عنوان مقاله [English]
Background and objectives: In all arid and semi-arid area irrigation is necessary for crop production; salinization of soil is also unavoidable. Therefore, for sustainable crop production in such areas, growing crop species with higher threshold and lower yield reduction under saline and water shortage conditions is needed. Agriculture and animal husbandry are integrated in arid and semi-arid regions. Therefore, providing of forage for livestock in these areas is one of the main concerns of farmers. Kochia (Kochia scoparia L. syn Bassia scoparia L.) is an annual plant with high tolerance to salt and drought stress. It is capable to rapid established in saline soils, and is a ground cover plant that can introduced as an alternative fodder, in arid and semi-arid areas. Therefore, the aim of this study was to evaluate the drought tolerance of kochia in irrigation with saline water at different growth stages with emphasis on the forage characteristics.
Materials and methods: Experiment was conducted as split-plot based on randomized complete block design with three replications at the salinity research station of center of excellence for special crops of Ferdowsi University of Mashhad, Iran in 2008. In order to stimulation of drought stress at first and final growth stages drought stress was applied for four weeks. Three levels of drought stress (control, no irrigation in vegetative stage (recovery treatment) and no irrigation at reproductive stage for one month (stress treatments), and two kochia accessions (Birjand and Borujerd) were arranged as main and sub plots, respectively. Plants were irrigated with underground water with electrical conductivity (EC) of 5.2 dS m-1. Forage harvesting was carried out after the third-stress treatment, in full flowering stage.
Results: The results showed that plant height in vegetative growth stage was more sensitive to water stress than the reproductive stage in kochia. In all irrigation treatments at different growth stages, Borujerd accession had higher plants height than Birjand accession and the highest plant height reduction in both accessions occurred in drought stress during vegetative growth stage. Branch number and forage yield in kochia were not affected by Irrigation treatments. Total dry matter percent of drought stress treatment at both reproductive stages were eight and nine percent higher in control and vegetative stage, respectively. Stems and leaves yield of Borujerd and Birjand accessions were not significantly affected by irrigation treatments. The highest and the lowest leaf to stem ratio were obtained in drought stress at vegetative and reproductive growth stage, respectively.
Conclusion: Four weeks irrigation cuts at vegetative and reproductive stages did not affect forage yield of kochia, and showed the high capability to recover the adverse effects of drought stress in vegetative growth stage. Generally, kochia has morphological features for introduce as a forage crop in saline and arid areas. In addition, the physiological mechanisms of drought and salt tolerance of kochia may introduce it as a candidate forage species for cultivation and to help feed the livestock in areas where salinity and drought stress is dominant.