Abnormal stomatal behaviour and leaf anatomy in Capsicum annuum, scabrous diminutive, a wilty mutant of pepper

An attempt is made to explain the tendency to excessive wilting in scabrous diminutive, a pepper mutant. For this, mutant and normal plants were compared with respect to leaf anatomy, transpiration of whole plants and detached drying leaves, density and opening of stomata, staining of potassium in epidermal cells and root pressure.A much greater proportion of intracellular space was found in the mutant leaf which contains fewer and smaller mesophyll cells than the normal plant. The anticlinal walls of the epidermis of the mutant leaf were almost straight whereas those of the normal were wavy. Transpiration per unit leaf area of whole plants, percentage of stomata open both day and night, and water loss from detached drying leaves were all higher in the mutant. Potassium staining in guard cells was similar in both plant types, slightly less in darkness and marginally higher in light. The subsidiary cells of normal leaves did not stain at all, but those of the mutant leaves stained heavily in both light and darkness. Root pressure was lower in the mutant.Possible explanations for the tendency of the pepper mutant to wilt are discussed.