. Crane and Frederick S. Davies

Abstract

The response of 2- to 3-year-old ‘Tifblue’ rabbiteye blueberry (Vaccinium ashei Reade) plants to periodic flooding of different durations and seasons was studied under field conditions in 1985 and 1986. Soil redox potentials (Eh) decreased to between 0 and −300 mV within 2 days of flooding and recovered to preflood levels (200 to 300 mV) within 8 to 10 days after flooding release. Plants survived 2-day (four periods) and 7-day (two periods) spring flooding treatments, whereas losses of 17% to 100% occurred after two 2- to 15-day summer flooding episodes. Most (83%) plants survived 106 to 117 days of spring flooding, while 33% and 0% survived 78 and 90 days of summer flooding, respectively. Generally, leaf area, percent fruit set, and yields decreased after two 7-day spring flooding periods, whereas the number of flower buds formed decreased by 38% to 70% with as little as two 2-day summer flooding periods. Stomatal conductance and transpiration decreased after the onset and increased after the release of the two 2- and 7-day summer flooding treatments, but remained low for the 15-day (two periods) and 78-day treatments. The effects of periodic flooding on plant survival, stomatal conductance, and the number of flower buds formed were similar to those found for continuously flooded plants in a previous study.

Free access

Charmara Illeperuma, Donald Schlimme, and Theophanes Solomos

Potato tubers (Solanum tuberosum `Russet Burbank') were stored at 1 °C in air for 28 days and then transferred to 10 °C in either air or 2.53 kPa O2. During cold storage there was an increase in sucrose, glucose, and fructose. The activities of extractable sucrose phosphate synthase (SPS) and invertase increased by 2.2- and 7.7-fold, respectively, during 28 days at 1 °C. The activity of sucrose synthase (SS) remained constant at 1 °C and was similar to that found in tubers kept continuously at 10 °C. With the transfer of tubers from 1 to 10 °C, there was an initial sharp rise in respiration which peaked at ≈7 days, followed by a gradual decline. Sucrose declined rapidly during reconditioning, while glucose and fructose declined more slowly. With the transfer of tubers from 1 to 10 °C, the activity of SS increased sharply after 7 days at 10 °C, to be followed by a decline to the levels found in control tubers. The activities of both extractable SPS and invertase decreased during reconditioning, reaching the values of the control tubers within ≈15 days. Low O2 inhibited the decrease in sugars and suppressed the rise in SS activity, but it did not alter the decrease in SPS and invertase. Western blot analysis showed that the amount of SPS protein remained unchanged at 1 and 10 °C. These results indicate that the activity of SPS is regulated by factors other than the amount of its protein. The activities of the above three enzymes showed no changes in tubers kept at 10 °C continuously. In control tubers SPS showed the highest activity, followed by SS and invertase.