Effects of soil moisture and light intensity on the chasmogamous and cleistogamous components of reproductive effort of Dichanthelium clandestinum populations

1987 ◽  
Vol 65 (11) ◽  
pp. 2243-2249 ◽  
Author(s):  
Timothy J. Bell ◽  
James A. Quinn
Keyword(s):  
Soil Moisture ◽  
Biomass Allocation ◽  
Reproductive Effort ◽  
Environmental Gradients ◽  
Perennial Grass ◽  
Moisture Gradient ◽  
Sharp Drop ◽  
Population Responses ◽  
Steady Decrease ◽  
Significant Difference

Plants from six New Jersey populations of Dichanthelium clandestinum, a perennial grass with chasmogamous and cleistogamous flowers on the same individual, showed significant differences in their responses to decreasing light and soil moisture, but chasmogamous reproductive effort was always less than cleistogamous. In an experiment with three light treatments, populations were significantly different in biomass allocation to chasmogamous and cleistogamous reproduction and varied as to which light treatment produced the most significant difference between chasmogamous and cleistogamous allocation. In an experiment using soil moisture gradient boxes, chasmogamous reproductive effort remained relatively constant over the moisture gradient for all six populations; however, for five populations, percentage biomass allocation to cleistogamous reproduction was significantly lower at low soil moistures. The population responses formed a continuum from no difference in allocation to cleistogamy along the moisture gradient to a sharp drop in cleistogamous allocation at the lower end of the gradient to a relatively steady decrease in cleistogamous allocation with decreasing soil moisture. These results indicate genetically based differences in phenotypic plasticity and underscore the need to use more than one population of a species when research is conducted on variation in relative allocation to chasmogamous and cleistogamous reproduction along environmental gradients.

scholarly journals An individual-based forest model links canopy dynamics and shade tolerances along a soil moisture gradient

2016 ◽  
Vol 3 (2) ◽  
pp. 150589 ◽  
Author(s):  
Jean Liénard ◽  
Nikolay Strigul
Keyword(s):  
Soil Moisture ◽  
Multiple Scales ◽  
Environmental Gradients ◽  
Spatial Competition ◽  
Climatic Changes ◽  
Moisture Gradient ◽  
The North ◽  
Trade Offs ◽  
Shade Tolerant Species ◽  
Closed Canopy

Understanding how forested ecosystems respond to climatic changes is a challenging problem as forest self-organization occurs simultaneously across multiple scales. Here, we explore the hypothesis that soil water availability shapes above-ground competition and gap dynamics, and ultimately alters the dominance of shade tolerant and intolerant species along the moisture gradient. We adapt a spatially explicit individual-based model with simultaneous crown and root competitions. Simulations show that the transition from xeric to mesic soils is accompanied by an increase in shade-tolerant species similar to the patterns documented in the North American forests. This transition is accompanied by a change from water to sunlight competitions, and happens at three successive stages: (i) mostly water-limited parkland, (ii) simultaneously water- and sunlight-limited closed canopy forests featuring a very sparse understory, and (iii) mostly sunlight-limited forests with a populated understory. This pattern is caused by contrasting successional dynamics that favour either shade-tolerant or shade-intolerant species, depending on soil moisture and understory density. This work demonstrates that forest patterns along environmental gradients can emerge from spatial competition without physiological trade-offs between shade and growth tolerance. Mechanistic understanding of population processes involved in the forest–parkland–desert transition will improve our ability to explain species distributions and predict forest responses to climatic changes.

scholarly journals Grapevine and Soil Water Relations with Nodding Needlegrass (Nassella cernua), a California Native Grass, as a Cover Crop

HortScience ◽  
2010 ◽  
Vol 45 (4) ◽  
pp. 621-627 ◽  
Author(s):  
Michael J. Costello
Keyword(s):  
Soil Moisture ◽  
Soil Water ◽  
Water Relations ◽  
Cover Crop ◽  
Water Status ◽  
Perennial Grass ◽  
Native Grass ◽  
Significant Difference ◽  
Vineyard Soil ◽  
Native Perennial Grass

Nodding needlegrass [Nassella cernua (Stebbins & R.M. Love) Barkworth], a California native perennial grass, was tested for its effects on grapevine and soil–water relations in a drip-irrigated vineyard in Parlier, CA. Vine water status and in-row and between-row soil moisture (at 0.3 m, 0.6 m, 0.9 m, 1.2 m, and 1.5 m) were monitored semiweekly from June to September. There was no overall significant difference in leaf water potential between treatments. In-row soil moisture was lowest at depths of 0.6 m to 0.9 m within the nodding needlegrass treatment but was lowest from 0.3 m to 0.9 m within the clean cultivation treatment. Compared with clean cultivation, nodding needlegrass in-row soil moisture was significantly higher at depths of 0.3 m and 0.6. m and did not differ at depths of 0.9 m and 1.2 m. In contrast, in-row soil moisture was significantly higher under clean cultivation compared with nodding needlegrass at 1.5 m. Between-row soil moisture was significantly higher under clean cultivation compared with nodding needlegrass at every depth. Combining in-row and between-row data, overall vineyard soil moisture was slightly lower, by 1.2% points, in the nodding needlegrass treatment compared with clean cultivation. There was no interaction between treatment and depth for between-row soil moisture, indicating that the vines used little water from the between-row area. The lack of difference between treatments in the rate of soil moisture depletion over the season indicates that nodding needlegrass used little water during the summer. Based on these results, nodding needlegrass appears to be suitable as a permanent cover crop in California drip-irrigated vineyards where competition for summer water is a concern.

scholarly journals Effects of Irrigation and Nitrogen Fertilization on Seed Yield, Yield Components, and Water Use Efficiency of Cleistogenes songorica

Agronomy ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 466
Author(s):  
Qibo Tao ◽  
Mengjie Bai ◽  
Cunzhi Jia ◽  
Yunhua Han ◽  
Yanrong Wang
Keyword(s):  
Water Use Efficiency ◽  
Water Use ◽  
Seed Yield ◽  
Yield Components ◽  
Perennial Grass ◽  
Yield Component ◽  
Path Coefficient ◽  
Grass Seed ◽  
Significant Difference ◽  
Use Efficiency

Irrigation and nitrogen (N) are two crucial factors affecting perennial grass seed production. To investigate the effects of irrigation and N rate on seed yield (SY), yield components, and water use efficiency (WUE) of Cleistogenes songorica (Roshevitz) Ohwi, an ecologically significant perennial grass, a four-year (2016–2019) field trial was conducted in an arid region of northwestern China. Two irrigation regimes (I1 treatment: irrigation at tillering stage; I2 treatment: irrigation at tillering, spikelet initiation, and early flowering stages) and four N rates (0, 60, 120, 180 kg ha−1) were arranged. Increasing amounts of both irrigation and N improved SY, evapotranspiration, WUE, and related yield components like fertile tillers m−2 (FTSM) and seeds spikelet−1. Meanwhile, no significant difference was observed between 120 and 180 kg N ha−1 treatments for most variables. The highest SY and WUE was obtained with treatment combination of I2 plus 120 kg N ha−1 with four-year average values of 507.3 kg ha−1 and 1.8 kg ha−1 mm−1, respectively. Path coefficient and contribution analysis indicated that FTSM was the most important yield component for SY, with direct path coefficient and contribution coefficient of 0.626 and 0.592. Overall, we recommend I2 treatment (three irrigations) together with 120 kg N ha−1 to both increase SY and WUE, especially in arid regions. Future agronomic managements and breeding programs for seed should mainly focus on FTSM. This study will enable grass seed producers, plant breeders, and government program directors to more effectively target higher SY of C. songorica.

EFFECT OF DEFICIT IRRIGATION ON YIELD, RELATIVE LEAF WATER CONTENT, LEAF PROLINE ACCUMULATION AND CHLOROPHYLL STABILITY INDEX OF COTTON–MAIZE CROPPING SEQUENCE

2013 ◽  
Vol 50 (3) ◽  
pp. 407-425 ◽  
Author(s):  
T. SAMPATHKUMAR ◽  
B. J. PANDIAN ◽  
P. JEYAKUMAR ◽  
P. MANICKASUNDARAM
Keyword(s):  
Soil Moisture ◽  
Water Stress ◽  
Water Content ◽  
Deficit Irrigation ◽  
Stability Index ◽  
Moisture Gradient ◽  
Proline Content ◽  
Leaf Water Content ◽  
Chlorophyll Stability Index ◽  
Soil Moisture Gradient

SUMMARYWater stress induces some physiological changes in plants and has cumulative effects on crop growth and yield. Field experiments were conducted to study the effect of deficit irrigation (DI) on yield and some physiological parameters in cotton and maize in a sequential cropping system. Creation of soil moisture gradient is indispensable to explore the beneficial effects of partial root zone drying (PRD) irrigation and it could be possible only through alternate deficit irrigation (ADI) practice in paired row system of drip layout that is commonly practiced in India. In the present study, PRD and DI concepts (creation of soil moisture gradient) were implemented through ADI at two levels of irrigation using drip system. Maize was sown after cotton under no till condition without disturbing the raised bed and drip layout. Relative leaf water content (RLWC) and chlorophyll stability index (CSI) of cotton and maize were reduced under water stress. A higher level of leaf proline content was observed under severe water-stressed treatments in cotton and maize. RLWC and CSI were highest and leaf proline content was lowest in mild water deficit (ADI at 100% crop evapotranspiration once in three days) irrigation in cotton and maize. The same treatments registered higher values for crop yields, net income and benefit cost ratio for both the crops.

scholarly journals Vegetation of the Witbank Nature Reserve and its importance for conservation of threatened Rocky Highveld Grassland

Koedoe ◽  
1997 ◽  
Vol 40 (2) ◽  
Author(s):  
C.M. Smit ◽  
G.J. Bredenkamp ◽  
N. Van Rooyen ◽  
A.E. Van Wyk ◽  
J.M. Combrinck
Keyword(s):  
Soil Moisture ◽  
Plant Communities ◽  
Nature Reserve ◽  
Soil Depth ◽  
Floristic Composition ◽  
Diversity Indices ◽  
Moisture Gradient ◽  
Negative Effects ◽  
Soil Moisture Gradient ◽  
Great Escarpment

A vegetation survey of the Witbank Nature Reserve, comprising 847 hectares, was conducted. Phytosociological data were used to identify plant communities, as well as to determine alpha and beta diversities. Eleven plant communities were recognised, two of these are subdivided into sub- communities, resulting in 14 vegetation units. These communities represent four main vegetation types, namely grassland, woodland, wetland and disturbed vegetation. Grassland communities have the highest plant diversity and wetland vegetation the lowest. Floristic composition indicates that the vegetation of the Rocky Highveld Grassland has affinities to the grassland and savanna biomes and also to the Afromontane vegetation of the Great Escarpment. An ordination scatter diagram shows the distribution of the 14 plant communities or sub-communities along a soil moisture gradient, as well as along a soil depth/surface rock gradient. The sequence of communities along the soil moisture gradient is used for calculating beta-diversity indices. It is concluded that the relatively small size of the Witbank Nature Reserve is unlikely to have significant negative effects on the phytodiversity of the various plant communities. This nature reserve is therefore of considerable importance in conserving a representative sample of the Rocky Highveld Grassland.

Effect of soil moisture gradient on structure of broad-leaved/Korean pine forest in Changbai Mountain

2004 ◽  
Vol 15 (2) ◽  
pp. 119-123 ◽  
Author(s):  
Wang Yan ◽  
Wang Qing-li ◽  
Dai Li-min ◽  
Wang Miao ◽  
Zhou Li ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Moisture Gradient ◽  
Pine Forest ◽  
Changbai Mountain ◽  
Korean Pine ◽  
Soil Moisture Gradient ◽  
Korean Pine Forest

scholarly journals Do Differences in Latitudinal Distributions of Species and Organelle Haplotypes Reflect Thermal Reaction Norms Within the Emiliania/Gephyrocapsa Complex?

2021 ◽  
Vol 8 ◽  
Author(s):  
Peter von Dassow ◽  
Paula Valentina Muñoz Farías ◽  
Sarah Pinon ◽  
Esther Velasco-Senovilla ◽  
Simon Anguita-Salinas
Keyword(s):  
Local Adaptation ◽  
Coastal Upwelling ◽  
Environmental Gradients ◽  
Reaction Norm ◽  
Emiliania Huxleyi ◽  
Thermal Reaction ◽  
Reaction Norms ◽  
Thermal Niche ◽  
Significant Difference ◽  
The Difference

The cosmopolitan phytoplankter Emiliania huxleyi contrasts with its closest relatives that are restricted to narrower latitudinal bands, making it interesting for exploring how alternative outcomes in phytoplankton range distributions arise. Mitochondrial and chloroplast haplogroups within E. huxleyi are shared with their closest relatives: Some E. huxleyi share organelle haplogroups with Gephyrocapsa parvula and G. ericsonii which inhabit lower latitudes, while other E. huxleyi share organelle haplogroups with G. muellerae, which inhabit high latitudes. We investigated whether the phylogeny of E. huxleyi organelles reflects environmental gradients, focusing on the Southeast Pacific where the different haplogroups and species co-occur. There was a high congruence between mitochondrial and chloroplast haplogroups within E. huxleyi. Haplogroup II of E. huxleyi is negatively associated with cooler less saline waters, compared to haplogroup I, both when analyzed globally and across temporal variability at the small special scale of a center of coastal upwelling at 30° S. A new mitochondrial haplogroup Ib detected in coastal Chile was associated with warmer waters. In an experiment focused on inter-species comparisons, laboratory-determined thermal reaction norms were consistent with latitudinal/thermal distributions of species, with G. oceanica exhibiting warm thermal optima and tolerance and G. muellerae exhibiting cooler thermal optima and tolerances. Emiliania huxleyi haplogroups I and II tended to exhibit a wider thermal niche compared to the other Gephyrocapsa, but no differences among haplogroups within E. huxleyi were found. A second experiment, controlling for local adaptation and time in culture, found a significant difference between E. huxleyi haplogroups. The difference between I and II was of the expected sign, but not the difference between I and Ib. The differences were small (≤1°C) compared to differences reported previously within E. huxleyi by local adaptation and even in-culture evolution. Haplogroup Ib showed a narrower thermal niche. The cosmopolitanism of E. huxleyi might result from both wide-spread generalist phenotypes and specialist phenotypes, as well as a capacity for local adaptation. Thermal reaction norm differences can well explain the species distributions but poorly explain distributions among mitochondrial haplogroups within E. huxleyi. Perhaps organelle haplogroup distributions reflect historical rather than selective processes.

Sign in / Sign up

Export Citation Format

Share Document