scholarly journals Xeric Tree Populations Exhibit Delayed Summer Depletion of Root Starch Relative to Mesic Counterparts

Forests ◽  
2020 ◽  
Vol 11 (10) ◽  
pp. 1026
Author(s):  
Scott W. Oswald ◽  
Doug P. Aubrey
Keyword(s):  
Soil Moisture ◽  
Water Stress ◽  
Carbon Allocation ◽  
Soluble Sugar ◽  
Pinus Palustris ◽  
Coarse Roots ◽  
Moisture Availability ◽  
Root Starch ◽  
Soil Moisture Availability

Research linking soil moisture availability to nonstructural carbohydrate (NSC) storage suggests greater NSC reserves promote survival under acute water stress, but little is known about how NSC allocation responds to long-term differences in water availabilty. We hypothesized populations experiencing chronic or frequent water stress shift carbon allocation to build greater NSC reserves for increased survival probability during drought relative to populations rarely experiencing water stress. Over a year, we measured soluble sugar and starch concentrations from branches, stems, and coarse roots of mature Pinus palustris trees at two sites differing in long-term soil moisture availability. Xeric and mesic populations exhibited a cycle of summer depletion-winter accumulation in root starch. Xeric populations reached a maximum root starch concentration approximately 1–2 months later than mesic populations, indicating delayed summer depletion. Xeric and mesic populations reached the same minimum root starch at similar times, suggesting extended winter accumulation for xeric populations. These results suggest seasonal mobilization from root starch is compressed into a shorter interval for xeric populations instead of consistently greater reserves as hypothesized. Seasonal trends differed little between xeric and mesic populations for starch and sugars, suggesting the importance of roots in seasonal carbon dynamics and the primacy of starch for storage. If roots are the primary organ for longterm storage, then our results suggest that whole-plant mobilization and allocation respond to chronic differences in water availability.

Seasonal variation in competitive effect on water stress and pine responses

1994 ◽  
Vol 24 (7) ◽  
pp. 1440-1449 ◽  
Author(s):  
M.A. Perry ◽  
R.J. Mitchell ◽  
B.R. Zutter ◽  
G.R. Glover ◽  
D.H. Gjerstad
Keyword(s):  
Soil Moisture ◽  
Water Stress ◽  
Stomatal Conductance ◽  
Water Potential ◽  
Volume Index ◽  
Integral Approach ◽  
Stem Volume ◽  
Competitive Effects ◽  
Moisture Availability ◽  
Soil Moisture Availability

Plant mixtures were established that differed in both proportion and density of loblolly pine (Pinustaeda L.), sweetgum (Liquidambarstyraciflua L.), and broomsedge (Andropogonvirginicus L.). Soil moisture availability to the pine seedlings was quantified every 2 weeks by measuring predawn xylem pressure potentials. Temporal variation in pine water potential was accounted for by a water stress integral approach. Cumulative water stress integral values were calculated over four overlapping periods, from May to June, May to July, May to August, and May to September and compared with the mean seedling stem volume index at each period to determine competitive responses at the whole plant scale. Diurnal measures of stomatal conductance were taken each month to compare competitive responses at the leaf scale. In addition, environmental and plant responses that may control stomatal behavior were quantified. The pine water stress integral was strongly influenced by competing vegetation after the onset of a period of drought in early summer. The correlation between the water stress integral and pine growth increased after a significant drying period, accounting for more than half of the variation in stem volume index at the end of the first growing season. Stomatal conductance was also influenced by competition, with competitive effects more evident during times of drought. Conductance was most often related to bulk leaf water potential, which in turn was related to competitive effects on soil moisture availability. Vapor pressure deficit also influenced stomatal conductance, but this was largely unrelated to competitive effects.

Responses of two hybrid Populus clones to flooding, drought, and nitrogen availability. I. Morphology and growth

1992 ◽  
Vol 70 (11) ◽  
pp. 2265-2270 ◽  
Author(s):  
Zhijun Liu ◽  
Donald I. Dickmann
Keyword(s):  
Soil Moisture ◽  
Water Stress ◽  
Nitrogen Availability ◽  
Carbon Allocation ◽  
Hybrid Poplar ◽  
Leaf Expansion ◽  
Root Production ◽  
Leaf Initiation ◽  
Stem Biomass ◽  
Nitrogen Levels

Repeated progressive drought and flooding stress were imposed on hybrid poplar clones Populus × euramericana 'Eugenei', and Populus tristis × Populus balsamifera ‘Tristis’ grown in pots in a greenhouse under two nitrogen levels. In both clones the rate of leaf initiation was promoted only in high-N plants subjected to minimum water stress. Water stress alone did not retard the rate of leaf initiation, but it significantly reduced leaf expansion of 'Eugenei', whereas only flooding led to smaller leaves in 'Tristis'. The addition of N stimulated leaf expansion, leaf chlorophyll and N concentrations, and leaf and stem biomass production across soil moisture levels, but the greatest effect of N was associated with minimum water stress. High N altered carbon allocation towards the aboveground portions, leading to lower root to shoot ratios. High N also appeared to stimulate initiation of fine roots. Soil moisture determined the amount of biomass that accumulated in roots, with highest root production in well-watered pots and lowest in flooded pots, with the droughted treatment in between. Leaves became thinner as soil moisture decreased from flooding. Stem biomass of 'Tristis' declined more under flooding than under drought, whereas 'Eugenei' displayed a greater reduction of stem biomass in droughty than in flooded soil. Key words: water stress, nitrogen, leaf and root morphology, root to shoot ratio, biomass, Populus, flooding.

scholarly journals The impact of drought stress on the yields and food value of selected forage grasses

2016 ◽  
Vol 69 (2) ◽  
Author(s):  
Mariola Staniak
Keyword(s):  
Soil Moisture ◽  
Water Stress ◽  
Drought Stress ◽  
Dry Matter ◽  
Nutritional Value ◽  
Lolium Multiflorum ◽  
Grass Species ◽  
Forage Grasses ◽  
The Impact

<p>The aim of the study was to compare yields and nutritional value of selected species and cultivars of forage grasses under the optimal moisture conditions and long-term drought stress. The regenerative capacity of plants after dehydration was also assessed. The pot experiment was conducted in years 2009–2010 in IUNG-PIB’s greenhouse in Puławy, Poland. Nine cultivars of four species: <em>Dactylis glomerata</em> (‘Amera’, ‘Minora’), <em>Festuca pratensis</em> (‘Skra’, ‘Fantazja’), <em>Festulolium braunii</em> (‘Felopa’, ‘Agula’, ‘Sulino’), and <em>Lolium multiflorum</em> (‘Gisel’, ‘Lotos’) were investigated in well-watered conditions (70% field water capacity – FWC) and under a long-term drought stress (40% FWC).</p><p>The study showed that stress caused by soil moisture deficiency significantly reduced yields of <em>D. glomerata</em>, <em>F. pratensis</em>, <em>F. braunii</em>, and <em>L. multiflorum</em>. The total yield of dry matter under stress conditions was about 31% lower, compared to the performance achieved on the optimally moisturized treatment. The smallest reduction in dry matter yield under the conditions of water deficit was recorded for <em>D. glomerata</em>, which makes it the most resistant to stress, followed by <em>F. pratensis</em>. The resistance of <em>F. braunii</em> and <em>L. multiflorum</em> to stress was similar and significantly lower. There was a various response of different grasses to the water stress. On the basis of the value of the DSI (drought susceptibility index), the tested cultivars were ranked depending on the sensitivity to drought, starting with the most resistant cultivar: ‘Minora’, ‘Skra’, ‘Fantazja’, ‘Amera’, ‘Sulino’, ‘Agula’, ‘Gisel’, ‘Lotos’, and ‘Felopa’. The digestibility of dry matter and nutrient value of the grasses depended on both the level of soil moisture and grass species. Under the water stress, the digestibility and protein value increased compared to the control objects. <em>Lolium multiflorum</em> and <em>F. braunii</em> had the best nutritional value, while <em>D. glomerata</em> – the weakest.</p>

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