The Effect of Combined Use of Vermicompost and Poultry Manure on the Growth and Yield of Cucumber Plants in Different Conditions of Deficit Irrigation

In sustainable farming systems, the use of organic fertilizers is of particular importance in increasing crop production and maintaining sustainable soil fertility. Nowadays, the consumption of organic foods is introduced to consumers as an alternative. The result of the application of chemical products is the crisis of environmental pollution, soil and water resources, and the health risk to human society. Nowadays, in order to reduce the effects of misuse of chemical inputs, chemical fertilizers can be replaced with organic biological fertilizers, including animal manure, compost, and green manure. In this regard, chicken manure has a positive effect on the physical, chemical, and biological characteristics of the soil, and due to its richness in uric acid, the nitrogen contained in it is used by the plant much faster than the nitrogen of other organic fertilizers. Vermicompost is considered a good source of soil fertility due to its organic materials. Organic matter in the soil improves the permeability and drainage of the soil and also prevents excessive dryness of the soil by maintaining sufficient moisture. Despite the fact that vermicompost can be used as a fertilizer in organic farming, high levels of this fertilizer may cause salinity effects in the plant, which affects the growth and development of the plant and even it can cause the death of cucumber as one of the crops sensitive to soil and water salinity. The cucumber (Cucumis sativus L.) is one of the important vegetables that can be produced in a greenhouse all year round. Fresh consumption of cucumber throughout the year has increased its production. The development of technology and the short growth period of this product has made it possible to grow it in most climate zones. Therefore, in this research, the effects of different levels of water deficit with the simultaneous application of vermicompost and chicken manure on cucumber plants in the Behbahan region have been investigated.

In this study, different levels of irrigation water, vermicompost, and poultry manure on ground cucumber were investigated. The experiment was performed in the form of split plots based on completely randomized design and the form of stacks. Treatments included three levels of poultry manure (2, 4 and 8 ton ha-1), three levels of vermicompost (3, 6 and 9 ton ha-1) and three levels of water stress (100, 75 and 50% of plant water requirement). Both vermicompost and poultry manure were applied to the soil before planting. Harvest was done every three days. Fruit weight, diameter and length, plant length, the protein of the dry matter of the fruit percentage, and leaf chlorophyll in each plot were carefully measured. Also, the yield and water productivity at the end of the season were calculated. Water productivity  Referring to the yield to irrigation water ratio, is obtained by the following relation (Payero et al., 2009):WP=Y/IR (1)In this equation, WP represents water productivity (kg/m3), Y denotes the yield (kg/ha), and IR shows the amount of irrigation water (m3/ha). Statistical analysis The analysis of variance for the results obtained from different treatments was conducted using SAS software (SAS 9.1, SAS Institute, Cary, NC, USA). The mean values of the main factors and interactive effects were compared using the Duncan method at the 1% and 5% levels of significance.

The results showed that irrigation, poultry manure and vermicompost had a significant effect on the measured parameters at the level of one and five percent probability. Reduction of water consumption reduced yield and yield components, but in this regard, no significant difference was observed between 100% and 75% of water requirement. The highest yield was obtained in the treatment of 100% of plant water requirement and consumption of 4 ton ha-1 of poultry manure and 6 ton ha-1 of vermicompost, in this regard, no significant difference was observed with the treatment of 75% of water requirement. According to the results obtained from this study, it can be said that there is no significant difference in terms of yield between treatments of 75 and 100% of plant water requirement. Therefore, the amount of water given to the plant can be reduced to 75% of the plant water requirement, and with proper management, less water can be consumed without a significant reduction in crop yield. Examining the effects of irrigation water on the amount of the protein of the dry matter of the fruit showed that the highest amount of the protein of the dry matter of the fruit (56.31%) was obtained in the treatment of 75% of the water requirement and the protein of the dry matter of the fruit was less in other treatments. The interaction effect of vermicompost and poultry manure resulted in the highest percentage of cucumber protein at a treatment of 4 tons ha-1 of poultry manure and 6 tons ha-1 of vermicompost (58.42%). However, when the simultaneous use of 8 tons ha-1 of poultry manure and different levels of vermicompost was employed, the percentage of protein in the fruit's dry matter decreased. The combination of drought stress, poultry manure, and vermicompost, along with their interaction effects, significantly influenced the chlorophyll a and b values at both the 1% and 5% probability levels. As the depth of irrigation water decreased, the amounts of chlorophyll a and b also decreased. The treatment with 100% water requirement of the plant showed the highest amounts of chlorophyll a (0.63 mg/g fresh weight) and chlorophyll b (0.36 mg/g fresh weight). However, no significant difference was observed compared to the 75% treatment. Regarding the interactions between vermicompost and poultry manure, it was found that when using 6 tons ha-1 of vermicompost to reduce yield and its components, the use of poultry manure should be reduced to 4 tons ha-1. On the other hand, when higher levels of vermicompost (9 tons ha-1) are used, the application of poultry manure should be reduced to 2 tons ha-1.

According to the results obtained from this research, it can be said that there is no significant difference in performance between the treatments of providing 75% and 100% of the water requirement of the plant, therefore, the amount of water given to the plant can be reduced to the amount of 75% of the water requirement of the plant. With proper management, less water can be consumed without significantly reducing the yield of the product.