Determination of diurnal leaf gas exchange for drip-irrigated kenaf plant in sub-humid climatic conditions

Abstract

Kenaf stands out as an important fiber source in the industry with its 4000-year history. Physiological properties have a great effect on the development process of kenaf. Physiological properties are significantly affected by seasonal air temperature changes and precipitation, as well as fluctuations during the day. The main reason for these fluctuations is seen as instant changes in environmental factors. In this study, it was aimed to determine the hourly changes of leaf gas exchange parameters of drip-irrigated kenaf plant and to examine the relationships between these parameters. Field experiment was conducted in Bursa, Turkey, which has sub-humid climatic conditions. For this purpose, net photosynthesis rate (A), stomatal conductivity (gs), intercellular CO2 concentration (Ci) and transpiration rate ( E) measurements were carried out on 18th September 2019 and 26th September 2020, between 08:00 h and 18:00 h. As a result of the study, while it was determined that A, gs, Ci and E parameters varied between 14.75-23.67 mu mol CO2 m(-2) s(-1), 0.23- 0.74 mol H (2) O m(-2) s(-1), 243-331 mu mol CO2 mol air(-1) and 2.67-7.37 mmol H (2) O m(-2) s(-1), respectively in 2019, they varied between 13.97-22.30 mu mol CO2 m(-2) s(-1), 0.29-0.58 mol H2O m(-2) s(-1), 217-278 mu mol CO2 mol air(-1) and 6.3-14.7 mmol H2O m(-2) s(-1), respectively in 2020. Different measurement times had significant effects on all parameters at the p<0.01 level for both years. As a result of the evaluation of the relationships between gas exchange parameters, it was determined that the gs-A and E-A relationships were statistically significant at the p<0.01 level for both years. On the other hand, in 2019 and 2020, Ci-A relationships were significant at p<0.05 and p< 0.01 probability levels, respectively. Information on the responses of leaf gas exchange parameters to weather changes occurring during the day in kenaf plant in sub-humid climate conditions