Integrated Analysis of Agronomic Traits and Fruit Damage on Three Cucurbit Crops in the Ruzizi Plain, Eastern DR Congo: Climatic Influence, Soil Characteristics, Crop Development and Yield Dynamics

Background An experiment was conducted from January to April 2024 in the eastern Democratic Republic of Congo (DRC) to assess the influence of plot-specific environmental factors on the performance of three cucurbit crops: watermelon ( Citrullus lanatus , variety Sukari F1), squash ( Cucurbita pepo , variety Hybrid F1 Kalabasa Suprema), and cucumber ( Cucumis sativus , variety Ashley). The study aimed to evaluate the effects of soil fertility, climatic variables, and pest pressure on growth and yield outcomes. Methods A randomized block design with three replications was implemented across three plots. Soil samples were analyzed at the Soil Sciences Laboratory of the Catholic University of Bukavu for pH, organic carbon, nitrogen, phosphorus, potassium, and cation exchange capacity. Climatic data, including maximum temperature, dew point, relative humidity, and precipitation, were obtained from the NASA/POWER (CERES/MERRA2) database due to the lack of a local weather station. Crop development, fruit yield, and incidence of fruit fly damage were recorded throughout the cultivation cycle. Data were analyzed using R (version 4.2) and R Instat software, applying Kruskal-Wallis tests, Dunn’s post hoc analysis, Spearman correlations, and principal component analysis (PCA). Results Climatic trends indicated a transition from the rainy to the dry season, marked by rising temperatures and declining relative humidity. Soil fertility varied across plots, with squash plots showing the highest nutrient levels. Although flowering and crop duration did not differ significantly among species, watermelon tended to mature earlier. Significant differences in cucumber fruit weight and pest incidence in watermelon and squash were observed across plots, particularly in Plot C, which consistently exhibited higher fruit fly pressure. PCA and correlation analyses confirmed the strong association between pest-damaged fruits and higher incidence rates, as well as an inverse relationship with healthy fruit production. Conclusion Plot-specific environmental conditions significantly influenced cucurbit performance and fruit fly infestation. These findings highlight the importance of localized soil fertility management and targeted pest control strategies to enhance productivity and minimize yield losses in tropical smallholder systems.