Agriculture Reference
In-Depth Information
because of their mutual synergistic relationship, but Ca decreased due to antago-
nistic effect. Uptake of Fe and Cu were positively correlated, while Mn and Zn
negatively correlated with applied B. The deficient state of B resulted in decreased
the leaf N, P, Ca, Mg, Fe, Cu, Zn and B in tomato. On the other hand, excess B
increased the concentration of nutrients with greater significance for K, Mg and Fe
followed by Ca and Mn and in smaller quantity Cu and Zn (Carpena-Artes and
Carpena-Ruiz
1987
).
B toxicity had no consistent effects on the tissue concentration of P, K, Ca, Mg,
Zn, Cu, Fe and Mn for five barley and six wheat cultivars grown in nutrient solution
and no interactions were found among B nutrients and cultivars (Nable
1989
).
Higher levels of applied B significantly depressed the N and enhanced P and K
contents in three cuttings of
Trifolium alexandrinum
(berseem; Pal et al.
1989
).
Singh et al. (
1990
) reported that the concentration of P, Mg and Zn in wheat
increased and Ca, K, Cu, Fe and Mn decreased with increasing B in soil. On the
other hand, an increasing supply of B significantly decreases the uptake of P, K, Ca,
Mg and Mn, while that of Zn, Cu and Fe increased. They concluded that high levels
of applied B had an antagonistic effect on the uptake of nutrients and this could be
due to the toxic effect of B on root cells, resulting in impaired nutrient absorption
processes. Alvarez-Tinaut (
1990
) found positive correlations between B and Fe and
Cu contents of sunflower, suggesting that B could indirectly affect catalase activity
via Fe and Cu. Positive correlations between Zn and B also indicated that B could
indirectly affect the enzyme through modification of the Zn content. Concentra-
tions, total uptake and ratios of certain nutrients in radish top and root change with
differential B supply to nutrient solution (Tariq
1997
). However, this study also
suggested that changes occurring were mainly due to the B effect and partially due
to antagonism between Ca and B. It is clear from the reported literature, that B
interactions, either synergism or/and antagonism, can affect plant nutrition under
both deficiency and toxicity conditions.
With increasing B supply in nutrient medium, leaf content of P became high
(usually younger leaves shows higher P concentration) and there was a minor
decrease in K, Ca and Mg compared to the average concentration for leaves (Furlani
et al.
2003
).
Yang and Gu (
2004
) demonstrated the effect of B on Al toxicity for soybean
seedlings. They showed that high supply of B was found to induce Al toxicity by
significantly increasing growth parameters including root length at 2 mM, and fresh
weight at 5 mM Al for two different cultivars. Similar results have been described
by Hossain and Hossain (
2004
), who confirmed the relationship of B with Al. The
ratio between Ca and B in the plant is sometimes used to identify B deficiency. In
one study, the supply of Ca and B to four maize cultivars considerably improved
shoot dry matter production (Kanwal et al.
2008
).
B is responsible for changes in other nutrients in soil-plant interactions (Tariq
and Mott
2006
). They also showed optimum productivity of radish plants at 0.5 mg
l
1
B supply. Toxic effects confirmed by significant productivity decreases were
found at increased levels of B supply. The amount of B, Zn and Cu in plants was
increased and amount of Fe, Mn and Mo were reduced. Except B, the net uptake of
