标题：Net Carbon Dioxide Assimilation Rate, Stomatal Conductance, Intercellular Carbon and Carbon Isotope Discrimination in Eight Cultivars of Rice Treated With Fungicide Baan
摘要：Eight cultivars of rice, namely Thanu, B.R.2655, MTU1001, MTU1010, IR30864, IET7575, KRH2 and KMRwere treated with different concentrations of the fungicide BAAN. It is a systemic fungicide used for controllingof blast disease of rice caused by Pyricularia oryzae. The main composition is 79% sodium lauryl sulphate.The fungicide is used both for seed treatment and for foliar spray (2g/L). Gas exchange traits such as netCO 2 assimilation rate (A), stomatal conductance (gs) and intercellular carbon concentration (Ci) weremeasured using portable photosynthetic systems (IRGA-Infrared gas analyser LICOR-6400 and CIRAS-1).Carbon isotope discrimination was measured using Isotope Ratio Mass Spectrophotometer (IRMS). The 3 rdtop fully expanded leaf from the apex was clamped to the leaf chamber and the observations were recordedwhen A, gs and Ci reached stable value. All gas exchange parameters were recorded between 9 a.m. to 12noon on bright sunny day. Pearson’s correlation coefficient was measured to derive significant findings.Assimilation rates were significant in cultivars like Thanu and IR30864. Changes in assimilation rates wereproportional to changes in stomatal conductance. Cultivar Thanu had lowest rates of CID while it wassignificantly high in cultivar IR30864. A strong correlation exists between assimilation rate and stomatalconductance in all the cultivars studied. Incidence of disease was low during the study period. The CCAanalysis helps in conferring the effects of fungicide Baan on the rice cultivars.
