Influence of Water Stress and Rhizobial Inoculation on the Accumulation of Chlorophyll in Phaseolus vulgaris (L.) Cultivars

Aims: To assess the effect of water stress periods and rhizobial inoculation in five (5) P. vulgaris (L.) cultivars.

Study Design: The experiment was designed in split-split plot and replicated 3 (three) times.

Place and Duration of Study: The field experiment was carried out for two consecutive seasons in the year 2014 and 2015, whereas, the screen house experiment was planted in a single season in the year 2016 at the Agricultural Seed Agency (ASA) farm in Arusha-Tanzania.

Methodology: The experiment consisted of 2 levels of rhizobia (with and without inoculation), two stress levels (with and without water stress) and five cultivars of P. vulgaris (L.) (KAT B9, KAT B1, F9 Kidney Selection, F8 Drought line and JESCA). The stress period of 10 days were imposed at vegetative and flowering stages of plant growth by not irrigating. Chlorophyll was extracted using dimethyl sulphoxide (DMSO). Absorbance values were read at 645 nm and 663 nm by 2800 UV/Vis Spectrophotometer.

Results: Results indicated that leaf chlorophyll content was higher in rhizobial inoculated and non-stressed water treatments. Leaf chlorophyll content was significantly higher in varieties 3(F9 Kidney Selection) and 2(KAT B1) as compared with varieties 1(KAT B9), 4(F8 Drought line) and 5(JESCA). Significant interactions were observed between rhizobial inoculation x water stress and bean varieties.

Conclusion: Rhizobial inoculation and adequate water supply significantly improved leaf chlorophyll content in the tested cultivars.