Evaluation of cultivation environment and management based on LAI measurement in farmers’ paddy fields in Pursat province, Cambodia

Rice is by far the most important crop in Cambodia. The improvement of its productivity is strongly recommended, but information about cultivation environment, management and their effects on rice production in farmers’ paddy fields is quite limited. This study periodically measured the leaf area index (LAI) by using a plant canopy analyzer and conducted yield, water, soil and management investigations in 77 farmers’ paddy fields in the Bakan district, Pursat province, Cambodia in 2014. Because the LAI showed linear growth in almost all farmers’ fields, the LAI growth rate was determined by linear regression. The grain yield ranged from 70.8 g m⁻² to 499.0 g m⁻² and was positively correlated with the maximum LAI. The variability in the maximum LAI was mainly explained by the LAI growth rate, while the growth period had a significant correlation with the maximum LAI only in the broadcast fields, where earlier planting led to larger LAI. The result of the ANCOVA shows that the LAI growth rate was affected by seeding date, water status and soil condition (C content and C/N ratio) while the effect of planting method (transplanting/broadcasting) and N fertilizer was non-significant. The non-significance of effect of N fertilizer may imply the timing or method of application is improper. The results suggest that the key means to improve rice productivity are effective application of fertilizer and selection of planting methods dependent on the soil fertility, together with water-saving irrigation method.