Comparison Of Roots Research Articles

Early events in geotropism of seedling shoots.

Developments during the first ten minutes of geotropic stimulation in plant seedling shoots are reviewed. Topics include induction and curvature; early processes; the relationship between auxin, electric field, calcium, and differential growth; gravity reception leading to Went-Cholodny transport; and comparison of root and shoot. Early processes reviewed are sedimentation of amyloplasts, release of ethylene, rise of electrical and auxin asymmetry, redistribution of calcium, asymmetric vascular transport, increase in tendency to deposit callose, and simulation of putative exocytotic voltage transients.

Comparison of root and root hair growth in solution and soil culture

Abstract Aerated solution culture is frequently used for studying plant growth. Few comparisons have been made of root growth in solution with that found in soil. The objective of this study was to compare root growth and root hair development in these two mediums. Corn (Zea mays L.) grown in aerated solution at two temperatures (18 and 25°C) and three P concentrations (2, 10, and 500 μmol L‐1) was compared with that in three soils, Raub (Aquic Argiudoll) and two Chalmers (Typic Haplaquoll) silt loams, in a controlled climate chamber over 21d. Corn plant weight and root growth were similar in solution culture and Raub soil when grown at an air and soil temperature of 18°C. At 25°C both yield and root growth were greater in Raub soil, even though P uptake by corn was 7‐fold greater in solution culture. The same difference was found when corn grown at 25°C in solution culture at 3 different P concentrations was compared with that grown in Chalmers soil at two P levels. Percentage of total root length with root hairs, root length and density and consequently root surface area, were all greater in the Chalmers soil than in solution culture. An increase in soil P, resulted in a decrease in root hair growth. No such relationship was found in solution culture. Although the recovery and measurement of plant roots and root hairs is more convenient in solution culture, results from this study indicate that the usefulness of solution culture for determining those factors which control root growth and root hair development in soil is limited.

COMPARISON OF TESTS CHARACTERIZING VARIETIES OF BARLEY AND WHEAT FOR MOISTURE STRESS RESISTANCE

The tiller survival test was used to characterize eight cultivars of wheat (seven of Triticum aestivum L. and one of Triticum durum Des. F.), and seven cultivars of barley (four of which were Hordeum vulgare L. and three Hordeum distichon L.) for moisture stress resistance. Several avoidance and tolerance tests were then assessed for their effectiveness in characterizing the cultivars for moisture stress resistance in relation to the survival test. Of the avoidance tests, visual wilting correlated well with tiller survival but the water loss from leaves and stomatal diffusion resistance tests did not. Of the tolerance tests, root weight under moisture stress showed a good relationship with survival; root weight without moisture stress correlated well with survival for wheat and somewhat less for barley. A comparison of root and leaf weight in two soils differing in moisture-holding ability was useful but less correlated with survival. An unsatisfactory tolerance test was germination in mannitol as there was no correlation in rankings with drought survival. Two semi-dwarf wheat cultivars, Pitic and Fielder, and the two-rowed barley cultivars Nordal and Volla demonstrated the greatest moisture stress resistance. This study of avoidance and tolerance tests leads us to the conclusion that no one test, used singularly, has sufficient reliability to determine overall cultivar drought response in wheat and barley. At least one test measuring avoidance and one measuring tolerance should be used.

A Comparison of Root- and Shoot-wood Development in Conifer Seedlings

Tracheid diameter, wall thickness, and wall area per tracheid increased towards the root tip in first-year seedlings of Picea sitchensis and Pinns sylvestris ; this is shown to be associated with differences in duration of the expansion and wall thickening phases of tracheid development. Transfer to short days produces a similar response throughout the plant, tracheid diameter and wall thickness decreasing shortly after transfer, due to a decline in rate of development. These data are discussed in relation to growth-regulator gradients likely to exist between root and shoot. It is pointed out that though effects of growth regulators on tracheid dimensions are well documented, it has yet to be established whether this is due to their regulation of the rate or of the duration of development.

Physiological Studies with Heavy Water. II. Germination and Growth Inhibition of Barley by D2O

AbstractSeed germination and barley seedling growth in various D2O concentrations have been studied. It was observed that the emergence of root and shoot was delayed, there being greater delay in shoot than in root emergence. A complete block was observed in germination in pure D2O and the germination rate was slowed down significantly in lower concentrations.An initial germination delay by different D2O concentrations seemed to cause a subsequent retardation in the growth measured as shoot and root length. A comparison of root and shoot length with their respective dry weights suggested that the growth by cell division/elongation might have been affected more than the transport of food materials from the endosperm to the embryo.Analysis of the total sugars of the endosperm and the embryo at 8 hour intervals showed that while the hydrolysis of starch to sugars was progressively decreased by increasing D2O concentrations, the transport rate from endosperm to embryo showed a sharp inhibition in 50% D2O and above. This indicated that the inhibition in the transport of materials, besides less hydrolysis of reserve food materials, may also be a causal factor of germination and growth inhibition in D2O.

Microscopic Structure of the Wool Fiber

An investigation was undertaken to obtain information con cerning the fine details of structure of wool fibers and especially of their constituent scale and cortical cells. Treatment of chemi cally modified wool with the enzyme, pepsin, was found to be an excellent method for releasing individual cells for such studies. It is shown by microdissection that the striated appearance of the cortical cells is due to the presence of many fibrils which can be separated with microneedles. Near the center of each cell is a nucleus which has a granular structure. Between crossed nicols, the fibrillar part of the cortical cells appears birefringent, whereas the nucleus does not. The scales show little internal organization such as exhibited by the cortical cells. When examined with crossed nicols they appear nonbirefringent. Unlike the cells of the cortex, the scales are not easily separated by treatment with enzymes, but remain attached to each other in a manner comparable to the arrangement of shingles on a roof. A comparison of root and shaft of the fiber reveals numerous differences in reaction to microchemical color tests, as well as differences in cellular structure. The root, for example, gives a positive test for sulfhydryl groups whereas the shaft gives a nega tive test. Similarly, the shaft appears birefringent whereas the root does not. These and other observations clearly indicate that as the cells of the root emerge into the shaft a number of physical and chemical changes take place simultaneously. When wool is placed in chlorine water bubbles arise on the surface of the fibers (Allwörden reaction). Evidence is presented in support of the viewpoint that these bubbles arise solely from the scales and that their formation is associated with the reaction of the chlorine with disulfide groups of the cystine in the scales.

A Comparison of Roots of Southern Shortleaf Pine in Three Soils

In the field of forest ecology a problem exists in correlating site values, or site indices, with the features of soils that are influential in the determination of the site indices. Further, of interest and value, is knowledge of the gross morphology of the root system, whose character is influenced greatly by the features of the soil, not disregarding, of course, the inherent tendencies of the plant itself. It is apparent that information on the performance of roots of given species, in different soils affording certain site values, would promote an understanding of the site requirements or preferences of these species. It is the purpose of this study to compare, in a quantitative way, the root system of southern shortleaf pine, Pinus echinata Miller, in three Arkansas soils of known site value for the species.

Comparison of Root and Top Development in Varieties of Strawberry

Comparison of Root and Top Development in Varieties of Strawberry