Pak. J. Bot., 44: 257-262, Special Issue May 2012. KOCHIA SCOPARIA AS A MODEL PLANT TO EXPLORE THE IMPACT OF WATER DEFICIT ON HALOPHYTIC COMMUNITIES MOHAMMAD KAFI *1 AND MASOUME SALEHI 2 1 Department of Agronomy, Faculty of Agriculture, Ferdowsi University of Mashhad, Iran. P.O. Box 91775-1163 2 Agricultural and Natural Resources Research Center of Golestan province, Iran. *Correspondence author: m.kafi@um.ac.ir; Tel: 00989153066269 Abstract Most halophyte species experience drought, salinity and high temperature stresses in their growth period, and sensitivity to any of these may affect plant tolerance to others. Among halophytes, Kochia scoparia have recently considered as forage and fodder crop in marginal lands. In order to evaluate interaction of saline water application and water deficit effect on growth parameters, water-salinity production function and physiological parameters, a series of experiments were conducted with different levels of saline water (1.5 to 42 dS/m) and different levels of applied water (25 to 125% of the water requirement) in the farm and greenhouse. Results showed that Kochia like other halophytes is sensitive to drought and salinity at the earliest stages of growth. Salinity reduced linear phase of growth and decreased biomass production but salinity tolerance of Kochia was improved by increasing water application. Evaluation of yield response factor under water deficit and salinity showed that there is not any significant difference among water deficit treatments up to 21 dSm -1 . There was no significant difference in biomass of medium drought stress and control. Plants showed more tolerance against drought stress, when stress was induced in the whole growth season. In all experiments, ecotypes from the arid regions, revealed a better response to drought and salinity. Under severe drought and salinity, Kochia still could produce up to 16 and 8 t DM ha -1 biomass in 2009 and 2008, respectively. Salinity tolerance of Kochia was improved by increasing water application. Results of water depletion from different soil layers showed that Kochia uptakes more water from the 30-60 cm soil depth. The soil salinity (EC e ) of this section was lower in comparison to the 0-30 cm soil depth. Additionally, the water uptake of the 30-60 cm soil depth improved the salt tolerance level of Kochia. At 75% application of water requirement, Kochia produced 90% of biomass in comparison to 100% water application. Therefore, deficit irrigation is a useful management technique for Kochia even under saline conditions. The results of the present study demonstrated that some indices regarding growth of Kochia and probably other halophytes under salinity, drought and their combination should seriously be revised. Kochia also could be considered as a forage crop or biofuel material by using saline water in semi-arid areas. Introduction Drought and salinity are the most important environmental factors inhibiting photosynthesis and decreasing growth and productivity of plants in many parts of the world. They are the major causes of crop loss worldwide, reducing average yields for most major crop plants by more than 50% (Ashraf, 2004, Qadir, 2008; Naz et al., 2010). Almost all area of Iran affected by aridity and crop production without irrigation is not possible and about 34 million ha, including 4·1 million ha of the irrigated land, are salt-affected in Iran as the consequence of naturally occurring phenomena and anthropogenic activities. The annual economic losses due to salinisation in the country exceed US$ 1 billion (Qadir et al., 2008). Conventional water resources and crops do not meet all the requirements of human societies living in dry and saline areas. Using seawater or brackish water and salt tolerant crops may be options to be considered, since there could be a greater focus on developing halophytes as cash crops in the future (Breckle, 2009). Kochia (Kochia scoparia L. Schrad) is a rapidly emerging and growing plant with potentially high yield that is widely adapted to many parts of Iran (Kafi et al., 2010). The drought and salt tolerance of Kochia indicate that it could be an important forage crop in arid and semiarid areas. It may provide a good source of forage by using saline water for irrigation in dry regions (Al-Ahmadi and Kafi, 2007). The nutritive value of Kochia, harvested at or before full bloom, and alfalfa (Medicago sativa), harvested at 20% bloom is quite similar (Knipfel et al., 1989). Coxworth & Salmon (1972) reported that Kochia seed might be a useful source of protein (29%), oil (10%) and energy for a variety of domestic animals. Jami Al- ahmadi & Kafi (2007) showed that salinity up to 10 dS m - 1 did not have considerable effect on seed germination. Extreme reduction of germination occurred at 20 dS m -1 , but more than 35% of seeds still germinated. Several studies indicate that tolerance to saline irrigation water do change as the crop develops and matures (Maas et al., 1986; Maas & Poss, 1989; Ahmad et al., 2010). A better knowledge on how salt tolerance changes during some stages of growth may improve new strategies for the utilization of saline drainage water. Domestication of salt tolerant plants which grow naturally in saline land could be introduced as new crops cultivated under environmental stresses induced by salinity and aridity. Several researchers showed that Kochia scoparia produces high biomass in saline-sodic soils or saline-sodic irrigation water (Green et al., 1986; Qadir & Oster, 2004; Steppuhn et al., 2005; Ahmad et al., 2011). In addition to its halotolerant, because of its deep rooting systems, Kochia is exceptionally drought tolerant (Madrid et al., 1996). Despite the negative impacts, irrigation is critical to sustaining and increasing agricultural production. While about 17% of agricultural land worldwide is irrigated, this 17% accounts for about 40% of the total global food harvest (FAO, 2002). Moreover, per capita arable land has decreased over the years, from a worldwide average of 0.38 ha in 1970 to 0.28 ha in 1990, and some analysts project a further decrease to 0.15 ha in 2050 (Ghassemi et al., 1995). Hence, increased production must come from increased average yields, increases that will be possible