Evaluation of the morpho- anatomical and physiological features of phosphorus- deficient-grown seedlings of tomato (Lycopersicon esculentum Miller)

Date

4-2002

Degree

Bachelor of Science in Biology

Major Course

Major in Cell Biology

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Arcelia A. Alejar

Abstract

The morpho-anatomical and physiological features of tomato seedlings cv Alariku grown for 15 days in phosphorus-deficient Hoagland's culture solution were evaluated. Phosphorus deficiency symptoms were successfully induced and were observed as early as five days after treatment and became more pronounced until the I5th day. Biomass production was significantly reduced in shoots but not in roots resulting in a 100% increase in root:shoot ratio of dry weight. Leaf protein was decreased significantly by three-fold in contrast to high detectable starch in leaves. Phosphorus-deficient plants were stunted, had greener, smaller and fewer number of leaves with purple stem. The darker green leaves of phosphorus-deficient seedlings were attributed to the two-fold increase in amount of chlorophyll per unit leaf area. It was also evidenced by the longer, much closer palisade parenchyma and greater number of spongy parenchyma cells. The relative sizes of the chloroplasts were found to be the same for both healthy and phosphorus-deficient leaves. The purple coloration of the stem was due to the obtained higher amount of anthocyanin pigment. Roots were longer and finer, exhibited more laterals and have profuse root hairs. Cytological examination of the root tip revealed that meristem size and mitotic activity were significantly reduced by 20% and 62%, respectively. Earlier differentiation of root epidermal cells, together with the observed numerous root hairs induced at low phosphorus supply can explain the unaffected ash content of not only the roots but also the shoots. The significant increase in cation exchange capacity of the roots by 25% under low phosphorus likewise contributed to the uptake of other cations. Moreover, roots exhibited a significant increase in phosphatase activity. The above results confirmed previous reports on the phenotypic plasticity of stressed plants under phosphorus deficiency. However, the present findings on the characterization of the root apex were the first report regarding acclimation of roots to phosphorus deficiency.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

Thesis

Document Type

Thesis

This document is currently not available here.

Share

COinS