Periodicity in the development of the root system of young rubber trees (Hevea brasiliensis Müell. Arg.): relationship with shoot development

Abstract

The growth pattern of the root system of young rubber trees (Hevea brasiliensis) was studied in relation to shoot development over a period of 3 months. Temporal and spatial variations in elongation and branching processes were examined for the different root types, by means of root observation boxes. Shoot growth was typically rhythmic. Root development was periodic and related to leaf expansion. Root elongation was depressed during leaf growth, whereas branching was enhanced. Consequently, highly branched areas with vigorous secondary roots alternated along the taproot with poorly branched areas with shorter roots. Root types were not affected to the same degree by shoot competition: during leaf expansion, taproot growth was just depressed but remained continuous, the emergence and elongation rates of secondary roots were significantly affected and the elongation rates of tertiary roots fell to zero. These results were consistent with the hypothesis that root growth is related to competition for assimilates and to the sink strength of the different root types, whereas root branching appeared to be promoted by leaf development.

Effects of excess boron on growth, gas exchange, and boron status of four orange scion–rootstock combinations

“…There were few reports on the combinations of scion-rootstock upon exposure to excess B in citrus plants. However, previous studies have suggested that root architecture could directly affect exploitation efficiency of nutrition and water required for plant growth (Berntson, 1994;Nielsen et al, 1994), while carbohydrate derived from the leaf photosynthesis and phytohormones synthesized in the growing shoots can affect the architecture of the root system and its function (Thaler and Pagès, 1996;Wightman and Thimann, 1980). In our experiment, excess-B treatment may have caused a significant decrease in net photosynthesis (Fig.…”

Effect of ammonium/nitrate ratio on growth and development of avocado plants under hydroponic conditions

“…Also, much of the first growth unit probably relied on the reserves of the scion (both nitrogen and carbohydrate reserves), which may have made the plant less dependent on external N sources, while the second growth unit required uptake and assimilation of external nitrogen, and was affected by nitrogen form. The alternating periodicity of shoot and root development is also a well known phenomenon, particularly in tropical trees (Thaler and Pagès 1996). In this experiment, nitrogen during the first growth unit may have affected the following root development, while the effect on aerial development may have appeared only during the second growth unit.…”

Water extraction and implications on soil moisture sensor placement in the root zone of banana

“…However, Green and Clothier (1995) studied water extraction of kiwifruit vines and observed that root water uptake was more dependent on soil water availability than of thin roots distribution. Yet, there are other studies indicating that the diameter of lateral roots was also a highly variable factor in the soil (Yorke and Sagar, 1970;Cahn et al, 1989;Varney et al, 1993;Jordan et al, 1993;Thaler and Pagès, 1996). In addition, Lecompte et al (2005) report that this variability was a consequence of factors like soil heterogeneity, root system structure, and availability and partitioning of carbon in the roots, but the relative contribution of each of these factors remain largely unknown.…”