JWSS - Journal of Water and Soil Science

---

Two field experiments were conducted in 1996 at the experimental station, College of Agriculture, Shiraz University at Badjgah. Fourteen cultivars consisting of eight hybrids and six open pollinated cultivars were grown in two randomized complete block designs with four replications.

 The well-watered experiment received water when evaporation reached 65±5 mm from class A evaporation pan.

The water-limited experiment was irrigated in terms of 125±5mm evaporation from class A evaporation pan. Days to flowering, days to physiological maturity, head diameter, stem diameter, number of leaves per plant, plant height, number of filled seeds per head, 1000 seed weight, kernel percentage, unfilled seed percentage, seed yield, oil percentage, oil yield and harvest index were measured.

Most of the traits including seed yield and oil yield showed considerable genotypic and phenotypic variations. Highly significant differences were observed among cultivars. In normal and water stress conditions, the highest seed yield were obtained by Louc and Armavirsky cultivars, respectively. Water stress significantly decreased yield and its components. Furthermore, days to physiological maturity reduced in response to water deficit. However, oil percentage did not differ significantly. Drought resistance indexes were calculated in order to evaluate the response of each cultivar to water deficit. No association was found between yield potential and the stress susceptibility index, suggesting that drought resistance and high yield potential may be combined to improve sunflower cultivars. In addition, it was revealed that selection for height mean productivity and stress tolerance index will improve yield and drought tolerance simultaneously. Among cultivars that were used in this study, Armavirsky, besides having a relatively higher yield, was also drought tolerant.

---

To investigate drought tolerant isolates of rhizobial symbioant of lentil (Lens culinaris L.), 12 soil samples were collected from cultivated and non-cultivated area of Golestan, Chaharmahal-O-Bakhtiari and Isfahan provinces. Local cultivars of lentil including Binam Dorosht, Ghazvini and Faridani were planted in each soil sample. After 10 weeks, a total of 324 rhizobial isolates were recovered from root nodules of the lentil plants. Evaluation of the ability of the isolates to grow at different concentration of salt showed that all isolates grew normally on 200 mM NaCl and only 20% was determined as salt tolerant isolats(>400mM). Among the isolates RL249 was classified as superior salt tolerant strain due to growing on 600 mM salt. The drought tolerance of the isolates was also examined, using PEG6000. In general, the salt tolerant isolates were also drought tolerant, however their tolerance to salinity and drought is not related to their geographical origin. In a randomized split factorial design with three replications, the effectiveness of tolerant isolates(RL249 and RL211) and a sensitive strain (RL 77) was compared on two cultivars of lentil (Binam Dorosht and Faridani) under water stress treatments with the consumptions of 50, 75,90 and 98% of soil available water. Although nodulation rate was reduced in both cultivars as the consequence of drought stresses, plants of Binam Dorosht cultivar showed high nodulation rate due to the increased fresh weight of the roots. Despite the fact that RL249 was identified as a superior nodulating and salt/drought isolate, however nodulation efficiency was decreased significantly under water stress treatments with more than 50 % of soil available water.