‘ImageJ’ Based Screening Method for Field Pea Germplasm against Pea Leaf Miner (Phytomyza horticola Goureau)

Accurately estimating crop infestation caused by insect pests is crucial, especially when screening a large panel of genotypes for potential resistant sources. The infestation by the pea leaf miner (PLM) is characterized by distinctive linear mines, often assessed by counting the number of infested leaves or visually approximating the infested leaf area. However, conventional estimation methods frequently suffer from inaccuracies. To counter this limitation, digital images of infested leaves were processed using ‘ImageJ’ software to precisely map both the total and infested leaf areas. This methodology was employed to evaluate the susceptibility of twenty different field pea (Pisum sativum L.) genotypes to PLM. The analysis revealed that foliage damage was highest in DPFPD 62 (10.2%) and lowest in Pant P 72 (0.55%). Additionally, three out of the twenty genotypes were categorized as ‘highly resistant’. Results indicated a negative correlation of foliage damage by PLM with leaf thickness (p = 0.008) and SPAD chlorophyll meter readings (p = 0.068). While a significant positive correlation was observed between foliage damage and leaf size/area (p = 0.002). Consequently, the precise estimation of PLM infestation through image analysis could offer a promising approach to gain in-depth insights into characterizing infestation severity in relation to host plant traits.