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In order to examine the effect of sowing date and seeding level on yield and yield components of cumin, a factorial experiment was conducted in 2009-2010 based on a randomized complete block design with three replications. The main plot was sowing date at four levels (December 9, January 8, February 7 and March 9) and the sub-plot was seeding level at three levels (15, 30 and 45 kg/ha) The results showed that sowing date significantly affected 1000-seed weight, seed and biological yields, seed and biomass yields of single plant at 1% probability level. Also, seeding level significantly affected biological yield and seed and biomass yields of single plant at 1% probability level and seed yield and harvest index at 5% probability level. The interaction between sowing date and seeding level significantly affected seed yield, 1000-seed weight, harvest index and seed and biomass yields of single plant. Means comparison showed that the delay in sowing from January 8 to March 9 decreased seed and biological yields by 59.04 and 63.01%, respectively. In addition, the delay in sowing from January 8 to February 7 and March 9 significantly decreased seed yield of single plant by 50.7 and 70.7%, respectively. According to the results, as seeding level was increased from 15 to 45 kg/ha, seed yield, decreased by 4%, but biological yield increased by 13.28%. Given the results, it can be recommended to use sowing date of January 8 with the seeding level of 15-30 kg/ha for the cultivation of cumin in Birjand, Iran.

In order to study the effect of N fertilizer rates on yield and yield components of rice cultivars, a study was carried out in Rice Research Institute of Rasht, Iran in 2008. It was a two-variable factorial experiment based on a randomized complete block design with three replications. The main plot was N fertilization at four rates of 0, 30, 60 and 90 kg/ha and the sub-plot was rice cultivar at three levels of Hashemi, Ali-Kazemi and Khazar. The results of analysis of variance showed that the change in applied N rate significantly affected seed yield, N accumulated in plant and seed and N recovery and physiological efficiencies. Also, the effect of cultivar was significant on seed yield, N accumulated in plant and seed and N agronomical and physiological efficiencies, but the interaction between N and cultivar did not significantly affect any studied traits. Means comparison showed that as N rate was increased from 0 to 90 kg/ha, seed yield and N accumulated in seed increased by 84.5 and 65%, respectively; but as it was increased from 30 to 90 kg/ha, N recovery efficiency decreased by 33.8% and N physiological efficiency increased by 40%. Cultivar Khazar with the average seed yield of 3424.51 kg/ha, N agronomical efficiency of 24.43 kg/kg, N recovery efficiency of 42.11% and N physiological efficiency of 58.97 kg/kg had the highest potential of using applied N among the studied cultivars. In total, the results indicated that cv. Khazar was better to be cultivated accompanied with the application of 90 kg N/ha in order for having the maximum production and minimum lose of applied N under the conditions of the current study.

In order to study the effect of water deficit stress and different nitrogen levels on flower yield and yield components of Calendula officinalis L., an experiment was conducted as split plot design based on randomized complete blocks with three replications, at research field of Islamic Azad University of Birjand branch in 2009.In this research water deficit stress set as main factor with three levels (irrigation after 60, 120 and 180 mm cumulative evaporation from pan class A) and nitrogen set as sub factor with four levels (0, 60,120 and 180 kg N.ha -1 ). The number of flowers per m 2 was 2.58 times greater in the treatment of irrigation after 120 mm accumulative evaporation than in the treatment of irrigation after 180 mm, but it showed an 11.2% loss compared with the treatment of irrigation after 60 mm accumulative evaporation. Also treatment of irrigation after 180 mm accumulative evaporation decrease of single flower weight by 13.3 and 18.2% at the treatments of irrigation after 120 and 60 mm accumulative evaporation, respectively. Means comparison showed that the increase in N fertilization rate from 0 to 180 kg N.ha -1 significantly increased the number of flowers per m 2 , flower fresh and dry yield by 33.7, 36.8 and 35.4% respectively. Finally, the results indicated that treatment of irrigation after 120 mm evaporation with 120 kg N. ha -1 application is suitable for marigold cultivation in Birjand.