Susceptibility of alfalfa (Medicago saliva L. cv. Aragon) nodules and leaves to water stress has been investigated. Nodule acetylene reduction activity (ARA), leaf CO2 exchange rate (CER) as well as soluble protein, proline and total soluble sugar (TSS) contents were determined during drought. Water status was estimated as water potential (Ψw) and Relative water content (RWC) of the respective tissues. Maximum rates of ARA required higher Ψw than CER. Nodules had lower RWC for a given Ψw than leaves. Water stress reduced soluble protein content in both tissues; however, the decline in soluble protein content was detected at greater Ψw in nodules than in leaves. Proline and TSS increased in leaves and nodules, and again the threshold Ψw triggering such accumulation was higher in nodule tissues. Oior results suggest that alfalfa nodules are more susceptible to water shortage than leaves. Effects of accumulated TSS and proline upon leaf and nodule physiology are discussed in relation to protein stability (proline), pH control (proline) and osmotic adjustment (proiine and TSS). The TSS accumulation induced by water stress suggests that substrate shortage would not be the primary effect of drought on nodule activity.

Water stress induced changes in concentrations of proline and total soluble sugars in nodulated alfalfa (Medicago sativd) plants

Pea (Pisum sativum L. cv. Frilene) plants subjected to drought (leaf water potential of ≈-1.3 MPa) showed major reductions in photosynthesis (78‰), transpiration (83‰), and glycolate oxidase (EC 1.1.3.1) activity (44‰), and minor reductions (≈18‰) in the contents of chlorophyll a, carotenoids, and soluble protein. Water stress also led to pronounced decreases (72–85‰) in the activities of catalase (EC 1.11.1.6), dehydroascorbate reductase (EC 1.8.5.1), and glutathione reductase (EC 1.6.4.2), but resulted in the increase (32–42‰) of non-specific peroxidase (EC 1.11.1.7) and superoxide dismutase (EC 1.15.1.1). Ascorbate peroxidase (EC 1.11.1.11) and monodehydroascorbate reductase (EC 1.6.5.4) activities decreased only by 15‰ and the two enzymes acted in a cyclic manner to remove H2O2, which did not accumulate in stressed leaves. Drought had no effect on the levels of ascorbate and oxidized glutathione in leaves, but caused a 25‰ decrease in the content of reduced glutathione and a 67‰ increase in that of vitamin E. In leaves, average concentrations of catalytic Fe, i.e. Fe capable of catalyzing free-radical generation by redox cycling, were estimated as 0.7 to 7 μM (well-watered plants, depending on age) and 16 μM (water-stressed plants); those of catalytic Cu were ≈4.5 μM and 18 μM, respectively. Oxidation of lipids and proteins from leaves was enhanced two- to threefold under stress conditions and both processes were highly correlated. Fenton systems composed of the purported concentrations of ascorbate, H2O2, and catalytic metal ions in leaves produced hydroxyl radicals, peroxidized membrane lipids, and oxidized leaf proteins. It is proposed that augmented levels and decompartmentation of catalytic metals occurring during water stress are responsible for the oxidative damage observed in vivo.

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Drought induces oxidative stress in pea plants

Involvement of antioxidants and lipid peroxidation in the adaptation of two cool-season grasses to localized drought stress

To determine if antioxidant responses to drought differ between C3 and C4 plants, we grew Sorghum bicolor (C4 ) and Helianthus annuus (C3 ) under either watered or dry conditions in a growth chamber. Levels of leaf enzymatic antioxidants (ascorbate peroxidase, catalase, guaiacol peroxidase, dehydroascorbate reductase, monodehydroascorbate reductase, glutathione reductase and superoxide dismutase), nonenzymatic antioxidants (ascorbate, glutathione and carotenoids) and stress parameters (Chl and malondialdehyde [MDA]) were determined. Under watered and drought conditions, Chl contents and leaf relative water contents (RWC) were higher in sorghum than in sunflower; however, MDA levels were higher in sunflower than in sorghum. Under watered conditions, inherent levels of antioxidants were not consistently higher or lower in sorghum than in sunflower. In response to drought, levels of antioxidants, Chl and MDA showed increase, decrease or remained unchanged depending on crop, duration of drought and kind of antioxidants. Duration of drought was divided arbitrarily into three stages. At an early stage of drought (watering had stopped for 3-4 d) when soil water content (WC) and leaf RWC had decreased only in sunflower, drought generally did not affect levels of antioxidants and stress parameters. At a middle stage of drought (watering had stopped for 5-6 d) when soil WC had decreased for both sorghum and sunflower but leaf WC and RWC had decreased only in sunflower, drought changed levels of some antioxidants in sunflower and sorghum. At a late stage of drought (watering had stopped for 7-8 d) when soil WC, leaf WC and RWC had decreased in sorghum and sunflower, most parameters studied were affected by drought. Because of the differential effect of drought, levels of antioxidants were not consistently higher or lower in sorghum than in sunflower under drought. These results show that, under both drought and watered conditions, sorghum does not have consistently higher or lower antioxidant levels than sunflower, and that antioxidant responses to drought differ in C3 and C4 plants.

https://nph.onlinelibrary.wiley.com/doi/epdf/10.1111/j.1469-8137.1996.tb01856.x

Antioxidant responses to drought in sunflower and sorghum seedlings

1. The overall implications of biological stress.- 2. Oxidative stress.- 3. Salt stress.- 4. Chilling stress.- 5. Freezing stress.- 6. Desiccation.- 7. Water and drought stress.- 8. Heat stress.- 9. Anaerobic stress - flooding and ice-encasement.- 10. Environmental pollution stress.- Epilogue.

Stress and stress coping in cultivated plants

The cat tail (Typha elephantina), a non-food commercial crop grows as an emergent hydrophyte in tidal waterlogged areas. Its leaves are used for preparing mats and used as roof top and wall partition. Typha sp. has been found to be efficient accumulator of N from sediment under waterlogged condition. The N utilization mainly through nitrate reductase (NR) activity was studied in Typha with four levels of N fertilizers i.e. 0, 30 and 60 and 90 kg ha−1 applied at three stages of plant growth i.e. basal, 3 and 6 month after planting. In general, there was reduction in NR activity under waterlogged condition in Typha. But application of @ 90 kg ha−1 maintained high NR activity when it was applied as basal stage. Basal application of N was found better than its application at 3 or 6 month stage of crop growth. The higher leaf NR activity at 60 and 90 kg ha−1 N application level suggested better N utilization under waterlogged environment. The photosynthesis rate showed significant increase with higher N application concomitant with greater stomatal conductance (r = 0.84**; n = 12). There was significant increase in leaf yield when N was applied @ 90 kg ha−1 N level as basal dosage as compared to later stage (3 or 6 months) of crop growth. The highest fertilizer use efficiency (kg dry leaf kg−1 applied N) was also found at 90 kg N ha−1 as compared to 30 or 60 kg ha−1 N level, which corroborated superior N fertilizer utilization ability of Typha under waterlogged condition.

Effect of N application on its utilization and gaseous exchange in cat tail ( Typha elephantina ) under waterlogged condition

Seedlings of three different ages, ie 30, 45 and 60 days old of rice were grown at three different N levels, ie 0, 20 and 40 kg/ ha, for two years in waterlogged condition. Eventhough panicle number showed marginal increase, the panicle growth was superior in older seedlings more so at higher nitrogen level. The panicle length, spikelet number/panicle, panicle weight and number of filled grains/panicle showed significant improvement in older seedlings than younger seedlings of 30 days old. The effect was more pronounced at higher N level. The harvest index was also better in older seedlings at higher N level. In both the years 2007 and 2008 respectively the yield showed closer association with harvest index (r2 = 0.52, 0.76; n 27) than with total dry matter produced (r2 = 0.21, 0.56; n 27) suggesting importance of dry matter partitioning efficiency than total dry matter production efficiency for improvement of yield in waterlogged areas.

Growth and yield of over-aged rice (Oryza sativa) seedlings under different nitrogen levels in waterlogged situations

To discuss the intraoperative and postoperative complications of cranioplasty and management during a 7-year period. Retrospective study of 7-year period of 63 patients including both male and female. Highest experienced complications were seizures and dural tear, i.e., 6%, followed by EDH in 3% patients, hydrocephalus and pneumocephalus combined 3%, 1.6% CSF collection and flap necrosis each. All the complications were managed successfully. Complications of cranioplasty can be managed by following sound surgical principles. Serious complications like meningitis, air embolism and death are rare.

A Retrospective Study of Complications in Cranioplasty: 7-Year Period.

Delineation of Waterlogged areas using Spatial Techniques for Suitable Crop Management in Eastern India

Field experiments were conducted in WTCER research farm, Mendhasal and in the farmer's field at Bishwanathpur, Orissa, India, during two crop years to assess the performance of rice as influenced by drainage at different growth stages. In the first experiment, scented rice variety CR-689-113 was tested with drainage at different growth stages in the main plot and nitrogen levels in the sub plots. In the second experiment, rice variety Swarna was investigated and drainage at different growth stages was provided under the best nitrogen level. The results revealed that drainage at the tillering stage recorded significantly higher grain yield than drainage at all other crop stages. The grain yield of rice was found to be increased by 19–22% when drainage was provided at the tillering stage for an 8–10 day period relative to that of no drainage treatment. However, drainage at the panicle initiation stage recorded the lowest grain yield. Nitrogen at 60 kg ha−1 resulted in higher grain yield. Crop growth rate an...

S. Roy Chowdhury

Papers

Effect of N application on its utilization and gaseous exchange in cat tail ( Typha elephantina ) under waterlogged condition

Growth and yield of over-aged rice (Oryza sativa) seedlings under different nitrogen levels in waterlogged situations

A Retrospective Study of Complications in Cranioplasty: 7-Year Period.

Delineation of Waterlogged areas using Spatial Techniques for Suitable Crop Management in Eastern India

Studies on performance of rice as influenced by drainage in Eastern India