Abstract: Hot pepper variety‘Huaxi’was used to study the effects of Ca^{2 +} on the growth and enzyme activities related to respiratory metabolism of hot pepper seedling root at different time (0, 3, 6, 9 and 12 d)after flood stress. The results showed that exogenous Ca2 + could significantly reduce damage under flood stress. The root growth of hot pepper could be improved, and total length, total surface area, total volume,root hair number and root diameter were significantly larger than those of flood stress. Exogenous Ca^{2 +} increased root activity, decreased electrolyte leakage, enhanced ADH activity, reduced LDH activity, compared to those of flood stress, which avoided the accumulation of lactic acid and acetaldehyde, kep t higherMDH and
SDH activities and a certain level of aerobic respiration. Exogenous Ca^{2 +} might alleviate damage to the seedling root of hot pepper under flood stress by regulating respiratory metabolism.

Key words: pepper, Ca^{2 +}, flood stress, root, growth, respiratory metabolism