Effects of Organic Mulches on Soil Properties and Growth Attributes of Caper (Capparis spinosa L.) for Cultivation in the Coastal Rangelands of Southern Iran

Caper is a drought tolerant plant and natural feed of animal in the coastal rangelands of Iran. However, due to soil salinity and alkalinity issues, the growth of such native plants in the southern soils of Iran is limited. This study was conducted to evaluate the effect of various mulches including oil mulch, cement, sugarcane bagasse, palm waste and their combination, on soil properties and plant growth characteristics of caper plant in 2019 in Deylam, Iran. The results showed that using sugarcane bagasse and palm waste mulch significantly increased the soil nutrients (available nitrogen, phosphorus and potassium). Similarly, both mulches significantly increased soil moisture with values of 24.61 and 23.03% and decreased electrical conductivity (EC) with values of 83.60 and 81.46 dS/m, and pH (6.77 and 6.95), respectively (p <0.01). In contrast, application of non-organic mulches such as oil and cement mulch and their combination let to decreases of soil moisture with values of 17.03%, 18.40% and 18.97%, respectively (p <0.01). Using sugarcane bagasse mulch and palm compost mulch significantly increased stem length (20.26 and 22.43 cm), weight of the aerial part of plant and SPAD value (41.40 and 41.97 unit) of caper plant, respectively (p <0.01). There was negative correlation between plant weight and soil EC (R=-0.74) and pH (R=-0.57). Findings suggested the significant effect of organic mulches on adjusting soil EC and pH for improving the establishment of caper plants in the coastal rangelands of Iran.