Modeling the impact of climate warming on tomato phenology

Abstract

Climate warming is a worldwide phenomenon that impacts all sectors of life from local to global levels. Agriculture has also been severely impacted by climate warming in terms of crop phenology, productivity, and produce quality. So far research on the impact of climate warming on tomato phenology has been not published either from Pakistan or elsewhere in the world. The first objective of this study was to assess the effect of thermal trends on the temporal and spatial variation on tomato phenology from 1980 through 2023. The second objective was to apply a dynamic crop growth model, CSM-CROGRPO-Tomato, for determining the influence of climate warming, variety selection, and management practices on tomato phenology. The overall goal was to devise adaptation strategies for tomato to mitigate the potential impact of climate warming in Punjab, Pakistan. The study was conducted at 18 locations in farmers’ fields in Punjab, Pakistan, from 1980 to 2023 by using observed phenological data. The results showed that at all study sites the phenological stages were delayed. There was an average delay of 7.5 days per decade for planting, 7.2 days per decade for emergence, 4.7 days per decade for anthesis, and 3.1 days per decade for maturity. The duration of phenological phases was on average reduced by 3.3 days per decade for planting-anthesis, 2.1 days per decade for anthesis-maturity, and 5.4 days per decade for planting-maturity. Local weather station observations showed that the average air temperature increased by 2.0 °C from 1980-2023. Phenology had a statistically significant but negative correlation with the increase in temperature. Using standard cultivars across sites and years, simulated phenology was advanced due to the increase in temperature as compared to observed phenology. These findings revealed that during the last four and half decades, adaptation approaches, such as a delay in planting and growing newer varieties that require more thermal time or growing degree days, have been adopted by tomato farmers to mitigate the impact of climate warming on tomato phenology.