scholarly journals Features Of Photosynthesis And Water Regime Of Quercus Pubescens Willd. Under The Conditions Of Autumn Drought Of The Southern Coast Of The Crimea

2021 ◽  
Vol 39 ◽  
pp. 01003
Author(s):  
O.A. Ilnitsky ◽  
Y.V. Plugatar ◽  
A.V. Pashtetsky ◽  
A.T. Gil
Keyword(s):  
Soil Moisture ◽  
Net Photosynthesis ◽  
Leaf Temperature ◽  
Photosynthesis Rate ◽  
Soil Drought ◽  
Quercus Pubescens ◽  
Net Photosynthesis Rate ◽  
The Crimea ◽  
Optimal Values ◽  
The Relationship

The objective of the research is to determine the optimal zones and thresholds of soil moisture, temperature, illumination, limiting photosynthesis and transpiration of Quércus pubéscens Willd. and allowing the introduction of the species to other regions. The dependences of the net photosynthesis rate (Pn) and the transpiration rate (E) on stomatal conductivity (gs), leaf temperature (Tl), and soil moisture (Ws) are shown. The ratio of the processes of photosynthesis and respiration, under the influence of soil drought, allowed us to define their optimal values: Ws = 26 – 28%, Pn = 16 –18 μmol/m2c, Rt = 2 – 4 μmol/m2c. The relationship between the net photosynthesis rate, total respiration, and leaf temperature allowed us to determine the temperature maximum of net photosynthesis (the thermal compensation point): Pn = Rt = 2.0 μmol/m2c at Tl = 37ºC. It was found that in the absence of soil drought, the proportion of respiratory costs (Rt/Pg) from true photosynthesis is 20 – 23%, and with soil moisture of 8 – 10% increases to 55 – 58%.

scholarly journals Research on Occurrence and Development of Pasture Drought Events in Alpine Grassland using the Drought Threshold

2018 ◽  
Author(s):  
Tiaofeng Zhang ◽  
Lin Li ◽  
Hongbin Xiao ◽  
Hongmei Li
Keyword(s):  
Soil Moisture ◽  
Alpine Grassland ◽  
Soil Drought ◽  
Severe Drought ◽  
Drought Event ◽  
Drought Intensity ◽  
Quantitative Expression ◽  
Initial Soil Moisture ◽  
Initial Soil ◽  
The Relationship

Abstract. Pasture is vital to livestock husbandry development in Qinghai and even in North China. Drought is the primary meteorological disaster that affects pasture, but insufficient soil moisture is the most prominent cause of pasture drought. Timely and accurate determination of the soil moisture threshold of pasture is important for objective recognition and monitoring of the occurrence and development of pasture drought. This study aims at investigating pasture responses to soil drought as well as quantitative expression of soil drought degree and drought threshold. Test plots were selected from the pasture test station. Five testing groups were set according to coverage rate (0–100 %) at the initiation the pasture growth period. The impacts of profile moisture characteristics, drought threshold, and precipitation on duration of pasture drought were studied. Research results have demonstrated that moisture in the soil profile below 20 cm decreases slightly throughout drought events in alpine grassland. Changes of soil moisture in the 0–20 cm layer can generally reflect drought stress of the pasture. In the process of a drought event, the relationship between soil water storage and cumulative relative water loss can be expressed via a logarithmic linear equation. Quantitative expression of drought degree in grasslands can be realized by transforming the slope of this equation into the index D with an interval of [0, 1]. The occurrence rates of mild drought,moderate drought, and severe drought were 0.36, 0.45, and 0.70, respectively. The duration of severe drought was closely related with initial soil moisture. The relationship between duration of drought and the necessary minimum precipitation can be expressed by an exponential equation. Values of the D index can express soil drought intensity and pasture drought intensity. The durations for different grades of drought events were correlated with both initial soil moisture and previous precipitation. The conclusions of this study can provide scientific references for the objective understanding onoccurrence, development, monitoring, and early warning of pasture drought.

Water stress preconditioning of black spruce seedlings from lowland and upland sites

1994 ◽  
Vol 72 (10) ◽  
pp. 1511-1518 ◽  
Author(s):  
Abdenbi Zine El Abidine ◽  
Pierre Y. Bernier ◽  
James D. Stewart ◽  
André P. Plamondon
Keyword(s):  
Water Relations ◽  
Black Spruce ◽  
Sugar Content ◽  
Net Photosynthesis ◽  
Soil Drought ◽  
Drought Period ◽  
Gas Exchanges ◽  
Total Sugar Content ◽  
Net Photosynthesis Rate ◽  
One Year

One-year-old seedlings from two pairs of upland – lowland populations were subjected to three cycles of drought preconditioning. During a subsequent fourth cycle, preconditioned seedlings and seedlings that had been maintained under well-watered conditions were subjected to a final soil drought. During the drought periods, small but significant differences in gas exchanges and water relations were observed between upland and lowland seedlings but the differences were not consistent either within each lowland – upland pair or over the four cycles. During the final drought period, preconditioned seedlings maintained significantly higher net photosynthesis rate, stomatal conductance, and transpiration rate than unconditioned seedlings. In contrast, no significant differences were found in midday water potential, total sugar content, or water relations parameters between preconditioned and unconditioned seedlings. The results suggest an absence of ecotypic variation with respect to drought tolerance in black spruce. They also suggest that preconditioning in black spruce seedlings occurs mostly through the acclimation of stomatal and photosynthetic mechanisms to drought, without active osmotic adjustment. Key words: Picea mariana, ecotype, gas exchanges, water relations, osmoregulation, preconditioning.

scholarly journals Allelopathic Effects of Water Extracts of Maize Leaf on Three Chinese Herbal Medicinal Plants

2018 ◽  
Vol 47 (1) ◽  
pp. 194-200 ◽  
Author(s):  
Xiaobang PENG
Keyword(s):  
Medicinal Plants ◽  
Aqueous Extract ◽  
Seedling Growth ◽  
Salvia Miltiorrhiza ◽  
Net Photosynthesis ◽  
Photosynthesis Rate ◽  
Maize Leaf ◽  
Scutellaria Baicalensis Georgi ◽  
Net Photosynthesis Rate ◽  
Low Concentrations

Plants generate various secondary metabolites named as allelochemicals that can be release into the environment and influence the growth and development of other plants or the same plant. The potential allelopathic effect of maize (Zea mays L.) on seed germination, seedling growth and physiology was investigated with three medicinal plants (Platycodon grandiflorum A.DC, Scutellaria baicalensis Georgi and Salvia miltiorrhiza Bge) with different concentrations (0, 0.5%, 1.0%, 2.5%, 5.0%, 10.0%). Low concentrations (0.5%, 1.0%) of maize leaf aqueous extract stimulated the germination and seedling growth (root length, shoot height, fresh weight) of all receptor plants significantly. With the concentration of the aqueous extract increased, the stimulating effects gradually decreased, and even changed into inhibited. The aqueous leachate of maize leaves exerted different allelopathic effects on physiology of different test medicinal plants. For Platycodon grandiflorum A.DC, there was no significant difference in photosynthesis rate at all the tested concentration compared with control. In Scutellaria baicalensis Georgi the lower concentration (0.5%, 1.0%, 2.5%) of leachates stimulated the net photosynthesis rate, yet the higher concentration (5.0%, 10.0%) decreased the net photosynthesis rate, and all the tested concentration have inhibited effects on Salvia miltiorrhiza Bge and decreased its net photosynthesis rate. However, the content of soluble sugar and soluble protein of all receptor plants were stimulated by low concentrations (0.5%, 1.0%, 2.5%) of maize leaf aqueous extract. Allelopathy can affect the seed germination, early seedling growth and physiology of three medicinal plants.

scholarly journals Possibility of Increasing the Growth and Photosynthetic Properties of Precocious Walnut by Grafting

2020 ◽  
Vol 12 (12) ◽  
pp. 5178
Author(s):  
Yongchao Bai ◽  
Junpei Zhang ◽  
Yue Wu ◽  
Ruimin Huang ◽  
Yingying Chang ◽  
...  
Keyword(s):  
Plant Growth ◽  
Transpiration Rate ◽  
Survival Rates ◽  
Net Photosynthesis ◽  
Growth Characteristics ◽  
Photosynthesis Rate ◽  
Growth Potential ◽  
Net Photosynthesis Rate ◽  
Photosynthetic Properties ◽  
Plant Growth Characteristics

Plant growth characteristics after grafting are mainly dependent on photosynthesis performance, which may be influenced by grafting combinations with different rootstocks and scions. In this study, we used one-year-old walnut grafts to investigate the grafting compatibility between precocious (‘Liaoning 1’, L) and hybrid (‘Zhong Ning Sheng’, Z) walnut, as well as rootstock and scion impact on the growth and photosynthetic properties of walnut trees. The results showed that grafting compatibility between the two varieties is high, with survival rates upward of 86%. Overwintering survival of grafted seedlings was as high as 100%, which indicated that the allopolyploid had good resistance to low-temperature stress. The homograft of the hybrid walnut had the highest net photosynthesis rate (18.77 μmol·m−2s−1, Z/Z) and growth characteristics, which could be due to its higher transpiration rate and stomatal conductance, whereas the homograft of precocious walnut presented the lowest net photosynthesis rate (15.08 μmol·m−2s−1, L/L) and growth characteristics. Significant improvements in the net photosynthesis rate (15.97 and 15.24 μmol·m−2s−1 for L/Z and Z/L, respectively) and growth characteristics of precocious walnut were noticed during grafting of the hybrid walnut, which could have been contributed by their transpiration rate. The results of this study serve as a guide for the selection and breeding of good rootstock to improve plant growth characteristics and photosynthetic efficiency. We conclude that good rootstock selection improves plant growth potential and could play an important role in sustainable production.

scholarly journals Investigating the variations of soil fertility and Sorghum bicolor L. physiological performance under plantation of some Acacia species

2020 ◽  
Vol 66 (No. 1) ◽  
pp. 33-40
Author(s):  
Abdalla Ahmed ◽  
Ibrahim Aref ◽  
Thobayet Alshahrani
Keyword(s):  
Stomatal Conductance ◽  
Soil Fertility ◽  
Sorghum Bicolor ◽  
Net Photosynthesis ◽  
Photosynthesis Rate ◽  
Available Nitrogen ◽  
Physiological Performance ◽  
Acacia Species ◽  
Net Photosynthesis Rate ◽  
Sorghum Bicolor L

Taking the importance of agricultural production sustainability with limited resources to use efficiency in an arid area, afield experiment was designed to investigate the effect of three, Acacia trees (Acacia nilotica, A. seyal, and A. tortilis) planting combination on soil fertility and Sorghum bicolor L. growth and physiological performance. The sorghum planted in 7 strips between 14 rows of Acacia trees planting combinations and one treeless strip as control. Acacia species plantations significantly increase soil fertility in terms of available nitrogen (N), phosphorus (P), potassium (K) and organic carbon (OC) contents as compared to control, highest level of N and P content (59.01 ± 1.45 and 58.77 ± 1.10 mg/kg) was reported in strip between rows of A. tortilis. Although the highest net photosynthesis rate (P<sub>n</sub>) and stomatal conductance (g<sub>s</sub>) recorded in plants grown between rows of pure A. torilis, and rows of A. torilis–A. seyal, but different Acacia significantly enhanced sorghum growth and physiology with reference to net photosynthesis rate, stomatal conductance and chlorophyll fluorescence (chlF). The results stated linear relation between soil nutrients (N, P, K), P<sub>n</sub>, and chlF increasing soil fertility improve physiological performance of sorghum. In conclusion, the three Acacia improve soil fertility and sorghum growth. Generally, this plantation trial can be environment-friendly alternative agricultural practices in Saudi Arabia or any area with a similar ecological condition to amend the soil and improve crop performance.

scholarly journals Inducing Resistance in Heliconia psittacorum cv. Golden Torch to Naturally Occurring Leaf Diseases

2018 ◽  
Vol 10 (12) ◽  
pp. 385
Author(s):  
D. H. S. Sardinha ◽  
A. A. C. Rodrigues ◽  
J. R. M. Campos Neto ◽  
L. G. L. Melo ◽  
L. J. M. G. Oliveira ◽  
...  
Keyword(s):  
Photosynthetic Rate ◽  
Plant Pathogens ◽  
Net Photosynthesis ◽  
Photosynthesis Rate ◽  
Visual Estimation ◽  
Naturally Occurring ◽  
Net Photosynthesis Rate ◽  
Necrotic Spots ◽  
Management Alternatives ◽  
Inducing Resistance

One of the bottlenecks to heliconia production is leaf diseases, which have the main characteristic of forming necrotic spots, that can reduce photosynthesis, damage the heliconia bracts and make the flowers unsuitable for commercialisation. The objective of the present study was to identify inducers capable of inducing resistance in H. psittacorum cv. Golden Torch, assessing by enzymatic action the reduction in the severity of the fungus complex associated to the cultivation of this species and verifying the action of the severity in relation to the net photosynthesis rate of the plants. The inducers were applied to the plants using a back spray and during application the plots were protected to prevent the products from drifting. The concentrations applied were Agro-Mos&reg; (10 ml L-1), Bion&reg; (0.5 g L-1), Quartz&reg; (40 ml L-1), potassium phosphite (3 g L-1) and calcium phosphite (3 g L-1). During the experimental cultivation, the severity caused by the fungus complex and the photosynthetic rate of the plants were assessed and plant material was collected to analyse the enzymatic activity. The results indicated that the inducers Bion&reg; and the phosphites applied reduced the fungus complex severity, increased the activity of peroxidase, polifenoloxidase and &beta;-1.3 gluconase but did not cause alterations in the net photosynthesis rate of the plants. The value found for &beta; &gt; 1 suggested that the visual estimation of the fungus complex severity is a good visual indicator of the effect of the plant pathogens on the host photosynthetic rate. The results are concrete responses to producers in the sector on management alternatives for diseases associated to heliconia cultivation.

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