Seasonal trends in photosynthetic parameters and stomatal conductance of blue oak (Quercus douglasii) under prolonged summer drought and high temperature

Almond willow (Salix triandra L.) is a valuable basket species that is used to create plantings for various purposes. He occupies a special place in the system of the genus Salix. He can be used as a model object to identify patterns of morphogenesis of shoots. Object of research: model inbred population of almond willow in culture. Subject of research: seasonal dynamics of internode length on annual shoots of three-year-old seedlings willow of almond willow. The purpose of the research: to identify the seasonal dynamics of the length of internodes on annual shoots of almond willow against the background of a sharp change in early summer drought by cold rainy weather. Empirical methods for obtaining initial data: comparative-morphological. The obtained data were processed using the methods of analysis of dynamics series. It is found that seasonal trends in the dynamics of internode length are described by second-order regression equations with varying reliability. The configuration and topology of nonlinear seasonal trends are determined by individual differences between seedlings. The dynamics of deviations of internode length from seasonal trends correlates with the dynamics of hydrothermic conditions. Deviations in the length of internodes from seasonal trends are cyclical. The empirical series of deviations of the internode length from seasonal trends with high reliability are approximated by the sums of harmonic oscillations. The maximum contribution to the cyclical deviations of the internode length from seasonal trends is made by the rhythm with a period of fluctuations of 54 days. On most shoots, the influence of rhythms with a period of fluctuations of 36 and 27 days can be traced. Short-period rhythms detected on different shoots are irregular. In most observations, the specific rhythms of seasonal dynamics of internode length are determined by differences between shoots. The identified rhythms do not depend on hydrothermic conditions, on the length of shoots, on the length of internodes, or on seasonal trends in the dynamics of internode length. The hypothesis that the relationship between the dynamics of deviations in the length of internodes from seasonal trends and the dynamics of hydrothermic conditions is random is substantiated. Cyclicity deviations of internode length from seasonal trends are determined by endogenous rhythms of development.

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Long-term Growth and Persistence of Blue Oak (Quercus douglasii) Seedlings in a California Oak Savanna

Madroño ◽

10.3120/0024-9637(2007)54[269:lgapob]2.0.co;2 ◽

2007 ◽

Vol 54 (4) ◽

pp. 269-274 ◽

Cited By ~ 6

Author(s):

Walter D. Koenig ◽

Johannes M. H. Knops

Keyword(s):

Oak Savanna ◽

Quercus Douglasii ◽

Blue Oak

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Hotter Drought Escalates Tree Cover Declines in Blue Oak Woodlands of California

Frontiers in Climate ◽

10.3389/fclim.2021.689945 ◽

2021 ◽

Vol 3 ◽

Author(s):

Francis K. Dwomoh ◽

Jesslyn F. Brown ◽

Heather J. Tollerud ◽

Roger F. Auch

Keyword(s):

Land Cover ◽

Land Cover Change ◽

Land Surface ◽

Climatic Variability ◽

Tree Cover ◽

Quercus Douglasii ◽

Oak Woodlands ◽

Vegetation Communities ◽

Blue Oak ◽

Climate Risks

California has, in recent years, become a hotspot of interannual climatic variability, recording devastating climate-related disturbances with severe effects on tree resources. Understanding the patterns of tree cover change associated with these events is vital for developing strategies to sustain critical habitats of endemic and threatened vegetation communities. We assessed patterns of tree cover change, especially the effects of the 2012–2016 drought within the distribution range of blue oak (Quercus douglasii), an endemic tree species to California with a narrow geographic extent. We utilized multiple, annual land-cover and land-surface change products from the U.S. Geological Survey (USGS) Land Change Monitoring, Assessment and Projection (LCMAP) project along with climate and wildfire datasets to monitor changes in tree cover state and condition and examine their relationships with interannual climate variability between 1985 and 2016. Here, we refer to a change in tree cover class without a land-cover change to another class as “conditional change.” The unusual drought of 2012–2016, accompanied by anomalously high temperatures and vapor pressure deficit, was associated with exceptional spikes in the amount of both fire and non-fire induced tree cover loss and tree cover conditional change, especially in 2015 and 2016. Approximately 1,266 km2 of tree cover loss and 617 km2 of tree cover conditional change were recorded during that drought. Tree cover loss through medium to high severity fires was especially large in exceptionally dry and hot years. Our study demonstrates the usefulness of the LCMAP products for monitoring the effects of climatic extremes and disturbance events on both thematic and conditional land-cover change over a multi-decadal period. Our results signify that blue oak woodlands may be vulnerable to extreme climate events and changing wildfire regimes. Here, we present early evidence that frequent droughts associated with climate warming may continue to affect tree cover in this region, while drought interaction with wildfires and the resulting feedbacks may have substantial influence as well. Consequently, efforts to conserve the blue oak woodlands, and potentially other vegetation communities in the Western United States, may benefit from consideration of climate risks as well as the potential for climate-fire and vegetation feedbacks.

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Changes during summer drought in leaf CO2 uptake rates of macchia shrubs growing in Portugal: Limitations due to photosynthetic capacity, carboxylation efficiency, and stomatal conductance

Plant Response to Stress ◽

10.1007/978-3-642-70868-8_18 ◽

1987 ◽

pp. 305-327 ◽

Cited By ~ 26

Author(s):

J. D. Tenhunen ◽

W. Beyschlag ◽

O. L. Lange ◽

P. C. Harley

Keyword(s):

Stomatal Conductance ◽

Photosynthetic Capacity ◽

Carboxylation Efficiency ◽

Summer Drought ◽

Co2 Uptake ◽

Uptake Rates

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Role of mineral nutrition in alleviation of heat stress in cotton plants grown in glasshouse and field conditions

Scientific Reports ◽

10.1038/s41598-019-49404-6 ◽

2019 ◽

Vol 9 (1) ◽

Author(s):

Muhammad Sarwar ◽

Muhammad Farrukh Saleem ◽

Najeeb Ullah ◽

Shafaqat Ali ◽

Muhammad Rizwan ◽

...

Keyword(s):

Heat Stress ◽

High Temperature ◽

Stomatal Conductance ◽

Foliar Spray ◽

Cotton Yield ◽

Seed Cotton ◽

Chlorophyll Contents ◽

Seed Cotton Yield ◽

Boll Weight ◽

Cotton Plants

Abstract Coincidence of high temperature with terminal reproductive pheno-stages of cotton is chief constraint to achieve yield potential. This high temperature interfere plant defensive system, physiological process, water relations and lint yield production. In this study, we modulated the detrimental outcomes of heat stress on cotton through the foliar spray of nutrients. Cotton crop was exposed to sub-optimal and supra-optimal thermal regimes for a period of one week at squaring, flowering and boll formation stages under glass house and field conditions. Foliar spray of potassium (K-1.5%), zinc (Zn-0.2%) and boron (B-0.1%) were applied at three reproductive stages one day prior to expose high temperature regimes. High temperature increased lipid membrane damage through increased malondialdehyde (MDA) contents in cotton leaves. High temperature stress also reduced leaf chlorophyll contents, net photosynthetic rate, stomatal conductance, water potential, averaged boll weight (g) and seed cotton yield per plant. Various nutrients variably influenced growth and physiology of heat-stressed cotton plants. Zinc outclassed all other nutrients in increasing leaf SOD, CAT, POX, AsA, TPC activity, chlorophyll contents, net photosynthetic rate, stomatal conductance, water potential, boll weight and seed cotton yield per plant. For example, zinc improved seed cotton yield under supra-optimal thermal regime by 17% and under sub-optimal thermal regime by 12% of glasshouse study while 19% under high temperature sowing dates of field study than the water treated plants under the same temperatures. Conclusively, increasing intensities of temperature adversely affected the recorded responses of cotton and exogenous application of Zn efficaciously alleviated heat induced perturbations. Moreover, exogenous nutrients mediated upregulations in physiochemical attributes induced heat tolerance at morphological level.

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The Effects of Different Sizes of Tree Shelters on Blue Oak (Quercus douglasii) Growth

Western Journal of Applied Forestry ◽

10.1093/wjaf/16.4.153 ◽

2001 ◽

Vol 16 (4) ◽

pp. 153-158 ◽

Cited By ~ 9

Author(s):

Douglas D. McCreary ◽

Jerry Tecklin

Keyword(s):

Field Performance ◽

Height Growth ◽

Average Height ◽

Quercus Douglasii ◽

Tree Shelters ◽

Blue Oak ◽

Promising Tool ◽

Wide Range ◽

Stock Types ◽

Time Required

Abstract Tree shelters have been used effectively in many locations to establish a wide range of tree species including oaks. However, their efficacy in Mediterranean climates like the hardwood rangelands of California has not been thoroughly tested. This study evaluated the field performance of blue oak (Quercus douglasii)—a species that is reported to be regenerating poorly in many locations in the state—protected by several sizes of tree shelters and compared response of directly sown acorns to that of 4-month-old transplants. After five growing seasons, seedlings in all sizes of tree shelters are larger than their unprotected counterparts. Tree shelters have been especially effective in promoting rapid height growth. However, regardless of tree shelter size, when seedlings grew above the tops of the shelters, average height growth diminished and diameter growth increased. Differences among stock types were relatively small, although transplants tended to perform better than directly sown acorns. These results suggest that tree shelters can greatly reduce the time required by seedlings to grow to a size where they are less vulnerable to browsing. As such, they appear to be a promising tool in efforts to regenerate blue oak in California. West. J. Appl. For. 16(4):153-158.

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