Promotive effect of 5-aminolevulinic acid on growth, yield and gas exchange capacity of barley (hordeum vulgare l.) grown under different irrigation regimes

Abstract

The effect of ALA on growth, yield and gas exchange capacity of barley (Hordiun vulagare) cv. Gesto grown under three water regimes was evaluated. Barley was irrigated every 7, 14 and 21 days. ALA was applied as foliar spray at 25, 50 and 100 ppm as well as control. Irrigation interval of 21 days significantly reduced grain and straw yields/ha and this reduction was attributed to the reduction in plant height, spike length, number of grains/spike and weight of grains/spike. ALA spray significantly increased grain yield, particularly under 50 and 100 ppm. This increase was accompanying with an increase in plant height, spike length, number of grains/spike and weight of grains/spike. The high grain yield was noticed under 7 days interval and spraying with 50 or 100 ppm ALA. Net photosynthesis (NP), stomatal conductance (gs), transpiration rate (T), mesophyll conductance and intercellular CO2 concentration were significantly reduced with increasing irrigation intervals, while the opposite was noticed in chlorophyll content. ALA did not significantly affect NP, T, Ci and chlorophyll content, while gm and gs was significantly increased with increasing ALA concentration. However, NP was increased by 24.3% under 100 ppm ALA compared with the control. The highest NP and gs appeared under 7 days irrigation intervals and 50 and 100 ppm ALA. Promotive effects on barley yield were clearly appeared under 7 and 14 days irrigation intervals.