Shade net and mulching measures for improving soil and plant water status of fig trees under rainfed conditions

Abstract

Prolonged drought conditions and soil desiccation have caused extensive damage and reduction in yields of the largest rain-fed fig trees (Ficus carica L. ‘Sabz’) grove located in the semi-arid region of Estahban, Iran. In this experiment, the effect of suspended shade net and two types of water penetration systems covered with organic mulch on plant water status and productivity of the rain-fed fig trees on the foothill slopes with traditional micro-catchment were investigated during 2018–2020. The first experimental factors included -(Ctrl.) without shade net and -(S) covering the tree canopy with 25% shade intensity white suspended shade net; and the second experimental factors included -(Ctrl.) the local traditional practice (25 m2 bare soil micro-catchment only), -(M) application of wheat straw as organic mulch under the tree canopy with two concentrating infiltration pipes and -(MP) application of wheat straw mulch over the soil under the tree canopy with two concentrating infiltration pipes and on the surface of 4 m of overall plowing rows perpendicular to the slope to a depth of 40 cm and a width of 3 m at a distance of 2.5 m upslope of the tree trunk. MP treatment significantly increased and retained the average of soil moisture content by 79.9% in comparison with the local traditional practice. The results showed that S+MP had the greatest effect on inducing the physiological attribute of fig trees such as leaf stomatal conductance (121.1%), leaf transpiration (52.5%), leaf light-saturated net CO2 assimilation (96.6%) and the leaf water potential (30.9%) as the main effective variable in association with increment of commercial fruit yield. This treatment had the highest impacts on the increment of yield (187.7%) and commercial and healthy quality of ‘Sabz' fig dry fruit under severe drought conditions in rain-fed orchards.