Number Of Secondary Roots Research Articles

Types of branching in lateral roots of rice plants

In most crown roots of rice plants, usually, the number of secondary lateral roots (per cm of the crown roots) gradually increases from the base towards the tips, comes up to the maximum, and then decreases with decreasing of the diameter of the crown roots. Many other types of branching, are found, i. e., (1) thin crown roots possess abundant secondary lateral roots especially at the apical part. These roots initiate from the upper units of stem and concentrate near the soil surface4) ; (2) some crown roots are conspicuously thick in diameter at the base, though branching features are the same as the ordinary ones mentioned above; (3) roots possess numerous secondary lateral roots in their basal parts. These roots appear just after transplanting in a paddy field ; (4) a group of aberrant roots, which is characterized by short shape, covered with few lateral roots (Fig. 3. 6-9); (5) roots often showing a shape similar to lion-tail, covered very densely with many thick secondary lateral roots6) (Fig. 3. 12-14); (6) occasionally, faciated secondary lateral roots are found at the base of the crown roots (Fig. 3. 15-19). These roots possess many thick secondary lateral roots and weak ones which can not emerge outside the epidermis of the crown roots; and (7) another type of roots seemed to have grown in upland field, is found (Fig. 3. 20-21).

‘Lyamungu dieback’ of arabica coffee in Tanganyika

SUMMARYThe symptoms of Lyamungu dieback on foliage, branches and roots are described and compared with those of other diebacks of coffee; retention of the dead leaves is a distinguishing symptom. The severity of the disorder is related to the stage of maturity and size of the crop.The degree of brown flecking of the xylem of the roots reflects the severity of the attack but is not determined by infection by Fusarium oxysporurn. The number and weight of secondary roots is reduced in the first year that the coffee is affected and further reduced if the trees survive into the succeeding year.Lyamungu dieback has caused serious losses at the Coffee Research Station, Lyamungu, since 1956, and is randomly distributed on estates in northern Tanganyika.The disorder is associated with heavy cropping and influenced by environment and cultural management. In experimental plots its effects were diminished by artificial shading (which reduced the crop) and by heavy nitrogenous manuring.

Studies on the Relationship between Growth of Roots in Successive Nodes of Wheat and Corn and Soil Conditions

The present study was undertaken to investigate, according to the previous paper, how to change the development of branching, curvatures and the shooting angles of roots in successive nodes when wheat and corn were planted under the different kinds of soil and manure. The following results were obtained: 1. The height and number of tillers were greater in compost plot and heavy fertilized plot and were inferior in clay plot. 2. The curvature and branching of rots were more developed in compost plot and sand plot but were meagerest in clay plot (Fig. 1, 2). Therefore number and length of secondary and tertiary roots were superior in compost plot and sand plot than in clay plot. 3. In compost plot the rot angles were large and elongated horizontally, but in sand plot the angles were smaller (Fig. 3, 4). From these results, it can be said that the root angle is influenced by soil conditions and there is a tendency that the root angle is larger when the plant is more grown.

On the Development of Branch-roots on Successive Nodes of Rice Plants

In the present experiment the author wanted to obtain some further understandings on the relations existing between development of the branch-roots and emergence of the leaves, and on the growth mode of the branch-roots under lowland conditions in comparison with that under upland conditions. 1. The author noticed two kinds of branch-roots (bigger and smaller). Diameter of the smaller one was 0.035∼0.075 mm and that of the bigger 0.25∼0.30 mm. The bigger branch-roots branched further but the smaller didn't. 2. Development of the primary, the secondary, the tertiary and the fourthly branch-roots etc. on successive nodes proceeded at the same pace as the period of leaf emergence in the similar way as has been seen in wheat plants. 3. The roots under upland conditions made many branches waving conspicuously, and the number of big secondary roots (mentioned at 1) was twice to three times that under lowland conditions. And branching was repeated so much as to make even fourth order branch-roots under upland conditions, while it did not go further than to have tertiary branch-roots under lowland conditions. Mat roots developed vigorously at the nodes higher than the 8th node under lowland conditions, but they were not observed under upland conditions. Under lowland conditions the root maintain its activity for a shorter period becoming to decrepitude earlier than upland conditions.

A Comparative Study of the Number and Length of Roots Produced in Nineteen Angiosperm Species

1. Quantitative studies of the roots of nineteen species of plants in fourteen different angiosperm families were made. Results indicating the total number of roots and root lengths are presented in tabular form. 2. Tertiary roots produced about one quaternary root per centimeter of length in most of the plants examined; however, the number of secondary and tertiary roots developing from main and secondaries, respectively, varied considerably. 3. Variation in number of roots and root length results from differences in size of plant, age, inheritable stability, and competition with other plants. Generally, plants show a compensating factor in root growth; when restricted in one category, another root division or two will exhibit much greater growth.

INFLUENCE OF INDOLE ACETIC, INDOLE BUTYRIC, AND NAPHTHALENE ACETIC ACIDS ON ROOTS OF LUPINUS ALBUS SEEDLINGS

THAT A voluminous literature has already been accumulated concerning auxins, or plant hormones, and various plant growth-promoting chemicals may be gathered from the work of Boysen-Jensen (1936) on this subject. Careful investigation has been made of the action of growth-stimulating chemicals on stems, shoots, and roots of various plants, and two interesting conclusions have been drawn therefrom. The first is that the growth of stems and shoots of various plants and the formation of roots in cuttings is remarkably stimulated by application of various chemicals, a finding of considerable practical value in horticultural propagation, as the work of Went (1929), Thimann (1934), Koepfli (1935), and their coworkers and the researches of Zimmerman, Hitchcock, and Wilcoxon (1935,1936) of the Boyce Thompson Institute for Plant Research have strikingly demonstrated. The second remarkable finding is the curious difference between the effect of growthstimulating chemicals and auxins on stems and their action on the growth of primary roots, for it has been asserted by most of those writing on this subject that while these chemicals promote the elongation of stems and shoots, they inhibit growth of primary roots. This was first shown by Nielsen in 1930 and later by Kogl, Haagen-Smit, and Erxleben (1934), Hitchcock and Zimmerman (1936) and others. This extraordinary finding has given rise to much speculation and consderable experimentation in an endeavor to elucidate the mechanism of plant-hormone action on the two different tissues. Thus Thimann (1936) concluded that the magnitude of auxin effect depends largely upon the direction in which it is applied. Marmer (1937), studying the effects of growth-stimulating chemicals on wheat seedlings, found that while the primary root is inhibited, the number of secondary roots is increased and there is change in effectiveness of these compounds at an alkaline pH. Robbins and Jackson (1937) on the basis of their experiments with growth-promoting drugs applied in the form of an ointment with a lanolin base concluded that these chemicals increase the extensibility of the stem cells and decrease the extensibility of the root cells and thus explain the difference in the action of auxin on the respective tissues. Leonian and Lilly (1937) concluded from their studies on the effect of plant-growth-promoting hormones on algae and on roots and shoots of germinated corn that indole acetic acid (heteroauxin) is to be regarded as a growth-inhibiting rather than a growthpromoting substance. In a recent paper by Amlong (1936), however, the question concerning the action on roots of growth-promoting substances is answered