Photosynthesis and Stomatal-Conductance Responses of Johnsongrass (Sorghum halepense) to Water Stress

The influence of water stress on johnsongrass [Sorghum halepense(L.) Pers. ♯ SORHA] physiology was evaluated in a semiarid environment. Stomatal conductance of johnsongrass responded to more negative leaf water potential and increasing leaf temperature. The sensitivity of the leaf temperature effect was dependent on the soil water content. At low soil water content, conductance was limited by low water potential, and increasing leaf temperature had little effect. Conductance of CO2was related to net photosynthesis in a curvilinear manner, with conductance levels greater than 0.3 mol·m-2· s-1being in excess of that necessary for maximum photosynthesis. At both high conductance levels and low levels associated with increased water stress, intercellular CO2concentration increased, indicating nonstomatal limitations to photosynthesis. Decreased osmotic potential provided the highest correlation with the linear decline of photosynthetic rate as stress intensified. The expression of osmotic adjustment in johnsongrass is reported during grain filling. Plants in the milkdough stage of grain filling had approximately 0.3 MPa lower osmotic potential at any relative water content than those at anthesis.

Download Full-text

Growth and yield of rice cultivars under sprinkler irrigation in south-eastern Queensland. 3. Water extraction and plant water relations dash comparison with maize and grain sorghum

Australian Journal of Experimental Agriculture ◽

10.1071/ea9880249 ◽

1988 ◽

Vol 28 (2) ◽

pp. 249 ◽

Cited By ~ 14

Author(s):

S Fukai ◽

P Inthapan

Keyword(s):

Water Potential ◽

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Leaf Water Potential ◽

Osmotic Potential ◽

Root Length ◽

Dry Matter ◽

Root Length Density ◽

Leaf Water

Several physiological responses were compared, under irrigated and water-stressed conditions, in an attempt to explain the reasons for the greater reduction in dry matter production of rice compared with maize and sorghum in a water-limiting environment. Leaf water potential and leaf rolling were determined weekly, soil water profiles and root length density twice, and leaf osmotic potential once during a long dry period. Root length density of rice was at least as high as that of maize and sorghum in the top 0.6 m layer of soil in both the wet and dry trials. There was no difference in water extraction among the 3 species from this layer, while rice extracted less water than did the other species from below 0.6 m. High variability among replicates precluded any conclusion being drawn regarding root length in the deeper layer. Leaf water potential, measured in the early afternoon, was consistently lower in rice than in maize and sorghum, even when soil water content was high, indicating high internal resistance to the flow of water in the rice plants. The low leaf water potential in rice was accompanied by low osmotic potential, and this assisted in maintenance of turgor and dry matter growth when soil water content was relatively high. As soil water content decreased, however, leaf water potential became very low (less than - 2.5 MPa) and, for rice, leaves rolled tightly.

Download Full-text

Estimating Midday Leaf and Stem Water Potentials of Mature Pecan Trees from Soil Water Content and Climatic Parameters

HortScience ◽

10.21273/hortsci.47.7.907 ◽

2012 ◽

Vol 47 (7) ◽

pp. 907-916 ◽

Cited By ~ 9

Author(s):

Sanjit K. Deb ◽

Manoj K. Shukla ◽

John G. Mexal

Keyword(s):

Water Stress ◽

Water Potential ◽

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Soil Conditions ◽

Silty Clay ◽

Stem Water Potential ◽

Stem Water ◽

Two Parameter

Diurnal and temporal patterns of stem water potential (ψstem) and leaf water potential (ψleaf) were determined during June to Sept. 2010 and 2011 at lower (2.5 m tree height), mid- (4.6 m), and upper (7.6 m) canopy positions for two flood-irrigated, mature pecan [Carya illinoinensis (Wangenh.) K. Koch] orchards near Las Cruces, NM. Diurnal measurements of ψstem and ψleaf at three canopy heights were correlated under both dry and wet soil conditions. However, although soil water contents at Site 2 (silty clay loam texture) remained higher compared with Site 1 (sandy loam), ψstem and ψleaf values, particularly under dry soil conditions at Site 2, were consistently lower, showing the effect of clayey soil texture on pecan water stress. Diurnal patterns of ψstem and ψleaf indicated that measurements of ψstem and ψleaf should be made close to early afternoon (between 1400 and 1500 hr Mountain Standard Time) to evaluate mature pecan water stress, which also corresponded to maximum climatic stress conditions. Midday ψstem and ψleaf measured at three canopy heights over several irrigation cycles during the 2010 season were correlated with one another, midday soil water content at different depths, and atmospheric vapor pressure deficit (VPD). Multiple regression analysis [between midday ψstem or ψleaf and midday θavg (soil water content at 0 to 40 cm), air temperature (Tmd), and relative humidity (RHmd)] during the 2010 season revealed that two-parameter regression models [ψstem or ψleaf = f (midday θavg and Tmd)] were the most significant for the interpretation of midday ψstem or ψleaf at both sites. Using the two-parameter model, predictions of ψstem and ψleaf measured on the both shaded and sunlit sides of trees at three canopy heights for 2011 showed good agreement between measured and predicted ψstem and ψleaf (R2 ranged from 0.70 to 0.98). Two-parameter models derived in an earlier study generally underpredicted ψstem both in 2010 and 2011, which further supported the importance of the time of midday ψstem and ψleaf measurements suggested in this study.

Download Full-text

Leaf Gas Exchange and Water Relations of Lupins and Wheat. I. Shoot Responses to Soil Water Deficits

Functional Plant Biology ◽

10.1071/pp9890401 ◽

1989 ◽

Vol 16 (5) ◽

pp. 401 ◽

Cited By ~ 43

Author(s):

IE Henson ◽

CR Jensen ◽

NC Turner

Keyword(s):

Stomatal Conductance ◽

Water Potential ◽

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Leaf Water Potential ◽

Stomatal Closure ◽

Turgor Pressure ◽

Leaf Conductance ◽

Leaf Water

The effects of a progressive increase in soil water deficit on the leaf conductance and gas exchange of lupin (Lupinus cosentinii) and wheat (Triticum aestivum) were investigated in pot experiments in a temperature-regulated glasshouse, using a coarse, sandy soil characteristic of the Western Australian wheatbelt. Transpiration rates decreased rapidly in both species after water was withheld, mainly as a result of stomatal closure. Photosynthesis declined also, but to a lesser extent than conductance. Leaf extension in lupin was equally as sensitive to a decrease in leaf water potential and soil water potential as stomatal conductance. Stomatal closure served to maintain the water potential of lupin leaves to within 0.1 MPa of that of control (watered) plants as the soil water content decreased from 0.14 to 0.06 m3 m-3 and as the leaf conductance and the relative transpiration rate fell to less than 50% of control values. Maintenance of leaf water potential with decreasing soil water content and stomatal conductance was less evident in wheat. In both lupin and wheat, leaf conductance decreased linearly with soil water content and curvilinearly with bulk soil matric potential, indicating that water uptake was restricted at similar water contents and matric potentials in both species. Diurnal measurements on lupin indicated a substantial reduction in stomatal conductance after water was withheld, even when the leaf water potential at midday was reduced by only 0.1 MPa and no change could be detected in the bulk leaf turgor pressure. Conductance in lupin was reduced even though the soil matric potential decreased in only part of the rooting zone. This, together with the absence of any significant change in the leaf water potential, turgor pressure, or relative water content in lupin during the initial stages of stomatal closure, suggests that a soil or root factor initiates the reduction in leaf conductance - and hence regulates the shoot water status - in response to soil drying.

Download Full-text

Influence of Water Stress on Water Relations and Growth of a Tropical (C4) Grass, Panicum maximum var. trichoglume

Functional Plant Biology ◽

10.1071/pp9750581 ◽

1975 ◽

Vol 2 (4) ◽

pp. 581 ◽

Cited By ~ 7

Author(s):

TT Ng ◽

JR Wilson ◽

MM Ludlow

Keyword(s):

Growth Rate ◽

Water Stress ◽

Water Potential ◽

Water Content ◽

Soil Water ◽

Leaf Area ◽

Soil Water Content ◽

Relative Growth Rate ◽

Leaf Water ◽

Relative Growth

The effects of recurring cycles of short-term water stress on the water relations and growth of P. maximum var. trichoglume in pots of soil were investigated under controlled conditions. As soil water content decreased there was an increase in the resistance to water movement in the soil-plant system. Leaf stomatal resistance increased and concomitantly transpiration rate decreased when soil water content fell below 37 % (soil water potential of - 1 .0 bars) and leaf water potentials were less than - 6 bars. The leaf water potential at wilting (- 8 to - 10 bars) and the relation between leaf water potential and relative water content changed with leaf position on the tiller. The death of early-formed leaves on the plants was accelerated by water stress but, in contrast, the later-formed leaves died more rapidly in the control (unstressed) treatment so that finally the control plants had a higher proportion of dead leaves. Plant growth was reduced at soil water contents above the permanent wilting point. Reduction in net assimilation rate was the main determinant of lower relative growth rate of stressed plants over the initial cycles of stress but subsequently, as leaf area expansion was reduced, leaf area ratio also had a significant influence. Water stress influenced growth directly, and also indirectly via its effect on plant development (ontogeny). Two techniques were used to separate the direct from the indirect effects on relative growth rate Some published data which suggest a stimulation of growth rate after the relief of stress are re-interpreted and the effect is shown to be due mainly to differences in ontogeny between stressed and control treatments

Download Full-text

MITIGATION YIELD SCALED METHANE EMISSION FROM RICE GROWN IN WATER STRESS CONDITIONS WITH BIOCHAR AND SILICATE AMENDMENTS

International Journal of Big Data Mining for Global Warming ◽

10.1142/s2630534821500078 ◽

2021 ◽

Author(s):

MUHAMMAD ASLAM ALI ◽

SANJIT CHANDRA BARMAN ◽

MD. ASHRAFUL ISLAM KHAN ◽

MD. BADIUZZAMAN KHAN ◽

HAFSA JAHAN HIYA

Keyword(s):

Water Stress ◽

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Field Capacity ◽

Saturated Soil ◽

Rice Grain ◽

Standing Water ◽

Water Contents ◽

Soil Water Contents

Climate change and water scarcity may badly affect existing rice production system in Bangladesh. With a view to sustain rice productivity and mitigate yield scaled CH4 emission in the changing climatic conditions, a pot experiment was conducted under different soil water contents, biochar and silicate amendments with inorganic fertilization (NPKS). In this regard, 12 treatments combinations of biochar, silicate and NPKS fertilizer along with continuous standing water (CSW), soil saturation water content and field capacity (100% and 50%) moisture levels were arranged into rice planted potted soils. Gas samples were collected from rice planted pots through Closed Chamber technique and analyzed by Gas Chromatograph. This study revealed that seasonal CH4 emissions were suppressed through integrated biochar and silicate amendments with NPKS fertilizer (50–75% of the recommended doze), while increased rice yield significantly at different soil water contents. Biochar and silicate amendments with NPKS fertilizer (50% of the recommended doze) increased rice grain yield by 10.9%, 18.1%, 13.0% and 14.2%, while decreased seasonal CH4 emissions by 22.8%, 20.9%, 23.3% and 24.3% at continuous standing water level (CSW) (T9), at saturated soil water content (T10), at 100% field capacity soil water content (T11) and at 50% field capacity soil water content (T12), respectively. Soil porosity, soil redox status, SOC and free iron oxide contents were improved with biochar and silicate amendments. Furthermore, rice root oxidation activity (ROA) was found more dominant in water stress condition compared to flooded and saturated soil water contents, which ultimately reduced seasonal CH4 emissions as well as yield scaled CH4 emission. Conclusively, soil amendments with biochar and silicate fertilizer may be a rational practice to reduce the demand for inorganic fertilization and mitigate CH4 emissions during rice cultivation under water stress drought conditions.

Download Full-text

Effects of soil water depletion on the water relations in tropical kudzu

Pesquisa Agropecuária Brasileira ◽

10.1590/s0100-204x1999000700006 ◽

1999 ◽

Vol 34 (7) ◽

pp. 1151-1157

Author(s):

Adaucto Bellarmino de Pereira-Netto ◽

Antonio Celso Novaes de Magalhães ◽

Hilton Silveira Pinto

Keyword(s):

Water Stress ◽

Stomatal Conductance ◽

Water Content ◽

Soil Water ◽

Cover Crop ◽

Soil Water Depletion ◽

Pueraria Phaseoloides ◽

Water Depletion ◽

Relative Water ◽

Dry Soil

Tropical kudzu (Pueraria phaseoloides (Roxb.) Benth., Leguminosae: Faboideae) is native to the humid Southeastern Asia. Tropical kudzu has potential as a cover crop in regions subjected to dryness. The objective of this paper was to evaluate the effect of soil water depletion on leaflet relative water content (RWC), stomatal conductance (g) and temperature (T L) in tropical kudzu. RWC of waterstressed plants dropped from 96 to 78%, following a reduction in SWC from 0.25 to 0.17 g (H2O).g (dry soil)-1.Stomatal conductance of stressed plants decreased from 221 to 98 mmol.m-2.s-1, following the reduction in soil water content (SWC). The day after re-irrigation, g of water stressed plants was 15% lower than g of unstressed plants. Differences in T L between waterstressed and unstressed plants (deltaT L) rose linearly from 0.1 to 2.2ºC following progressive water deficit. RWC and T L of waterstressed plants paralled RWC and T L of unstressed plants the day after reirrigation. The strong decrease in SWC found in this study only induced moderate water stress in tropical kudzu. In addition, tropical kudzu recover rapidly from the induced water stress after the re-irrigation.

Download Full-text