11-Oct-2023
Exploring the Potential Causes of Leaf Yellowing in Paddy Cultivation During the Maha Season 2022 23
In the recent Maha season (2022/23), a concerning issue of yellowing rice plants was observed in several rice-growing regions accompanied by noticeable growth retardation and yellowing symptoms.
Recognizing the need for rigorous scientific investigation, the Faculty of Agriculture, University of Peradeniya initiated an in-depth study to uncover the underlying causes of rice crop yellowing. A specialized team of scientists focused on specific paddy tracts in Kandy, Rathnapura, and Hambantota districts and extensive field observations, interviews with farmers, and soil and plant sample collection were done February-March 2023.
Measurement of soil parameters revealed substantial variability of measured soil parameters across sites. From the sites studied, 95% and 77% of sites had low conte
nts of plant available P and K, respectively. Thus, in most of the sites, soil P and K were not at optimum levels to support crop growth. Leaf N, P, and K concentrations largely fell within reported ranges, although specific samples indicated deficient P levels. Root knot nematode infections at varying incidence (6-83 %) were reported from rice and weed plants of all three locations with % occurrence ranging from 14- 75.
Despite the lack of significant differences in soil parameters between areas displaying rice yellowing and those without, a potential link between sub-optimal nutrient inputs and crop performance emerged. The results indicated that there is a high risk of spreading the nematode infection to the next crop. Consequently, implementing measures for managing the root-knot nematode infection in rice cultivation is crucial. The study highlighted the pivotal role of nutrient management practices and soil nutrient availability in influencing crop health and overall performance in the studied paddy fields. As a recommendation, the study emphasizes the necessity of prioritizing nutrient management practices, refining fertilizer application strategies, enhancing soil nutrient availability and reducing the spread of nematode infestation, to address rice yellowing issues and enhance overall crop productivity.
