Water Stress Alleviation in Triticale Using of Bio-fertilizer and Intercropping Systems in an Arid Area of Southern Iran

South of Iran has been located in the dry belt and desert strip thus water stress has always been one of the serious problems in its agriculture (Buzarjomehri et al., 2020). Intercropping is the cultivation of two or more plant species in a specific land and growing season, which is important in agricultural systems with limited resources and low input (Brooker et al., 2015). Due to the differences in the rooting depth, lateral expansion, and root density of cereals and legumes, they have been the best candidates for intercropping traditionally for limited soil water and nutrient availability environments (Babalola, 1980; Haynes, 1980). Application of bio-fertilizers (PGPR bacteria) that have nitrogen (N) fixation and phosphorus (P) solubilizing activity (Azospirillum brasilense and Pseudomonas fluorescence, respectively) is a promising approach for obtaining N, P, and water-restricted areas (Tien et al, 1979; Barea, 2015). Organic manures enhance soil water holding capacity and serve as excellent slow-release sources of nitrogen (N) and phosphorus (P) in the soil (Risse et al., 2006). This study aimed to investigate the effect of different fertilizer systems (chemical, integrated, and bio-organic) on triticale grain yield and its components in sole and intercropped triticale in triticale/chickpea system under late season water stress in a hot and dry area of southern Iran (Fars province - Darab).

To evaluate the yield and yield components of triticale (× Triticosecale Wittmack) in monoculture and intercropping with chickpea (Cicer arietinum L.) under late season water stress conditions, a split-factorial experiment in a randomized complete block design with three replications was implemented at the research field of the College of Agriculture and Natural Resources of Darab - Shiraz University in 2019-2020 growing season. Treatments were two levels of irrigation (Ir): [1- normal (IRN): irrigation based on the plant water requirement up to the physiological maturity stage (ZGS92) and 2- water stress (WS): irrigation based on the plant water requirement up to the milking stage] as the main plots and three fertilizer sources (FS) [1- chemical: ( 50 kg P ha-1 + 150 kg N ha-1), 2- integrated: (25 kg P ha-1 + 75 kg N ha-1 + 20 tons sheep manure ha-1 + inoculation with Pseudomonas fluorescens and Azospirillum brasilense) 3- bio-organic: 40 tons sheep manure ha-1 + inoculation with Pseudomonas fluorescens and Azospirillum brasilense] and two cropping systems (Cs) [1- monoculture of triticale, 2- intercropped triticale with chickpea (1:1)] as the sub-plots. Triticale grain yield and its components were measured and the harvest index (%) was calculated. Data were analyzed using SAS 9.1 software and the means were separated by the least significant difference (LSD) test at 5% probability level.

The results demonstrated that water stress reduced the grain yield and its components in triticale, with the extent of reduction varying among different treatments. In the Ir × Cs interaction, the Ws treatment reduced the triticale grain yield as compared to IRN by 38% and 55 % in the intercropped and sole-triticale, respectively. The Ir × Fs interaction showed that the grain yield decreased by water stress as a function of the fertilizer system (60.4%, 43.7%, and 30.7% reduction in the chemical, integrated, and bio-organic treatments, respectively). Evaluation of the results related to the triticale yield components (grain weight, biological yield, and harvest index) also showed that the Ws treatment reduced these traits. However, the least reduction occurred in bio-organic fertilizer as compared with the other fertilizer systems (significant Ir × Fs interaction). Furthermore, the Ir × Cs interaction showed that the Ws treatment reduced triticale grain weight and its biological yield as compared to IRN in both cropping systems with different manners. The least reduction of their traits by Ws treatment was showed in intercropped triticale as compared to its sole cropping.

Based on the results of this study, intercropped triticale with chickpea and using of bio-organic fertilizer were recommended for hot and dry areas of southern Iran where water stress may occur at the end of the growing seasons. Using these strategies leads to water stress alleviation and therefore less reduction of triticale grain yield in these environments.