Kochia -Kochia scoparia L. Schrad- is a tolerant plant to both saline and water deficit conditions and have recently considered as forage feed for livestock in saline and arid regions. Understanding the belowground physiological responses and biomass allocation of Kochia\\\\\\\\\\\\\\\'s under water deficit conditions may help to realize more potentials of this plant. To achieve such knowledge of root and shoot, a pot experiment was carried out in a completely randomized design with three replications. Nine water deficit stress treatments imposed to plants at the vegetative and reproductive stages: control; NS-NS -no stress= 100% field capacity -FC-- during total growth period, moderate stress -MS=70% FC- during total growth period -MS-MS-, severe stress -SS=30% FC- during total growth period -SS-SS-, MS-NS, SS-NS, NS-MS, NS-SS, MS-SS, SS-MS. The results indicated that water deficit stress decreased relative water content, membrane stability, fresh and dry weight and increased malondialdehyde, superoxide dismutase, catalase, free amino acids, proline and soluble sugars in root and shoot of Kochia. Our results indicate that under water deficit stress, the amount of osmolytes and enzymatic antioxidants increased in root and shoot of Kochia to maintain osmotic balance and membrane stability. It is also found that water deficit stress severely decreased biomass of both roots and shoots, but allocation of photosynthates to shoots or roots was similar across all irrigation regimes. Such performance may explain Kochia scoparia tolerance to saline and water deficit conditions.

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