Weather Influences on the Gas Exchanges of Neem Trees

The neem tree is a prospective agroforestry tree with significant demand in the medical and timber industries. It has a specific season of reproductive phase in a year, mostly from February to July in India. A study was organized to identify the influence of various weather parameters on the reproductive phase at Tamil Nadu Agricultural University, Coimbatore during 2023 and this paper is confined to weather on gas exchange parameters. The results inferred that the reproductive statuses of neem trees, including regular flowering, dormant flowering, and alternate flowering trees, exhibited notable differences in gas exchange parameters such as photosynthetic rate, Stomatal conductivity, and transpiration rate due to observed variability in prevailing weather conditions. Alternate-bearing trees were found to have higher gas exchange parameters when compared to regular flowering and nonflowering trees. The neem trees recorded significantly higher values of these parameters during the preflowering compared to the flowering stage. During both the preflowering and flowering stages, the rainfall, relative humidity, minimum temperature, and wind speed, exhibited a statistically non-significant negative influence on gas exchange activities. The maximum temperature exhibited a positive impact during the pre-flowering stage and a negative impact throughout the flowering phase whereas diurnal temperature exhibited a positive effect on the gas exchange parameter during both the preflowering and flowering stages of the neem tree.