Effects of defoliation on growth of cauliflower

Three experiments were performed with defoliation of young cauliflower plants in the field. The leaves were removed 3–6 weeks after planting and about 65% of the leaf area were removed. After defoliation, several plant processes contributed to compensate for the loss of leaf area. Right after defoliation, the ratio of leaf area to plant weight was strongly decreased. However, during further growth the ratio of leaf area to plant weight was increased in defoliated plants. Together with an increase in net assimilation rate it contributed to the increase in plant relative growth rate after defoliation. Due to higher rates of leaf growth relative to stem growth, the biomass allocation pattern was re-established. Specific leaf area was increased in defoliated plants due to depletion of reserves, and contributed to the restoration of the relationship between leaf area and plant dry weight. Concentrations of non-structural carbohydrates were reduced after defoliation, showing that reserves were mobilised to support re-growth. We found that cauliflower through a number of mechanisms re-established the basic relationships in the plants after damage, and this observation and the estimated relationships can be used for modelling effects of pest damage on crop growth.