Evaluation of Interactions of Quantitative Traits on Performance of Cucumber Cultivars in Intercropping with Okra

The practice of intercropping (mixed cropping) may represent a promising sustainable solution to improve crop production from small parcel of land. Intercropping, a technique of growing two or more crops simultaneously in the same field, is an agro-ecological practice for sustainable crop intensification. Intercropping ensures efficient utilization of light and other resources, reduces soil erosion, suppresses weed growth, and thereby helps to maintain greater stability in crop yields. It also guarantees greater land occupancy and thereby higher net returns. Although many researches have evaluated the effects of intercropping of common fruit vegetable crops like cucumber (Cucumis sativus), there is still paucity of information on this. From a practical point of view, information on cucumber and okra (Esculentus abelmoschus) intercropping is not available. Okra and cucumber are among the important fruit vegetables, and therefore conducting research on their intercropping is important to achieve a better understanding of interactions of the mixed cultivation of these two plants. The objectives of this research were finding the best cucumber cultivars in mixed cultivation with okra in terms of qualitative and quantitative traits, investigating the correlation between traits in mixed crops, and comparing the mixed crops in different years and selection of the most beneficial cultivation.           

In order to investigate the relationship between yield and its components and to select the best mixed crop of okra and cucumber in terms of quantitative and qualitative traits, an experiment was conducted based on randomized complete blocks design with three replications at greenhouse condition under the supervision of the Research Institute of Horticultural Sciences of Varamin, Iran, during two years (2020-2021). Ten cucumber cultivars including ‘Viola’, ‘Mirsoltan’, ‘Mito’, ‘Emilie’, ‘CUB-9042’, ‘FC-21’, ‘CUB-9045’, ‘FC-27’, ‘NAGIN’, ‘NEGIN’ mixed with okra cultivar ‘Baker’ were used in this study. The evaluated traits were fresh weight of fruit in each node, plant height, stem diameter, fresh yield of fruit, dry yield of fruit, number of internode, fruit diameter, fruit length, fruit number and leaf chlorophyll content.

The results of combined analysis of variance showed that there was a significant difference between intercrops in terms of evaluated traits. The interaction of year and intercropping was also significant on all traits except stem diameter. Results of mean comparison based on Duncan’s test showed that cultivation of okra with greenhouse cucumber cultivars including ‘Viola’, ‘Fc-21’ and ‘Emilie’ are suitable intercrops based on fruit weight in each node, plant height, stem diameter, fresh yield of fruit, dry yield of fruit, internode number, fruit diameter, fruit length, fruit number, chlorophyll a, chlorophyll b and total chlorophyll content. Based on results of the evaluation of intercrops using a multifaceted view during experimental years, mixed cultivation of okra and greenhouse cucumber cultivars including ‘Viola’ and ‘Emilie’ were selected as desirable intercrops. Correlation analysis results showed that there was a positive correlation between the characteristics of fresh and dry yield of fruit and chlorophyll a content, fruit number, fruit length, stem diameter, plant height and fruit diameter and internode number and chlorophyll b content. According to principal components analysis the first four components justified the main part of variation. According to the ratio of land equality (LER), cultivation of okra with cucumber cultivars including ‘Mirsoltan’, ‘Emilie’, ‘CUB-9042’, ‘CUB-9045’ were the most profitable intercrops. Based on several studies, intercropping will lead to better and more efficient use of environmental resources by plants. This technique can considerably reduce weed growth and distribution in agricultural fields. There are several reports on promising results of intercropping in different horticultural crops with improved qualitative characteristics and higher yield performance.

In conclusion, the results showed that cultivation of okra (cv. ‘Baker’) with the greenhouse cucumber cultivars including ‘Mirsoltan’, ‘Viola’ and ‘Emilie’ could be considered as desirable intercrops. Also, intercropping okra with cucumber had higher desirability than pure cultivation of okra in terms of yield and some of most important quantitative characteristics.