Effects of NaCl on Meristem Size and Proximity of Root Hairs to the Root Tips in Triticum aestivum (cvs. Lyallpur-73, Pak-81 and Lu-26-S)

Abstract

Seedings of Triticum aestivum cvs. Lyallpur-73, Pak-81 and Lu-26-S were grown in solution culture at varying concentration of NaCl for 8 days. Increasing concentrations of NaCl reduced the size of apical meristem and caused the most distal root hair to form closer to the root tip in all the cultivars. Although the position of the first root hair from the root cap boundary was reduced by salinity, yet there were comparatively little differences between these Pakistani Wheat cultivars in response to NaCl, thus in these studies the relative positions of root hairs is not a good discriminating character for assessing the salt tolerance.Keywords: Triticum aestivum, cultivar, NaCl, Root hair, Root cap Introduction An inhibitory effect of toxic metals such as zine on root growth is well documented (Woolhouse, 1983) indeed comparisons of root growth in solutions containing various concentrations of metals with that in control solutions is a long-established method for determining the metal tolerance of plants (Wilkins, 1978) and both interspecific and intraspecific variation in zinc tolerance has been demonstrated. There is however, very little published information on the physiological basis of the inhibition of root growth by zinc. Considerable work have been done on different aspects of salinity yet limited information is available on specific affects of varying salt concentration on plant physiological processes. Root growth which is an integrated process involving cell division, cell extension and cell differentiation, in particular, we know little about the effects of salinity in the root meristem. As an understanding of physiology of the salt tolerance of plants is important for an effective approach to the salinity problems. To understand the mechanisms of salt tolerance control of Pakistani indigenous cultivars would be extremely valuable to overcome the salinity problem in Pakistan, by the development of salt resistance crops. Considerable work has already been done on the chosen Pakistani cultivars, instead of selecting altogether new cultivars, it was considered more useful to investigate these available Pakistani wheat cultivars. Furthermore, the wide genotypic variations between salt tolerant and salt sensitive cultivars, in respect to a number of pertinent physiological and biochemical parameters, have drawn attention to gain insight of the mechanism of salt tolerance by provision of interspecific variability for salt tolerance. Here some effects of NaCl on the size of meristem and relative positions of the first visible signs of the formation of roots hairs are reported.

Morphological and anatomical effects of crude oil on Pistia stratiotes

“…For example, Ghavzan et al (2006) demonstrated that occurrence of Pistia stratiotes L. was associated with high pollution rates in water bodies, while Niaz and Rasul (1998) showed that Pistia stratiotes L. and Eichhornia crassipes could be used as biological indicators in aquatic habitats if the nature of the polluting salt was known. When exposed to salt shocks, Pistia stratiotes L. showed disturbances in cell size and number in the meristematic region, which resulted in a suppressed growth of the plant (Hanif and Daves 1998). It has been shown to present differential accumulation and tolerance levels for different metals at similar treatment condition coupled with trace element accumulation in tissues, and the bio-concentration factors were proportional to the initial concentration of individual metals in the growth medium and duration of exposure (Odjeigba and Fasidi 2004).…”