NITROGEN ASSIMILATION, ROOT GROWTH AND WHOLE PLANT RESPONSES OF SOYBEAN TO ROOT TEMPERATURE, AND TO CARBON DIOXIDE AND LIGHT IN THE AERIAL ENVIRONMENT *

This paper discusses whole-plant responses to salinity in order to answer the question of what process limits growth of non-halophytes in saline soils. Leaf growth is more sensitive to salinity than root growth, so we focus on the process or processes that might limit leaf expansion. Effects of short-term exposure (days) are considered separately from long-term exposure (weeks to years). The answer in the short term is probably the water status of the root and we suggest that a message from the root is regulating leaf expansion. The answer to what limits growth in the long term may be the maximum salt concentration tolerated by the fully expanded leaves of the shoot; if the rate of leaf death approaches the rate of new leaf expansion, the photosynthetic area will eventually become too low to support continued growth.

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Photosynthetic Responses of Swiss Chard, Kale, and Spinach Cultivars to Irradiance and Carbon Dioxide Concentration

HortScience ◽

10.21273/hortsci11799-17 ◽

2017 ◽

Vol 52 (5) ◽

pp. 706-712 ◽

Cited By ~ 6

Author(s):

John Erwin ◽

Esther Gesick

Keyword(s):

Carbon Dioxide ◽

Dark Respiration ◽

Carbon Dioxide Concentration ◽

Controlled Environment ◽

Plant Responses ◽

Whole Plant ◽

Swiss Chard ◽

Spinacea Oleracea ◽

Photosynthetic Responses ◽

The Impact

The impact of irradiance (0–1200 μmol·m−2·s−1) and carbon dioxide concentration (CO2; 50–1200 ppm) on kale (Brassica oleracea and B. napus pabularia; three cultivars), Swiss chard (chard, Beta vulgaris; four cultivars), and spinach (Spinacea oleracea; three cultivars) photosynthetic rate (Pn; per area basis) was determined to facilitate maximizing yield in controlled environment production. Spinach, chard, and kale maximum Pn were 23.8, 20.3, and 18.2 μmol CO2·m−2·s−1 fixed, respectively, across varieties (400 ppm CO2). Spinach and kale had the highest and lowest light compensation points [LCPs (73 and 13 μmol·m−2·s−1, respectively)] across varieties. The light saturation points (LSPs) for chard and kale were similar at 884–978 μmol·m−2·s−1, but for spinach, the LSP was higher at 1238 μmol·m−2·s−1. Dark respiration was lowest on kale and highest on spinach (−0.83 and −5.00 μmol CO2·m−2·s−1, respectively). The spinach CO2 compensation point (CCP) was lower (56 ppm) than the chard or kale CCP (64–65 ppm). Among varieties, ‘Red Russian’ kale Pn saturated at the lowest CO2 concentration (858 ppm), and ‘Bright Lights’ chard saturated at the highest (1266 ppm; 300 μmol·m−2·s−1). Spinach Pn was more responsive to increasing irradiance than to CO2. Kale Pn was more responsive to increasing CO2 than to irradiance, and chard Pn was equally responsive to increasing CO2 or irradiance. Implications and limitations of this work when “upscaling” to whole-plant responses are discussed.

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Accumulation of starch in wheat grain under different shoot/root temperatures during maturation

Functional Plant Biology ◽

10.1071/pp01006 ◽

2002 ◽

Vol 29 (4) ◽

pp. 495 ◽

Cited By ~ 13

Author(s):

Mohammed Guedira ◽

Gary M. Paulsen

Keyword(s):

Grain Growth ◽

Dry Matter ◽

Triticum Aestivum L ◽

Soluble Starch ◽

Plant Responses ◽

Direct Effects ◽

Root Temperature ◽

N Accumulation ◽

Whole Plant ◽

The Impact

The impact of high temperatures on accumulation of starch in the grain of wheat (Triticum aestivum L.) is usually attributed to direct effects of the stress on the enzymes involved. However, roots are extremely sensitive to temperatures that can be as high as those experienced by the shoots, and their role in whole-plant responses should be considered. Wheat (cv. Len) was grown at 15/15, 30/15, 15/30, and 30/30˚C shoot/root temperatures during maturation, and accumulation of dry matter and N, contents of sucrose and starch, and activities of enzymes in the pathway of starch assimilation in the endosperm, were measured weekly. Dry matter and N accumulation were affected more by root than by shoot temperatures. High whole-plant temperatures (30/30˚C) accelerated linear grain growth but diminished the duration of assimilation, the contents of sucrose and starch, and the activities of the enzymes involved. The effects of high root temperature (15/30˚C) resembled those of high whole-plant temperature, whereas low root temperature (30/15˚C) tended to ameliorate them. Sucrose synthase and soluble starch synthase were affected more than the other enzymes by high shoot and/or root temperature. However, treatments that caused the lowest activities resulted in the fastest, but briefest, linear rates of grain growth. We concluded that shoots and roots interact in the response of wheat to high temperature, and that stress on both organs affects accumulation of starch in grain.

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SALINITY STRESS RESPONSES OF MINIATURE DWARF TOMATO IN A WHOLE PLANT MICROCULTURE EVALUATION SYSTEM

HortScience ◽

10.21273/hortsci.25.9.1149c ◽

1990 ◽

Vol 25 (9) ◽

pp. 1149c-1149

Author(s):

M. A. L. Smith ◽

S. L. Knight ◽

M. J. Bass

Keyword(s):

Root Growth ◽

Stress Responses ◽

Evaluation System ◽

Time Course ◽

Shoot Growth ◽

Root Growth Inhibition ◽

Plant Responses ◽

Tissue Quality ◽

Osmotic Concentration ◽

Whole Plant

A whole plant microculture (WPMC) screening system facilitated rapid, quantitative appraisal of salt stress effects on `Micro-Tom' miniature dwarf tomato. Axillary bud explants were micropropagated on a hormone-free control medium (conductivity = 3.3 dS m-1), gradually introduced to treatments with increasing NaCl or Na2SO4 concentrations via biweekly subculture to fresh media (7,6, 12.8, or 18 dS m-1), and monitored over a subsequent 5 week culture period. Non-intrusive video image analysis techniques were adapted to quantify morphometric (shoot growth rate, area, and length; root length and area) and photometric (ruler and tissue quality) plant responses. Shoot growth was only slightly inhibited at 7.6 and 12.8 dS m-1, but was severely stunted and distorted on high salt (18 dS m-1) media. Root growth inhibition (significantly shorter and thinner primary rants) was first evident at 12.8 dS m-1 after 3 weeks of treatment. At 18 dS m-1, conspicuous retardation of root growth relative to controls could be gauged after only one week. Shoot tip chlorosis was observed in the lowest salt-supplemented treatment after three to four weeks of culture, but overall shoot yellowing at the two highest conductivities was marked after only a few days. Chlorosis symptoms were not uniform within treatments. Cell osmotic concentration showed a linear increase with increasing medium salinity. The WPMC system expedited time course observations of stress symptom development, paralleled stress response trends observed in solution culture tests, and provided an excellent vehicle to investigate plant adaptation to saline conditions.

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Ammonium application mitigates the effects of elevated carbon dioxide on the carbon/nitrogen balance of Phoebe bournei seedlings

Tree Physiology ◽

10.1093/treephys/tpab026 ◽

2021 ◽

Author(s):

Xiao Wang ◽

Xiaoli Wei ◽

Gaoyin Wu ◽

Shengqun Chen

Keyword(s):

Carbon Dioxide ◽

Enzyme Activities ◽

Atmospheric Carbon Dioxide ◽

Global Climate ◽

Co2 Concentration ◽

Rubisco Activase ◽

Plant Responses ◽

N Metabolism ◽

C And N ◽

Phoebe Bournei

Abstract The study of plant responses to increases in atmospheric carbon dioxide (CO2) concentration is crucial to understand and to predict the effect of future global climate change on plant adaptation and evolution. Increasing amount of nitrogen (N) can promote the positive effect of CO2, while how N forms would modify the degree of CO2 effect is rarely studied. The aim of this study was to determine whether the amount and form of nitrogen (N) could mitigate the effects of elevated CO2 (eCO2) on enzyme activities related to carbon (C) and N metabolism, the C/N ratio, and growth of Phoebe bournei (Hemsl.) Y.C. Yang. One-year-old P. bournei seedlings were grown in an open-top air chamber under either an ambient CO2 (aCO2) (350 ± 70 μmol•mol−1) or an eCO2 (700 ± 10 μmol•mol−1) concentration and cultivated in soil treated with either moderate (0.8 g per seedling) or high applications (1.2 g per seedling) of nitrate or ammonium. In seedlings treated with a moderate level of nitrate, the activities of key enzymes involved in C and N metabolism (i.e., Rubisco, Rubisco activase and glutamine synthetase) were lower under eCO2 than under aCO2. By contrast, key enzyme activities (except GS) in seedlings treated with high nitrate or ammonium were not significantly different between aCO2 and eCO2 or higher under eCO2 than under aCO2. The C/N ratio of seedlings treated with moderate or high nitrate under eCO2was significantly changed compared with the seedlings grown under aCO2, whereas the C/N ratio of seedlings treated with ammonium was not significantly different between aCO2 and eCO2. Therefore, under eCO2, application of ammonium can be beneficial C and N metabolism and mitigate effects on the C/N ratio.

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Carbon dioxide and Plant Responses

Scientia Horticulturae ◽

10.1016/s0304-4238(00)00210-7 ◽

2000 ◽

Vol 86 (3) ◽

pp. 264-266

Author(s):

Christian Gary

Keyword(s):

Carbon Dioxide ◽

Plant Responses

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Effects of Temperature on Root Morphology and Ectendomycorrhizal Development in Pinusresinosa Ait.

Canadian Journal of Forest Research ◽

10.1139/x75-024 ◽

1975 ◽

Vol 5 (2) ◽

pp. 171-175 ◽

Cited By ~ 5

Author(s):

Hugh E. Wilcox ◽

Ruth Ganmore-Neumann

Keyword(s):

Root Growth ◽

Root System ◽

Root Morphology ◽

Root Systems ◽

Second Order ◽

Root Temperature ◽

First Order ◽

Effects Of Temperature

Seedlings of Pinusresinosa were grown at root temperatures of 16, 21 and 27 °C, both aseptically and after inoculation with the ectendomycorrhizal fungus BDG-58. Growth after 3 months was significantly influenced by the presence of the fungus at all 3 temperatures. The influence of the fungus on root growth was obscured by the effects of root temperature on morphology. The root system at 16 and at 21 °C possessed many first-order laterals with numerous, well developed second-order branches, but those at 27 °C had only a few, relatively long, unbranched first-order laterals. Although the root systems of infected seedlings were larger, the fungus increased root growth in the same pattern as determined by the temperature.

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A MYB-related Transcription Factor from Sheepgrass, LcMYB2, Promotes Seed Germination and Root Growth under Drought Stress

10.21203/rs.2.10859/v3 ◽

2019 ◽

Author(s):

Pincang Zhao ◽

Shenglin Hou ◽

xiufang guo ◽

Junting Jia ◽

Weiguang Yang ◽

...

Keyword(s):

Transcription Factor ◽

Drought Stress ◽

Seed Germination ◽

Osmotic Stress ◽

Root Growth ◽

Genetic Manipulation ◽

Marker Genes ◽

Plant Responses ◽

Adverse Conditions ◽

Related Transcription Factor

Abstract Background Drought is one of the most serious factors limiting plant growth and production. Sheepgrass can adapt well to various adverse conditions, including drought. However, during germination, sheepgrass young seedlings are sensitive to these adverse conditions. Therefore, the adaptability of seedlings is very important for plant survival, especially in plants that inhabit grasslands or the construction of artificial grassland. Results In this study, we found a sheepgrass MYB-related transcription factor, LcMYB2 that is up-regulated by drought stress and returns to a basal level after rewatering. The expression of LcMYB2 was mainly induced by osmotic stress and was localized to the nucleus. Furthermore, we demonstrate that LcMYB2 promoted seed germination and root growth under drought and ABA treatments. Additionally, we confirmed that LcMYB2 can regulate LcDREB2 expression in sheepgrass by binding to its promoter, and it activates the expression of the osmotic stress marker genes AtDREB2A, AtLEA14 and AtP5CS1 by directly binding to their promoters in transgenic Arabidopsis. Conclusions Based on these results, we propose that LcMYB2 improves plant drought stress tolerance by increasing the accumulation of osmoprotectants and promoting root growth. Therefore, LcMYB2 plays pivotal roles in plant responses to drought stress and is an important candidate for genetic manipulation to create drought-resistant crops, especially during seed germination.

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