Photosynthesis, water relations, and leaf morphology of xeric versus mesic Quercusrubra ecotypes in central Pennsylvania in relation to moisture stress: Discussion of sample size, sampling, and statistical analyses in a physiological genetics paper

1994 ◽  
Vol 24 (3) ◽  
pp. 642-643 ◽  
Author(s):  
J.R. Seiler ◽  
K.H. Johnsen
Keyword(s):  
Sample Size ◽  
Water Relations ◽  
Leaf Morphology ◽  
Moisture Stress ◽  
Statistical Analyses ◽  
Central Pennsylvania

not available

Photosynthesis, water relations, and leaf morphology of xeric versus mesic Quercusrubra ecotypes in central Pennsylvania in relation to moisture stress

1992 ◽  
Vol 22 (9) ◽  
pp. 1402-1407 ◽  
Author(s):  
Mark E. Kubiske ◽  
Marc D. Abrams
Keyword(s):  
Water Relations ◽  
Leaf Morphology ◽  
Photosynthetic Apparatus ◽  
Morphological Characteristics ◽  
Net Photosynthesis ◽  
Moisture Stress ◽  
Tissue Water ◽  
Central Pennsylvania ◽  
Relative Water ◽  
Mesic Site

Differences in photosynthesis and water relations during drought, and in leaf morphology, were evaluated in 1-year-old greenhouse-grown Quercusrubra L. seedlings from neighboring mesic and xeric sites in central Pennsylvania, U.S.A. Xeric seedlings had higher photosynthetic rates and stomatal conductance to water vapor than mesic seedlings during well-watered conditions. During a drought cycle, xeric seedlings maintained positive net photosynthesis at significantly lower predawn leaf water potential and relative water content. Mesic seedlings exhibited greater intrasource variation in gas exchange during drought, which may be related to reduced selection pressure for drought tolerance characteristics on the mesic site or to gene flow from the adjacent, upslope xeric site. Nonstomatal limitations to photosynthesis increased during drought and accounted for 98% of the reduction in photosynthesis as both sources approached incipient wilting. Xeric seedlings exhibited less nonstomatal inhibition of photosynthesis during early and midstages of drought, suggesting a greater tolerance of the photosynthetic apparatus for tissue water deficit. Xeric seedlings also exhibited the expected leaf morphological characteristics, which included smaller leaf area and greater leaf thickness and specific leaf mass. These results indicate that Q. rubra growing on adjacent sites in central Pennsylvania exhibit ecotypic differences in ecophysiology that are consistent with site moisture conditions.

scholarly journals Cavalier Use of Inferential Statistics Is a Major Source of False and Irreproducible Scientific Findings

Mathematics ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 603
Author(s):  
Leonid Hanin
Keyword(s):  
Sample Size ◽  
Gaussian Approximation ◽  
Statistical Significance ◽  
Statistical Analyses ◽  
Random Sample Size ◽  
P Values ◽  
The Central Limit Theorem ◽  
Fixed Sample ◽  
Large Numbers ◽  
Significance Levels

I uncover previously underappreciated systematic sources of false and irreproducible results in natural, biomedical and social sciences that are rooted in statistical methodology. They include the inevitably occurring deviations from basic assumptions behind statistical analyses and the use of various approximations. I show through a number of examples that (a) arbitrarily small deviations from distributional homogeneity can lead to arbitrarily large deviations in the outcomes of statistical analyses; (b) samples of random size may violate the Law of Large Numbers and thus are generally unsuitable for conventional statistical inference; (c) the same is true, in particular, when random sample size and observations are stochastically dependent; and (d) the use of the Gaussian approximation based on the Central Limit Theorem has dramatic implications for p-values and statistical significance essentially making pursuit of small significance levels and p-values for a fixed sample size meaningless. The latter is proven rigorously in the case of one-sided Z test. This article could serve as a cautionary guidance to scientists and practitioners employing statistical methods in their work.

scholarly journals EFFECTS OF SOIL MOISTURE STRESS ON THE WATER RELATIONS AND WATER USE OF GROUNDNUT STANDS

1985 ◽  
Vol 100 (3) ◽  
pp. 313-328 ◽  
Author(s):  
C. R. BLACK ◽  
D.-Y. TANG ◽  
C. K. ONG ◽  
A. SOLON ◽  
L. P. SIMMONDS
Keyword(s):  
Soil Moisture ◽  
Water Use ◽  
Water Relations ◽  
Moisture Stress ◽  
Soil Moisture Stress

HETEROPHYLLY IN HIPPURIS, A PROBLEM IN IDENTIFICATION

1961 ◽  
Vol 39 (5) ◽  
pp. 1099-1116 ◽  
Author(s):  
Margaret E. McCully ◽  
Hugh M. Dale
Keyword(s):  
Water Relations ◽  
Leaf Morphology ◽  
Experimental Studies ◽  
Main Criterion ◽  
Leaf Form ◽  
Diverse Origin ◽  
Great Uniformity ◽  
Further Development ◽  
Foliar Morphology

Although the primordia of all types of leaves in Hippuris show no distinguishing characteristics until they are 50 microns long, their further development is strongly influenced by their environment. At maturity they can, for convenience, be thought of as belonging to one of five types, or some intermediate of these types. The five types of leaves are: rhizome, juvenile aquatic, adult aquatic, juvenile aerial, and adult aerial. Field and experimental studies indicate that the leaf form in Hippuris is influenced by light and the water relations between the plant and its environment. There is great uniformity of foliar morphology on plants from stocks of diverse origin when grown under uniform conditions, and there is wide diversity of foliar morphology on plants of the same stock material when grown under different environments in the laboratory. Thus the taxonomic subdivision of genus Hippuris into species, varieties, and forms using leaf morphology as the main criterion appears questionable.

Growth, Water Relations, and Nutritive Value of Pasture Species Mixtures under Moisture Stress

Crop Science ◽  
2004 ◽  
Vol 44 (4) ◽  
pp. 1361-1369 ◽  
Author(s):  
R. Howard Skinner ◽  
David L. Gustine ◽  
Matt A. Sanderson
Keyword(s):  
Water Relations ◽  
Nutritive Value ◽  
Moisture Stress ◽  
Species Mixtures

Studies of the water relations of crop plants grown under natural rainfall in northern Australia.

1955 ◽  
Vol 6 (4) ◽  
pp. 365 ◽  
Author(s):  
RO Slatyer
Keyword(s):  
Soil Moisture ◽  
Water Relations ◽  
Internal Control ◽  
Moisture Stress ◽  
Grain Sorghum ◽  
Atmospheric Conditions ◽  
Soil Moisture Stress ◽  
Natural Rainfall ◽  
Dry Conditions ◽  
High Level

Studies of the water relations of cotton, peanuts, and grain sorghum were made at Katherine, N.T., on crops grown under natural rainfall during the 1952-53 rainfall season. In the early part of this season, rainfall was more or less normal and little evidence of stress was seen in the plants. The latter part, however, was abnormally dry and resulted in the appearance of severe water stress symptoms in all crops. The water balance of the plants through the season was followed using Weatherley's (1950) "relative turgidity" technique of leaf turgor measurement. In each crop the relative turgidity level was maintained at a fairly high level until the onset of dry conditions, when a progressive decline commenced. This decline, although continuous, appeared to be in two stages. It was felt that the lag of absorption behind transpiration which resulted in loss of turgor was initially due to the rapid rise in transpiration, which followed the increase in atmospheric aridity with the onset of the dry period. As atmospheric conditions became more static, the continued decline in turgor was attributed primarily to the influence of soil moisture stress, in limiting absorption. Of the three crops, grain sorghum appeared to have the best-developed root system and also the most effective internal control over transpiration. Cotton appeared to be least well equipped in these respects. These features were reflected in generally higher turgor levels in grain sorghum than in other crops, and in a slower rate of decrease in turgor with the onset of dry weather. This decrease was particularly rapid in cotton. This relative resistance to turgor loss was in turn reflected in growth rate reductions in cotton as soon as soil moisture stress appeared, but not in grain sorghum until severe soil moisture stress was evident. The peanut responses throughout appeared intermediate between those of the other two crops.

Water Relations and Carbon‐14 Assimilation of Cotton with Different Leaf Morphology 1

Crop Science ◽  
1980 ◽  
Vol 20 (4) ◽  
pp. 421-426 ◽  
Author(s):  
E. Karami ◽  
D. R. Krieg ◽  
J. E. Quisenberry
Keyword(s):  
Water Relations ◽  
Leaf Morphology ◽  
Carbon 14
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