Effect of Different Habitats Conditions on Citrullus colocynthis (L.) Schrad. Growing Naturally in Egypt and Kingdom of Saudi Arabia

Abstract

Harsh environmental conditions are major factors limiting plants production and development, including Citrullus colocynthis L. (C. colocynthis). The present investigation provides an analysis of soil properties and plant compounds of C. colocynthis in Wadi Hebran, Saint Katherine, South Sinai, Egypt and Wadi Al-Akhder, Tabuk Province, KSA at dry and wet seasons, and focuses on the relationship between the environmental factors and phytochemical compounds using principal component analysis (PCA). According to ANOVA, the experimental factors (locations, depths, seasons and their interactions significantly influenced the physico-chemical properties of soil and chemicals present in C. colocynthis (P < 0.05 or 0.01). Wadi Hebran at both seasons significantly promoted most mechanical and chemical properties in soil and most chemical compositions in C. colocynthis compared with Wadi Al-Akhder. While the significantly positive highest impact on photosynthetic pigments contents was found in Wadi Al-Akhder at both seasons. The dry season in the two locations significantly increased the total carotenoids, Chl.a/b, total pigment, P %, total carbohydrate, proline, catalase enzyme, peroxidase enzyme, ascorbic acid and malondiadehyde compared to the wet season. Based on PCA analysis, the first two PCs explain more than 84% of the total variance in the original variables and mainly distinguished the soil and plant variables in different groups during each location or between the two locations at both seasons. The first PC showed the highest positive correlation with some soil variables (EC, K+, and Cl-) and plant variables (P, total carbohydrate, proline, catalase enzyme, peroxidase enzyme and malondiadehyde). While the second PC exhibited a highly positively correlated with Ca2+, S- and water content in soil and with Chl.b, K+, Ca2+, N, water content, crude protein, crude fiber, total ash and superoxide enzyme in C. colocynthis plants. Positive correlations among most soil and plant variables were found, but they differed in their degree and consistency in quantity. PCA application indicated that the above soil variables are related closely to the above plant variables of C. colocynthis in the two locations. The results of PCA could be useful and used as a suitable method for studying the stresses tolerance mechanisms of plants under hard environmental conditions.