NITROGENASE ACTIVITY, PHOTOSYNTHESIS AND TOTAL NONSTRUCTURAL CARBOHYDRATES IN COWPEA DURING AND AFTER DROUGHT STRESS

1990 ◽  
Vol 70 (4) ◽  
pp. 1005-1012 ◽  
Author(s):  
S. PARARAJASINGHAM ◽  
D. P. KNIEVEL
Keyword(s):  
Drought Stress ◽  
Stomatal Conductance ◽  
Vigna Unguiculata ◽  
Nitrogenase Activity ◽  
Net Photosynthesis ◽  
Dry Weight ◽  
Plant Parts ◽  
Total Nonstructural Carbohydrates ◽  
Nonstructural Carbohydrate ◽  
And Control

Greenhouse experiments were conducted to determine whether depressed nitrogenase activity (NA) of cowpea (Vigna unguiculata (L.) Walp.) nodules during drought stress is associated with altered carbohydrate supply to the nodules. Nitrogenase activity of the nodules, midday abaxial stomatal conductance, leaf net photosynthesis and mg total nonstructural carbohydrate (TNC) g−1 dry weight of several plant parts were measured in cowpea subjected to and recovering from drought stress periods of 0, 4 and 8 days. In addition, cowpea plants were shaded or partially defoliated (75% leaf removal) to limit carbohydrate supply to the nodules of well-watered plants. Stomatal conductance, leaf net photosynthesis and nodule NA declined 60, 62 and 90%, respectively, within 4 d of withholding water. After 8 d of drought stress, leaf net photosynthesis and nodule NA were near zero. Stomatal conductance and leaf net photosynthesis returned to the level of unstressed plants within 24 h following rewatering while recovery of NA was delayed. Shading and defoliation of cowpea plants under well watered conditions decreased NA 62 and 44%, respectively. TNC concentrations of leaves, petioles, stems, roots and nodules did not differ appreciably between drought stressed and control plants. In contrast, TNC concentrations of shoot plant parts from shaded or defoliated plants declined significantly compared to controls and nodule TNC concentrations declined in shaded plants. The decline in NA by cowpea nodules during drought stress did not appear to be directly associated with carbohydrate supply to the nodules, but rather the result of a new equilibrium attained with overall limited plant growth under the stress.Key words: Vigna unguiculata (L.) Walp., nitrogenase activity, drought stress recovery, assimilate stress, shading, defoliation, total nonstructural carbohydrate

NITROGENASE ACTIVITY OF COWPEA (Vigna unguiculata (L.) Walp.) DURING AND AFTER DROUGHT STRESS

1990 ◽  
Vol 70 (1) ◽  
pp. 163-171 ◽  
Author(s):  
S. PARARAJASINGHAM ◽  
D. P. KNIEVEL
Keyword(s):  
Drought Stress ◽  
Stomatal Conductance ◽  
Water Potential ◽  
Vigna Unguiculata ◽  
Nitrogenase Activity ◽  
Root Nodules ◽  
Experimental Period ◽  
Stress Recovery ◽  
Subsequent Recovery ◽  
Per Se

Greenhouse experiments were conducted with the objectives (1) to investigate the nitrogenase activity (NA) of cowpea (Vigna unguiculata (L.) Walp.) root nodules during the development of and subsequent recovery from drought stress and (2) to determine whether the changes in NA during and following drought stress are related to nodule water potential. Nitrogenase activity of root nodules decreased by more than 80% within 6–8 d of withholding water and recovered 1 or 2 d after watering. Nodule water potential declined significantly from approximately −0.2 MPa to −0.48 MPa with 8 d of stress and recovered to prestress levels within 24 h after watering. Midday abaxial stomatal conductance decreased significantly with stress but recovered within 24 h following watering. Midday leaf water potential did not change significantly during the experimental period. Nodule NA declined 2 d before that of nodule water potential in apparent response to declining soil water content. This response and the lag in the recovery of NA following drought stress after nodule water potential had returned to prestress levels support the hypothesis that nodule water potential per se is not the primary cause for the decline in NA of cowpea root nodules during drought stress.Key words: Vigna unguiculata (L.) Walp., nitrogenase activity, drought stress, recovery, cowpea

scholarly journals THE POTENTIAL USE OF Ca(NO3)2 TO IMPROVE SALINITY TOLERANCE IN DATE PALM (Phoenix dactylifera L.)

2021 ◽  
Vol 52 (2) ◽  
pp. 445-453
Author(s):  
Saleh M. Alturki
Keyword(s):  
Date Palm ◽  
Net Photosynthesis ◽  
Dry Weight ◽  
Phoenix Dactylifera ◽  
Inhibitory Effect ◽  
Plant Parts ◽  
Salinity Levels ◽  
Almost All ◽  
Saline Solutions ◽  
The Impact

The study was conducted to investigate the impact of Ca(NO3)2 on  different levels of salt-stress in date palm. Three-years-old date palm plants were subjected to four NaCl levels: 50, 100, 150 and 200 mM. The saline solutions were supplemented with 0, 5, 10 and 20 mM Ca(NO3)2. The combined NaCl/Ca(NO3)2 treatments were conducted over a period of 10 weeks. Control plants were only subjected to the four salinity levels with no Ca (NO3)2 addition. Results showed an inhibitory effect of salinity on almost all plants' parameters under investigation, mainly the accumulation of ions such as N, K, Ca, plant dry weight, chlorophyll and net photosynthesis rate. Addition of Ca (NO3)2 in the solution was more beneficial when added in a moderate concentration (10 mM) compared to lower (5 mM) and higher (20 mM) under all salinity levels. The addition of 10 mM Ca (NO3)2 noticeably enhanced chlorophyll content under 50 mM Na Cl (2.5 mg/100 cm2) and 150 mM NaCl (2 mg/100 cm2). In addition, 10 mM Ca (NO3)2 reduced the accumulation of Na and Cl in plant parts. For instance, in trees subjected to 10 mM Ca (NO3)2, Cl content in leaves and stems under 50 mM Na Cl were 0.23% and 0.65%, respectively. On the other hand, Cl content under 100 mM Na Cl and 200 mM Na Cl were lower compared to their corresponding control treatments. It seems that the use of Ca (NO3)2 had ameliorative effects on salt-stressed date palm plants when used with moderate concentrations.

scholarly journals Effect of fertigation with potassium and nitrogen on gas exchange and biomass accumulation in eggplant1

2017 ◽  
Vol 47 (3) ◽  
pp. 345-352
Author(s):  
Álvaro Henrique Cândido de Souza ◽  
Roberto Rezende ◽  
Marcelo Zolin Lorenzoni ◽  
Fernando André Silva Santos ◽  
André Maller
Keyword(s):  
Stomatal Conductance ◽  
Gas Exchange ◽  
Water Use ◽  
Biomass Accumulation ◽  
Net Photosynthesis ◽  
Dry Weight ◽  
Co2 Concentration ◽  
Internal Co2 ◽  
Use Efficiency ◽  
Total Dry Weight

ABSTRACT Adequate crop fertilization is one of the challenges for agriculture. Measuring gas exchange and biomass accumulation may be used to adjust crop management. The effect of fertigation with potassium (0 kg ha-1, 54 kg ha-1, 108 kg ha-1 and 216 kg ha-1) and nitrogen (0 kg ha-1, 67 kg ha-1, 134 kg ha-1 and 268 kg ha-1) on gas exchange and biomass accumulation in eggplant was assessed under greenhouse conditions. The net photosynthesis, stomatal conductance, transpiration, internal CO2 concentration, instantaneous carboxylation efficiency, water-use efficiency and total dry weight were evaluated. With the exception of K for water-use efficiency and N for internal CO2 concentration, all the other gas exchange parameters were significantly affected by the K and N doses. There was an interaction between N and K doses for net photosynthesis, stomatal conductance, transpiration and instantaneous carboxylation efficiency. The highest values for net photosynthesis, stomatal conductance, transpiration rate, carboxylation instantaneous efficiency and total dry weight were found in the range of 125-185 kg ha-1 of K and 215-268 kg ha-1 of N.

Growth, yield and plant-water relations of four cowpea (Vigna unguiculata) cultivars in the Sahel

1996 ◽  
Vol 126 (2) ◽  
pp. 183-190 ◽  
Author(s):  
M. V. K. Sivakumar ◽  
B. R. Ntare ◽  
J. M. Roberts
Keyword(s):  
Stomatal Conductance ◽  
Water Use ◽  
Vigna Unguiculata ◽  
Growth Yield ◽  
Net Photosynthesis ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Dual Purpose ◽  
Area Index ◽  
Photosynthetic Rates

SUMMARYThe response of four cowpea (Vigna unguiculata(L.) Walp.) cultivars to the warm, semi-arid tropical environment at the ICRISAT Sahelian Center at Sadore, Niger was studied during 1985 and 1986 interms of leaf area index (LAI), dry matter (DM) accumulation, net photosynthesis, stomatal conductance, total water use and yield. Among the three improved cultivars, IT82D–716 is early and erect, cv. IT83S–947 is early and spreading and cv. TVX4659–03E is a medium-duration, highyielding, dual-purpose type. The local cv. Sadore Local is a long-duration, photosensitive, spreading type used mainly for fodder. In both years, Sadore Local recorded the highest LAI. IT82D–716 and IT83S–947 produced < 1·3 t/ha of DM in both years, whereas TVX 4659–03E produced > 2 t/ha of DM and proved superior to Sadore Local in partitioning DM into pods. The four cultivars did not differ significantly either in stomatal conductance or in net phytosynthetic rates. Observed maximum photosynthetic rates of c. 20 μmol/m2/s lie at the bottom of the range 21–38 μmol/m2/s reported for 31 cowpea genotypes in an earlier study. Photosynthetic rates increased with increasing photon flux density. TVX4659–03E had an advantage in total seed plus fodder yields while the local cultivar gave significantly greater fodder yields in both years. Seed and fodder yields, as well as water-use efficiency, confirmed the advantages offered by the dual-purpose cultivar TVX4659–03E. Future breeding efforts in the Sahel should focus on dual-purpose (grain/fodder) cowpea types.

scholarly journals (432) Heat-tolerant Traits of Salvia (Salvia splendens)

HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 1076B-1076
Author(s):  
Seenivasan Natarajan ◽  
Jeff Kuehny
Keyword(s):  
Heat Stress ◽  
Stomatal Conductance ◽  
Plant Growth ◽  
Net Photosynthesis ◽  
Dry Weight ◽  
High Temperature Stress ◽  
Flowering Plant ◽  
Salvia Splendens ◽  
Subsequent Exposure ◽  
Heat Tolerant

One of the greatest impediments to the production of marketable ornamental herbaceous plants in the southern U.S. is high temperature stress. Exposure of plants to sublethal temperature (heat preconditioning) prior to sustained heat stress helps some plants to tolerate subsequent heat stress, a phenomenon often referred as acquired thermotolerance. The objective of this experiment was to examine various morphological, physiological, and anatomical responses of two red varieties of each of the `Vista' (heat tolerant) and `Sizzler' (heat sensitive) series of Salvia splendens to heat preconditioning (HC) and subsequent heat stress treatments [challenging temperatures (CT)]. Cultivars of salvia were subjected to short duration (3 hours) HC of 35 °C every third day until 5 weeks after germination and subsequent exposure to two CT treatments: 30/23 °C and 35/28 °C (day/night) cycles in growth chambers until flowering. Plant growth, marketable quality, stomatal conductance and net photosynthesis declined for `Sizzler' without HC treatment. Compared with nonpreconditioned plants, heat-preconditioned `Sizzler' had 38.28% higher root dry weight, 95% greater leaf thickness, and 50% higher marketable quality at 35/28 °C heat stress condition. Heat preconditioning helped both `Vista' and `Sizzler' to survive in both the heat stress treatments. `Vista' had greater heat-tolerant traits than `Sizzler'; these traits were enhanced with heat preconditioning treatment. The results demonstrated that heat preconditioning enhanced heat tolerance in varieties of salvia, which could be related to heat-tolerant traits, such as dense plant growth with shorter internodes, thicker stems, greater stomatal conductance, and extensive root growth that compensated for the transpiration water loss and cooling effect.

scholarly journals SHORT DURATION HEAT PRECONDITIONING AND HEAT TOLERANCE IN ORNAMENTAL BEDDING PLANTS

HortScience ◽  
2005 ◽  
Vol 40 (3) ◽  
pp. 874d-874
Author(s):  
Seenivasan Natarajan ◽  
Jeff S. Kuehny ◽  
James E. Board
Keyword(s):  
Heat Stress ◽  
Stomatal Conductance ◽  
Plant Growth ◽  
Short Duration ◽  
Heat Tolerance ◽  
Net Photosynthesis ◽  
Dry Weight ◽  
High Temperature Stress ◽  
Bedding Plants ◽  
Heat Tolerant

One of the greatest impediments to production of marketable ornamental herbaceous plants in southern U.S. is high temperature stress. Exposure of plants to sub-lethal temperature (heat preconditioning) before sustained heat stress helps some plants to tolerate subsequent heat stress a phenomenon often referred as acquired thermotolerance. The objective of this research was to examine various morphological, physiological and anatomical responses of `Vista red' (heat tolerant) and `Sizzler red'(heat sensitive) cultivars of Salvia splendens to heat preconditioning (HC) and subsequent heat stress treatments (challenging temperatures, CT). Cultivars of Salvia were subjected to short duration HC of 35 °C for 3 hours every third day until 5 weeks after germination and subsequent exposure to two CT treatments 30/23 °C and 35/28 °C (D/N) cycles in growth chambers for the next five weeks. Plant growth, marketable quality, stomatal conductance and net photosynthesis declined for Sizzler Red without HC treatment. Compared with nonpreconditioned plants, heat preconditioned Sizzler Red had 38.28% higher root dry weight, 95% greater leaf thickness, 50% higher marketable quality at 35/28 °C heat stress condition. Heat preconditioning helped both Vista Red and Sizzler to survive in both the heat stress treatments. Vista Red had greater heat tolerant traits than Sizzler Red, these traits exacerbated with heat preconditioning treatment. The results demonstrated that heat preconditioning enhanced heat tolerance in cultivars of Salvia, which could be related to maintenance of dense plant growth with shorter internodes, thicker stems, greater stomatal conductance, extensive root growth that compensated the transpirational water loss and overall cooling of plants.

scholarly journals 427 PB 162 INTERACTIONS BETWEEN POTASSIUM AND OTHER MINERAL ELEMENTS IN DROUGHT STRESSED AND NON-DROUGHT STRESSED HIBISCUS SINENSIS L. CV. LEPRECAUN

HortScience ◽  
1994 ◽  
Vol 29 (5) ◽  
pp. 492d-492
Author(s):  
Jonathan N. Egilia ◽  
Fred T. Davies ◽  
Sharon Duray
Keyword(s):  
Drought Stress ◽  
Nutrient Solution ◽  
Isotope Composition ◽  
Stable Carbon Isotope ◽  
Net Photosynthesis ◽  
Dry Weight ◽  
Mineral Elements ◽  
Total Plant ◽  
Use Efficiency ◽  
K Concentration

Hibiscus plants, were irrigated with full strength Hoagland's nutrient solution containing either 0,2,5, or 10 mM potasium(K). After 72 days of K treatment, half of the plants at each K level were subjected to a 21-day slowly developing drought stress cycle and the other half were non-drought stressed (ND). Mid-day leaf water potentials at day 21 was-1.5 to-1.6 MPa (DS), and -0.5 MPa (ND). Leaf K concentration increased with increasing K in nutrient solution for both DS and ND plants, but K was higher in DS than ND plants at 2.5 and 10 mM K. Of the macronutrient cations, only (Ca) was inversely correlated with nutrient solution K, in both DS and ND plants. Leaf concentrations of all the micronutrient cations increased with increasing K supply, regardless of drought stress. Potassium hadt significant positive correlation with total plant and leaf dry weight of DS, but not ND plants. Leaf stable carbon isotope composition (δ13 C,an estimate of long term water-use efficiency), was positively correlated with N, Mg and Ca, and negatively correlated with K, iron (Fe), and K:total cation ratio regardless of drought stress. Both net photosynthesis and stomatal conductance were negatively correlated with N and Ca, but positively correlated with K, Fe and manganese in ND plants.

scholarly journals Isoprene emission and photosynthesis during heatwaves and drought in black locust

2017 ◽  
Vol 14 (15) ◽  
pp. 3649-3667 ◽  
Author(s):  
Ines Bamberger ◽  
Nadine K. Ruehr ◽  
Michael Schmitt ◽  
Andreas Gast ◽  
Georg Wohlfahrt ◽  
...  
Keyword(s):  
Heat Stress ◽  
Drought Stress ◽  
Stomatal Conductance ◽  
Gas Exchange ◽  
Black Locust ◽  
Leaf Gas Exchange ◽  
Net Photosynthesis ◽  
Response Curves ◽  
Drought Treatment ◽  
Isoprene Emission

Abstract. Extreme weather conditions like heatwaves and drought can substantially affect tree physiology and the emissions of isoprene. To date, however, there is only limited understanding of isoprene emission patterns during prolonged heat stress and next to no data on emission patterns during coupled heat–drought stress or during post-stress recovery. We studied gas exchange and isoprene emissions of black locust trees under episodic heat stress and in combination with drought. Heatwaves were simulated in a controlled greenhouse facility by exposing trees to outside temperatures +10 °C, and trees in the heat–drought treatment were supplied with half of the irrigation water given to heat and control trees. Leaf gas exchange of isoprene, CO2 and H2O was quantified using self-constructed, automatically operating chambers, which were permanently installed on leaves (n = 3 per treatment). Heat and combined heat–drought stress resulted in a sharp decline of net photosynthesis (Anet) and stomatal conductance. Simultaneously, isoprene emissions increased 6- to 8-fold in the heat and heat–drought treatment, which resulted in a carbon loss that was equivalent to 12 and 20 % of assimilated carbon at the time of measurement. Once temperature stress was released at the end of two 15-day-long heatwaves, stomatal conductance remained reduced, while isoprene emissions and Anet recovered quickly to values of the control trees. Further, we found that isoprene emissions covaried with Anet during nonstress conditions, while during the heatwaves, isoprene emissions were not related to Anet but to light and temperature. Under standard air temperature and light conditions (here 30 °C and photosynthetically active radiation of 500 µmol m−2 s−1), isoprene emissions of the heat trees were by 45 % and the heat–drought trees were by 27 % lower than in control trees. Moreover, temperature response curves showed that not only the isoprene emission factor changed during both heat and heat–drought stress, but also the shape of the response. Because introducing a simple treatment-specific correction factor could not reproduce stress-induced isoprene emissions, different parameterizations of light and temperature functions are needed to describe tree isoprene emissions under heat and combined heat–drought stress. In order to increase the accuracy of predictions of isoprene emissions in response to climate extremes, such individual stress parameterizations should be introduced to current BVOC models.

scholarly journals Isoprene emission and photosynthesis during heat waves and drought in black locust

2017 ◽  
Author(s):  
Ines Bamberger ◽  
Nadine K. Ruehr ◽  
Michael Schmitt ◽  
Andreas Gast ◽  
Georg Wohlfahrt ◽  
...  
Keyword(s):  
Drought Stress ◽  
Stomatal Conductance ◽  
Gas Exchange ◽  
Black Locust ◽  
Heat Waves ◽  
Leaf Gas Exchange ◽  
Net Photosynthesis ◽  
Weather Conditions ◽  
Linear Functions ◽  
Drought Treatment

Abstract. Extreme weather conditions, like heat waves and drought, can substantially affect tree physiology and the emissions of biogenic volatile organic compounds (BVOC), including isoprene. To date, however, there is only limited understanding of BVOC emission patterns during prolonged heat and coupled heat–drought stress as well as post-stress recovery. To assess the impacts of heat and heat–drought stress on BVOC emissions, we studied gas exchange and isoprene emissions of black locust trees under controlled environmental conditions. Leaf gas exchange of isoprene, CO2 and H2O was quantified using branch chambers connected to a protontransfer-reaction mass spectrometer and an infrared gas analyzer. Heat and heat–drought stress resulted in a sharp decline of photosynthesis and stomatal conductance. Simultaneously, isoprene emissions increased six- to eight-fold in the heat and heat–drought treatment and resulted in a carbon loss that was equivalent to 12 % and 20 % of assimilated carbon at the time of measurement. Once temperature stress was released at the end of two 15 days long heat waves, stomatal conductance remained reduced, while isoprene emissions and photosynthesis recovered quickly to values of the control trees. Further, we found isoprene emissions to co-vary with net photosynthesis during non-stressful conditions, while during the heat waves, isoprene emissions could be solely described by non-linear functions of light and temperature. However, when isoprene emissions betweentreatments were compared under the same temperature and light conditions (e.g., T = 30° C, PAR = 500 µmol m−2 s−1), heat and heat–drought stressed trees would emit less isoprene than control trees. Ourfindings suggest that different parameterizations of light and temperature functions are needed in order to predict tree isoprene emissions under heat and combined heat–drought stress.

scholarly journals PHYSIOLOGICAL RESPONSES OF YOUNG APPLE TREES ON 3 ROOTSTOCKS TO DROUGHT STRESS

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 573a-573 ◽  
Author(s):  
Rodney T. Fernandez ◽  
Ronald L. Perry ◽  
James A. Flore
Keyword(s):  
Chlorophyll Fluorescence ◽  
Drought Stress ◽  
Stomatal Conductance ◽  
Fluorescence Quenching ◽  
Physiological Responses ◽  
Apple Trees ◽  
Stress Cycle ◽  
Before And After ◽  
Variable Chlorophyll Fluorescence ◽  
And Control

`Imperial Gala' on M.9 EMLA, MM.111 and Mark rootstocks were planted in a rain exclusion shelter. Two drought stress periods lasting approximately 1 month each were imposed during 1991. Water was supplied at 2 liters per day per tree before and after each drought cycle while water was withheld from half of the trees during the drought stresses. Maximal and variable chlorophyll fluorescence and fluorescence quenching were significantly reduced by the drought stress with M.111 generally affected first and with the largest difference between drought and control followed by Mark and then M.9. Leaf and stomatal conductance, assimilation and transpiration usually occurred first and were lowest for M.9 followed by Mark and then M.111 during the first stress cycle while Mark responded more rapidly and to a greater extent than M.9 and M.111 during the second stress. Water potential was lower for the stressed trees during both stress periods but osmotic and turgor potentials were reduced only during the first stress period. Changes in water relations were noticed first and to a greater extent for Mark followed by M.9 with M.111 exhibiting the least sensitivity and differences.

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