Document Type : Original Article

Authors

1 Ph.D. Student, Department of Agronomy and Plant Breeding, Karaj Branch, Islamic Azad University, Karaj, Iran

2 Assistant Professor, Department of Agronomy and Plant Breeding, Karaj Branch, Islamic Azad University, Karaj, Iran

3 Professor, Department of Agronomy and Plant Breeding, Karaj Branch, Islamic Azad University, Karaj, Iran

4 Assistant Professor, Seed and Plant Improvement Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran

Abstract

Introduction
According to studies, the agricultural sector is the largest consumer of water and in this sector, paying attention to optimal water consumption is very important. On the other hand, climate change and the spread of environmental stresses in recent years have reduced crop yields; therefore, the need to identify appropriate solutions to deal with such situations is fully felt. Restoring diversity to agricultural ecosystems and its effective management is recognized as one of the important strategies in sustainable agriculture. Mixed cropping as a sample of sustainable systems in agriculture pursues goals such as creating ecological balance, greater utilization of resources, and increasing crop yields. The most important benefit of intercropping systems compared to monoculture systems is the increase in production per unit of area, which of course has not always been achievable and this advantage is achieved only when the plants that make up the mixture are completely different in terms of how and how much to use growth factors (water, light, and nutrients). Therefore, when plants with different morphological characteristics are grown in a mixture next to each other, they can make optimal use of environmental factors and as a result, their total yield increases per unit of area. The present study aimed to evaluate the forage production potential in the replacement and additive intercropping systems of sorghum and red clover under different irrigation regimes.
Materials and methods
This experiment was conducted as split plots based on a randomized complete block design with three repetitions during the 2017 and 2018 cropping seasons at the Research Farm of Damavand Natural Resources Department. The main factor was the irrigation regime at three levels including irrigation with 100% field capacity (full irrigation as control), irrigation with 75% field capacity (moderate stress), and irrigation with 50% field capacity (severe stress). Different cropping systems were considered as sub-factors, including 75% sorghum + 25% clover, 50% sorghum + 50% clover, and 25% sorghum + 75% clover as replacement intercropping systems; 100% sorghum + 50% clover, 50% sorghum + 100% clover, and 100% sorghum + 100% clover as additive intercropping systems, and the monocultures of sorghum and red clover as control. Each experimental plot consisted of six planting rows with a length of six meters with a distance between the lines of 60 cm. In order to prevent water leakage to adjacent plots, the distance between the main plots was four planting lines. In this experiment, forage sorghum of the Speedfeed cultivar and red clover of the Nassim cultivar were used. For planting sorghum and clover in monoculture treatments, 15 and 25 kg of seeds per hectare were used respectively. Also, for planting intercropping treatments based on mixing ratios of 25, 50, and 75%, 3.75, 7.50, and 11.25 kg of sorghum seeds and 6.25, 12.50, and 18.75 kg of clover seeds per hectare were consumed respectively. Experimental treatments were irrigated by the furrow method. The irrigation cycle was adjusted based on draining 40% of available water in the root zone under full irrigation conditions. Irrigation water depth in full irrigation treatment was determined based on the soil moisture deficiency (relative to the point of field capacity) at the time of irrigation through sampling. Irrigation water depths in moderate and severe stress treatments were considered based on 75% and 50% of full irrigation water depth, respectively. It should be noted that after the establishment of sorghum plants, thinning operations were performed and its density was adjusted based on 20 plants per square meter. In this experiment, the planting pattern was in rows and the change of mixing ratios was applied based on the change in the number of planting rows of sorghum and clover. In monocultures and replacement intercropping systems, planting operations were performed in the middle of the ridges, while in additive intercropping treatments, a two-row pattern was used and each species was planted on one side of the ridges.
Results and discussion
The results of variance analysis showed that the effect of year, irrigation regime, and cropping system and the interaction of irrigation regime × cropping system on fresh and dry forage yield of clover, sorghum, and total yield were significant. The highest fresh and dry forage yields (65.169 and 14.059 ton ha-1, respectively) were obtained in the additive intercropping system of 100% sorghum + 100% clover under the full irrigation regime, whereas the minimum fresh and dry forage yields (4.191 and 0.920 ton ha-1, respectively) were recorded in clover monoculture under severe drought stress. Under moderate and severe drought stress, the maximum fresh and dry forage yields were obtained in sorghum monoculture and then in the additive intercropping system of 100% sorghum + 100% clover. Furthermore, the effect of the cropping system and the interaction of irrigation regime × cropping system on the land equivalent ratio (LER) for fresh and dry forage production were significant. The highest land equivalent ratio for fresh and dry forage production (1.719 and 1.723, respectively) was obtained in the additive intercropping system of 100% sorghum + 100% clover under full irrigation, whereas the lowest land equivalent ratio for fresh and dry forage production (1.024 and 1.022, respectively) was recorded in replacement intercropping system of 25% clover + 75% sorghum under full irrigation.
Conclusion
According to the results of this study, the additive intercropping system of 100% sorghum + 100% clover can be recommended as the superior treatment in all irrigation regimes, whereas sorghum monoculture was suitable only in moderate and severe drought stress regimes.

Keywords

Main Subjects

Abdi, M., Habibi, M., 2018. The effect of water deficit stress on forage quality and quantity of two forage sorghum cutivars. Journal of Crop Ecology. 13, 35-40. [In Persian with English summary].
Ahlawat, A., Ahrama, R., 2004. Water and nitrogen manegment in wheat-lentil intercropping system under late-season condition. Journal of Aricultural Science. 105, 697-701.
Alderfasi, A.A., Selim, M.M., Alhammad, B.A., 2016. Evaluation of plant densities and various irrigation regimes of sorghum (Sorghum bicolor L.) under low water supply. Journal of Water Resource and Protection. 8, 1-11.
Alizadeh, B., Mostafavi, K. and Zamanian, M., 2017. Study of drought tolerance of Berseem and Persian clover cultivars. Iranian Journal of Agronomy and Plant Breeding. 12, 67-76. [In Persian with English summary].
Ashoori, N., Abdi, M., Golzardi, F., Ajalli, J., Ilkaee. M.N., 2021. Forage potential of sorghum-clover intercropping systems in semi-arid conditions. Bragantia, 80, e1421.
Baghdadi, A., Paknejad, F., Golzardi, F., Hashemi, M. and Ilkaee, M.N., 2021. Suitability and benefits from intercropped sorghum–amaranth under partial root‐zone irrigation. Journal of the Science of Food and Agriculture. 101(14), 5918-5926.
 Bakhtiyari, F., Zamanian, M., Golzardi, F., 2020. Effect of mixed intercropping of clover on forage yield and quality. South-Western Journal of Horticulture, Biology and Environment. 11, 49-65.
Balazadeh, M., Zamanian, M., Golzardi, F., Mohammadi Torkashvand, A., 2021. Effects of limited irrigation on forage yield, nutritive value and water use efficiency of Persian clover (Trifolium resupinatum) compared to Berseem clover (Trifolium alexandrinum). Communications in Soil Science and Plant Analysis. 52(16), 1927-1942.
Dashtaki, M., Chaichi, M.R., 2012. Intercropping of sorghum and chickling pea in limited irrigation regimes. Iranian Journal of Field Crop Science. 43, 311-321. [In Persian with English summary].
Fang, G., Martin, K., Guoyu, W., Peter, E.L., Wopke, W., 2016. Yield and yield components of wheat and maize in wheat-maize intercropping in the Netherlands. European Journal of Agronomy. 76, 17-27.
Francis, C.A., 1989. Biological efficiencies in multiple-cropping systems. Advances in Agronomy. 42, 1-42.
Golzardi, F., Baghdadi, A., Keshavarz Afshar, R., 2017. Alternate furrow irrigation affects yield and water-use efficiency of maize under deficit irrigation. Crop and Pasture Science. 68(8), 726-734.
Golzardi, F., Vazan, S., Moosavinia, H., Tohidloo, G., 2012. Effects of salt and drought stresses on germination and seedling growth of swallow wort (Cynanchum acutum L.). Research Journal of Applied Sciences, Engineering and Technology. 4, 4524-4529.
Khajeh Khezri, A., Rezaei Estakhroeih, A., Golestani Kermani, S., 2018. Evaluating the effects of alternative and regulated deficit irrigation on yield and some components in intercropping (Sorghum – Red bean). Irrigation Sciences and Engineering. 41(2), 77-92. [In Persian with English summary].
Khazaei, A., 2017. Evaluation of drought tolerance in forage sorghum (Sorghum bicolor L. Moench) promising lines. Iranian Journal of Crop Sciences. 19(1), 73-85. [In Persian with English summary].
Khoramivafa, M., Ghasemi, E., Farhadi, B., Najaphy, A., 2013. The water use efficiency in forage maize at maize/faba bean realy intercroping in deficit irrigation and no tillage systems. International Journal of Agronomy Plant Production. 4, 3134-3139.
Lithourgidis, A.S., Vasilakoglou, I.B., Dordas, C.A. Yiakoulaki, M.D., 2006. Forage yield and quality of common vetch mixtures with oat and triticale in two seeding ratios. Field Crops Research. 99, 106-113.
Nazari Sh., Zand, E., Asadi, S., Golzardi, F., 2012. Effect of additive and replacement intercropping series of corn (Zea mays L.) and mungbean (Vigna radiate L.) on yield, yield components and weed biomass. Weed Research Journal. 4(2), 97-109. [In Persian with English summary].
Raei, Y., Javanshir, A., Ghasemi Golezani, K., 2006. Evaluation of sorghum (Sorghum bicolor) and egyptian clover (Trifolium alexandrinum) intercropping system. Agroecology Journal. 2(5), 19-32. [In Persian with English summary].
Rezvan Bidokhti, S., 2004. Comparison of different combinations of planting corn and beans. Master of Science Thesis in Agronomy. Faculty of Agriculture. Ferdowsi University of Mashhad, Iran. [In Persian with English summary].
Sani, B.M., Danmowa, N.M., Sani, Y.A., Jaliya, M.M., 2011. Growth, yield and water use efficiency of maize-sorghum intercrop at Samaru, Northern Guinea Savannah, Nigeria. Nigerian Journal of Basic and Applied Sciences. 19, 253-259.
Sanjani, S., Hosseini, M.B., Chaichi, M.R., Rezvan Beidokhti, S., 2009. Effect of additive intercropping sorghum: cowpea on weed biomass and density in limited irrigation system. Iranian Journal of Field Crops Research. 7(1), 85-95. [In Persian with English summary].
Sherif, M.A., Mahmoud, M.A., 2015. Effect of deficit irrigation and soybean/maize intercropping on yield and water use efficiency. International Jouurnal of Current Microbiology and Applied Sciences. 4, 777-794.
Woldeamlak, A., Kropff, M.J., Struik, P.C., 2006. Effect of drought stress on barley-wheat intercropping. African Crop Science Jouenal. 14, 185-195.
Yamori, W., Hikosaka, K., Way, D.A., 2014. Temperature response of photosynthesis in C3, C4, and CAM plants: temperature acclimation and temperature adaptation. Photosynthesis Research. 119, 101-117.
Yilmaz, S., Özel, A., Atak, M., Erayman, M., 2015. Effects of seeding rates on competition indices of barley and vetch intercropping systems in the Eastern Mediterranean. Turkish Journal of Agriculture and Forestry. 39, 135-143.
Yu, Y., Stomph, T.J., Makowski, D., Werf, W.V.D., 2015. Temporal niche differentiation increases the land equivalent ratio of annual intercrops: A meta-analysis. Field Crops Research. 184, 133–144.