Responses of mango (Mangifera indica L.) root stock seedlings to water stress

Abstract

The present studies were aimed at investigating the effect of different watering regimes on the gas exchange parameters (stomatal conductance, CO₂ assimilation and transpiration rates) and chlorophyll content of young Mango (Mangifera indica) rootstock seedlings. The hypothesis was that different levels of water deficit affect the gas exchange parameters and chlorophyll content of the mango rootstock seedlings. Six-month-old Mango (Mangifera indica L.) rootstock seedlings were grown in polythene pots in a greenhouse at Maseno University, Kenya from December 2003 to March 2004 and subjects to four different watering regimes (namely daily, twice in a week, once in a week and once in two weeks). These treatments were in a Completely Randomized Design (CRD) with six replications. The parameters determined were stomatal conductance, transpiration rate, CO₂ assimilation rate and intercellular CO₂ concentration. All the gas exchange parameters were determined by infra Red Gas Analyser (PP systems). The results showed that increasing water stress reduced the physiological parameters particularly at the later days of plant growth due to stomatal and non-stomatal factors. Leaf chlorophyll content however was slightly increased since the chlorophyll pigments may have been resistant to dehydration. It is concluded that increase in water stress (increasing level of water deficit) reduces the gas exchange parameters of mango (Mangifera i