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In a 2-year field experiment (2009-10 and 2010-11) 30 wheat cultivars were compared under with and without late season drought stress conditions. The experiments were conducted as a split plot based on randomized complete block design with four replicates at Research Farm of College of Agriculture, Shiraz University. Drought stress treatments (without stress, as control, and irrigation cutting off at anthesis stage) and wheat cultivars were assigned into main plots and sub plots, respectively. In this study MEAN PRODUCTIVITY (MP), stress susceptibility index (SSI), stress tolerance index (STI), GEOMETRIC MEAN PRODUCTIVITY (GMP), tolerance (TOL), and yield stability index (YSI) were calculated based on grain yield under both with and without drought stress conditions. The results showed where irrigation cut off at anthesis, Kavir cultivar with 390.48 g/m2 had the greatest grain yield; while, under normal irrigation treatment the greatest grain yield was achieved from Shiroudi cultivar (873.83 g/m2). Comparison of MEANs under normal irrigation conditions showed that Ghods cultivar (57.7 grains per spike) and Yavarous cultivar (20.72 grains per spike) had the highest and lowest grains per spike, respectively. Under drought stress conditions, the highest and lowest grains per spike were obtained by Zarin (39.4 grains per spike) and Souraplata (9.9 grains per spike), respectively. In the present study, 1000- grain weight was significantly different between irrigation treatments. Sistan cultivar had the greatest (45 g) 1000- grain weight under normal conditions, and Omid cultivar produced the greatest (35 g) 1000- grain weight under terminal drought stress conditions. Comparison of the MEAN of wheat cultivars showed that highest grain yield was achieved under stress and non-stress conditions in Kavir and Derakhshan cultivars, respectively. The lowest grain yield under both conditions was obtained from Veernak cultivar. The results of this investigation indicated that GMP, STI and MP, which had the highest significant correlation with the grain yield under both conditions, were assigned as the most appropriate indices for evaluating the drought tolerance of cultivars.

Wheat grain yield reduction occurs in most wheat growing regions of Iran due to post-anthesis water stress. This research was conducted to evaluate yield and yield components of wheat cultivars in normal irrigation and post anthesis irrigation cut-off conditions as a split-plot arrangement based on a randomized complete block design with three replications during 2015-16 in College of Agriculture, Shiraz University, Shiraz, Iran. The main plots included irrigation regimes (normal irrigation until the end of the growth season and irrigation cut-off from flowering to maturity) and subplots composed of 20 bread wheat cultivars. The results showed that irrigation cut-off caused a significant reduction in biological yield (46.4%), grain yield (59%), harvest index (23.7%), number of grains per spike (27.1%) and 1000 grain weight (13.8%).The highest grain yield in normal irrigation (1002 gm-2) and post anthesis irrigation cut-off conditions (485.7 gm-2) was obtained from Danesh cultivar. Among indices, stress tolerance index (STI), MEAN PRODUCTIVITY (MP), and GEOMETRIC MEAN PRODUCTIVITY (GMP) had positive and significant correlations with grain yield in stress and non-stress conditions.Therefore, it appeared that these indices might be suitable for identification and selection of wheat cultivars that are tolerant to post anthesis irrigation cut-off. In general, the results indicated that Danesh, Sirvan, Baharan, Jones and Symonyda cultivars out–yielded the remaining ones under both stress and non-stress conditions.

Breeding and release of high yielding and drought tolerant varieties along with advance agronomic practices are effective ways to manage drought and water deficit in agriculture. This experiment was conducted in order to identify tolerant genotypes to drought and evaluation of main characters and drought resistance indices on 20 bread wheat genotypes (18 promising  lines and 2 checks, Sardari and Azar-2) during three cropping seasons (2002-2005) in two locations, Kermanshah province, Sararood station (moderate cold area) and Maragheh, Maragheh station (cold area). The genotypes were evaluated in a RCBD design fashion with four replications. Simple and combined analyses of variance for three years were carried out. The results showed significant differences among genotypes in different irrigation application. The highest grain yield, yield stability, and drought tolerance were belonged to the genotypes nos.1 (14 Gene Bank Material), 2 (914 Gene Bank Material), 4 (F9.10/May"s"//Sabalan), 19 (Sardari), 20 (Azar-2), 3 (Turkey 13//F9.10/Maya"s") and 14 (Fengkang15/Sefid), under different irrigation scheme. Evaluation of stress tolerance indices i.e. stress tolerance index (STI), GEOMETRIC MEAN PRODUCTIVITY (GMP) and MEAN PRODUCTIVITY (MP) also showed the superiority of the above mentioned genotypes. Evaluation of different stress tolerance indices indicated that STI is a general index which can be used as selection criteria in breeding programs.

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In order to study and evaluate drought stress indices on yield, grain yield components, oil yield, seed oil percentage and sesame grain water use efficiency, a field study was carried out as split plots in randomized completely block design with three replications in 2018-2019 in Behbahan Agricultural Research Station. The main factor was the amount of irrigation water at four levels (40, 60, 80 and 100% of crop water requirement) that was applied by drip irrigation system since the beginning of flowering stage and the sub factor was sesame varieties including Darab1 and Dashtestan2 cultivars. The average applied water in 40, 60, 80 and 100% of crop water requirement treatments and also in control treatment (surface irrigation) were measured to be 350, 414, 478, 542 and 651 mm, respectively. The comparison of average water use efficiencies in different treatments of sesame seeds) for Darab1 cultivar with 100% crop 3showed a high value (0. 240 kg/mwater requirement, identifying as superior treatment. Also, the results of Pearson correlation coefficient showed by increasing plant height, number of seed in capsule, number of capsule per plant, 1000-seed weight, volume of applied water, the seed oil yield and water use efficiency increase. Finally, due to lower values of SSI and TOL indices and higher values of STI, MP and GMP indices in Darab1 variety compared to Dashtestan2 variety, Darab1 variety could be introduced as superior treatment in term of drought stress.

‎Suppose that $B_1,\cdots,B_m$ are positive operators on a Hilbert space $\mathcal{H}$‎. ‎In this paper we generalize the weighted arithmetic‎, ‎GEOMETRIC and harmonic MEANs as follows‎:‎\begin{align*}‎‎{\mathbf a_m}(\boldsymbol\kappa;\mathbf{B})&={\mathbf a_2}(k_1,N';B_1,{\mathbf a_{m-1}}(\boldsymbol\kappa';\mathbf{B}'))=\frac{k_1B_1+\cdots+k_mB_m}{N}\\‎‎{\mathbf h_m}(\boldsymbol\kappa;\mathbf{B})&={\mathbf h_2}(k_1,N';B_1,{\mathbf h_{m-1}}(\boldsymbol\kappa';\mathbf{B}'))=\left(\frac{k_1B_1^{-1}+\cdots+k_mB_m^{-1}}{N}\right)^{-1}\\‎‎{\mathbf g_m}(\boldsymbol\kappa;\mathbf{B})&={\mathbf g_2}(k_1,N';B_1,{\mathbf g_{m-1}}(\boldsymbol\kappa';\mathbf{B}'))‎‎\end{align*}‎‎where $\boldsymbol\kappa=(k_1,\cdots,k_m)‎, ‎N=k_1+\cdots+k_m‎, ‎\boldsymbol\kappa'=(k_2,\cdots‎, ‎k_m)$ and $N'=k_2+\cdots+k_m$‎. ‎We show that the arithmetic-GEOMETRIC-harmonic MEAN inequality holds‎. ‎Also we investigate nine property of the GEOMETRIC MEAN‎.