Gas exchange characteristics, water use efficiency and osmotic adjustment in relation to heterosis in hot pepper (Capsicum annuum L.) under water stress

Abstract

Two hybrids and parents (hyb MSH-11; IHR 3289
male, IHR 3285 female and hyb ECH-86; IHR 2444 male, IHR
AR 18 female parents) of hot pepper (Capsicum annuum L)
were studied to examine the response of morphological
attributes, net photosynthetic rate (PN), stomatal
conductance (gs) and water use efficiency (WUE) under
control (irrigated) and water stress conditions. Water stress
was imposed at flowering stage under field condition by
withholding the irrigation for a period of 35 days. Both the
hybrids responded differentially to water stress. In general,
the plant height, fruit numbers, fruit fresh weight and total
dry matter (TDM) accumulation were higher in hybs than
their respective parents in control as well as stress
conditions. The fruit bearing and TDM accumulation were
more in hyb MSH-11 compared to the hyb ECH-86. The
hyb ECH-86 had the higher PN compared to parents under
control as well as stress conditions. However, in hyb MSH-
11, there was no definite patter in PN under control but it
was greater than parents under water stress. Though, in
both the hybs PN decreased substantially after 21 days of
stress, the quantum of decrease was more in hyb ECH-86
than hyb MSH-11. Further MSH-11 had shown better
osmotic adjustment (OA) than hyb ECH-86. The higher
WUE of hyb MSH-11 than its parents under control and
stress conditions shows the heterosis for WUE in this
hybrid. WUE was higher in hyb MSH-11 (2.5μ mol CO2/mol
H2O ) as compared to hyb ECH-86 (2.0μ mol CO2/mol H2O)
under stress which may be due to the higher PN in this
hybrid under stress. The heterosis for TDM, PN and WUE
in hyb MSH-11 under stress may be a contributing factor
for better performance of this hyb under stress.