Abstract:
is essential for improving productivity and developing high performing cultivars. This
study examined the relationships among chlorophyll content, r,egetative growth
parameters and yield-related traits in six cowpea v'arieties (MICPl, M135, ANKCPI,
WAR\\NI, DHAWALA and BOMBAY) grown under field conditions using a
Randomized Complete Block Design (RCBD) with three replications. Chlorophyll
content was quantified using both SPAD meter readings and spectrophotomeffic
assays u'hile vegetative traits and leld components were recorded at 5 and 7 weeks
after planting. Results revealed clear varietal di{ferences in both ph-vsiological and
yield traits . BOMBAY recorded the highest Chlorophyll values. DHAWALA exhibited
tlre greatest plant hei-eht and canopy spread whereas MICP I showed the smallest
stature but possessed the largest leaf area. Yield performance also differed
significantly with ANKCPI achieving the highest grain yield per plant (39.31* 0.53
g) associated with a superior harvest index despite not having the highest vegetative
vigor. Correlation analysis indicated a weak and negative association between
chlorophyll content and grain yield (r: -0.04) demonstrating that higher chlorophyll
content did not predict final productivity. Stomatal obsen'ations further showed
varietal differences in gas exchange capacity with WAR(/l/l having higher stomatal
density and larger guard cells compaled to the more conservative water-use strategy
of ANKCPI. These findings exhibit substantial physiological and yield diversity
anong the tested cowpea varieties and identi$r ANKCPI, DHAI'\ULA and BOMBAY
as lines of particular interest for future breeding. The findings emphasize that
balanced vegetative gro\,th and efficient biomass allocation rather than maximum
chlorophyll content alone is the key determinants of cowpea yield urder field
conditions in Sri Lanka.
