The shoot dry weights of 81-day-old wheat plants
grown in soil culture were significantly affected by soil sterilization as well as Zn and P applications, but no
significant interactions were observed (Table 1). On
average, soil sterilization and high soil Zn increased
the shoot biomass by 14 % and 7 %, respectively.
With respect to the low-P treatment, the medium-P
treatment enhanced the shoot biomass production by
50 %, but the high-P application did not provide any
additional benefit. As can be seen in Fig. 1, the general
condition and visual appearance of the plants varied
greatly according to the treatments at this stage. Under
non-autoclaved soil conditions (Fig. 1a), when the Zn
supply was low, increasing P supply resulted in reduced
plant height, delayed development and caused more
severe leaf symptoms including chlorosis and necrosis.
In contrast, when the Zn supply was high, higher P
applications increased plant height and overall vigor.
Similar trends were also observed in autoclaved soil
(Fig. 1b), but the effects were less pronounced. In terms
of grain yield, the interactive effects of soil Zn and P
applications were significant at maturity (Table 1). They
markedly augmented the positive effects of each other
on grain yield. At low P, the grain yield did not respond
to high Zn, whereas at high P, plants produced 50 %
more grains by weight in response to high Zn.