Various poplar varieties have different needs and requirements and different water supply and intervals can change their growth conditions, significantly. Due to limited water resources at most parts of Iran, irrigation interval is more important than irrigation volume in conventional and industrial poplar plantation systems. The aim of the study was to investigate the quantitative and qualitative growth characteristics of different poplar varieties at various irrigation regimes and identify the best irrigation interval. For this reason a trial was conducted in Karaj City of Iran under experimental design of split plots at three replicates. The main plots consisted of three irrigation intervals (4, 8 and 12 days) and the subplots consisted of nine poplar clones. The water supply at each irrigation interval was equal and there were nine seedlings at each subplot at 3 X 3 m. spacing. Irrigation regime for all treatments at first year of trial was similar. The irrigation treatments were supplied at the second year of the trial and an equal water supply was applied to all irrigation treatments, using flume model W.S.C. type3 at each water supply resource and measuring water dimension and time pass of each flume and application of standard curves.The measured poplar growth characteristics consisted of dbh, total height, stem height, crown diameter, stem volume, morphology and phenology. The results showed that there was only significant difference between the both 4 and 8 and the 12 day irrigation intervals in respect to growth parameters. Although there was no significant difference between the 4 and 8 day intervals in respect of growth parameters, but water consumption at the 4 day interval was 7500 m3 more than that of the 8 day interval. All the poplar clones had intensive growth reduction at the 12 day interval irrigation regime and it might be concluded that this irrigation interval is not appropriate for poplar wood production. The poplar clones of P.n. 62/154, P.e. 561/41 and P.e. vernirubensis had the best growth performance at the 4 and 8 day irrigation intervals.

This experiment was conducted in Khosheh Sabz Sonboleh Institute in Fasa during 2007-2008. In this study Isabgol (plantago ovata Forsk.) yield reaction and quality characteristics of irrigation intervals and different levels of nitrogen were studied. Completely random design with 3 replications was used. Factors included 3 irrigation intervals (7, 10 and 14 days) and 3 nitrogen levels (0, 30 and 60 kg). Variance results showed that variations of grain yield, biological yield and mucilage yield were significant. Drought intensity also increased percentage of mucilage yield significantly. The best economic and biological quality was obtained by short irrigation interval. In long irrigation interval, two characteristics showed significant decrease, but against biological yields, they showed increased trend. Therefore, with increased amount of nitrogen, economic yield, biological yield and mucilage were increased. Grain and biological yield in drought stress condition in long irrigation intervals showed less response than increasing nitrogen levels.

In order to investigate the effects of different irrigation intervals on morphological characteristics of different Achillea millefolium L. populations, an experiment was conducted at the experimental field of Research Institute of Forests and Rangelands during 2012 and 2013. Three irrigation intervals (7, 14 and 21 days) and 19 A. millefolium populations were compared in a factorial experiment based on a complete randomized block design with three replications. As many plants were lost in irrigation interval of 21 days, comparison was continued with irrigation intervals of 7 and 14 days. Results showed that irrigation intervals and population origins had significant effects (P≤0.005) on the plant height, crown diameter, stem number, dry matter yield (g plant-1), flower diameter, flower number and flowering time. In almost all populations the plant height, crown diameter and flower diameter decreased, whereas flower number per plant and the full flowering time increased in irrigation interval of 14 days. The 19 populations were grouped into three clusters. Populations in the cluster I had higher plant height, yield and flowering time. Populations in the cluster III showed higher crown diameter, flower diameter, stem number and flower number, and shorter full flowering time. These results indicated that populations in the cluster III had favorable potential production in semiarid regions.

Introduction Guar (cluster bean) Cyamopsis Tetragonaloba is one year plant belongs to the leguminous family. Guar has high nutritional value for humans. Global demand for guar has increased dramatically in recent years, which has led to the introduction of the plant in several countries. Water stress is the most important factor limiting planting and reducing food crops, especially in arid and semi-arid regions of the world. Therefore, identification of resistant plants and mechanisms that lead to optimal water use and high crop yields are critical. Given the limited water resources in the country, the evaluation of guar stands under drought stress is of particular importance. Materials and Methods The experiment was carried out at the Research Farm of Iranshahr Agricultural and Natural Resources Faculty in 2017-18. The experiment was conducted as a split-plot in a randomized complete block design with three replications. Three levels of irrigation interval (7, 5, and 9 days) and six guar stands (Sarbaz, Saravan, Iranshahr, RGC1033, Indian, and Grembit) were considered as main and sub-factors, respectively. After planting in the 5-leaf stage, the stress operation began and continued until the seeds were harvested. At the end of the growing season, samples were transferred to the laboratory and shoot length and root length, fresh and dry weight of shoot, fresh and dry root weight, number of branches, 100 seed weight were measured. Leaf chlorophyll index was measured using Spad 502 Minolta chlorophyll meter. The chlorophyll fluorescence was measured using a Handy-PEA portable fluorometer (Hansatech Instruments). Finally, statistical analysis was performed using SAS software and mean comparisons were made using the LSD test at 5% probability level. Results and Discussion Increasing irrigation intervals significantly decreased plant height in Sarbaz and Saravan. The results showed that at 9-day irrigation period, the highest plant height (77. 5 cm) was related to RGC1033 which did not show any significant difference with Saravan. The lowest plant height (42. 03cm) was related to Sarbaz ecotype. Results showed that the 9-day irrigation interval increased root length in RGC1033, Iranshahr and Sarbaz and significantly reduced root length in Indian ecotype. The results showed that in 9-day irrigation period the number of branches in Iranshahr and Grambit decreased but increased in Saravan and RGC1033 genotypes. While the irrigation interval had no effect on Sarbaz ecotype. Most of the branches were 5. 7 in RGC1033 ecotype. The Indian ecotype lacked a branch at all irrigation intervals. At 9-day irrigation period, Saravan and Iranshahr had the highest leaf dry weight. In Iranshahr and RGC1033 genotype, fresh and dry weight increased. Increasing irrigation interval resulted in a significant decrease in the dry weight of Indian root. The irrigation period had no significant effect on Saravan and Grambit ecotypes. Increasing irrigation intervals did not have a significant effect on the Sarbaz, Grambit, and Indians. With increasing irrigation intervals in RGC1033, Saravan and Iranshahr dry weights increased. The simple effect of ecotype type on seed weight showed that Saravan, Indian, and Iranshahr had the highest seed weight, respectively. Whereas, the SG, RGC1033, and Grambit had the lowest seed weight without any significant differences together. Saravan ecotype at all irrigation levels showed more biological function than other ecotypes. Results showed that the harvest index decreased with increasing irrigation intervals. In the 5-day irrigation treatment, the Grambit and Saravan ecotypes had the highest and the lowest harvest index, respectively. The 9-day irrigation period significantly reduced Fv/Fm in Sarbaz, Grambit, and Iranshahr. RGC1033 and Indian populations had the highest Fv/Fm in leaves and Saravan and Iranshahr had the lowest Fv/Fm in leaves at 7 days irrigation period, respectively. The number of pods per plant, number of lateral branches, 100 seed weight and plant height have a direct and positive effect on guar yield. Under drought stress, plant height and leaf number decrease, resulting in lower shoot dry weight. Some researchers showed that decreasing plant height under water stress is associated with loss of protoplasmic water, resulting in reduced cell division and development. The harvest index decreased with decreasing number of pods, thereby reducing economic yield. Differences between susceptible and resistant ecotypes appear in high-stress conditions and high Fv/Fm ratio ecotypes have higher photosynthetic efficiency under severe stress conditions. Chlorophyll fluorescence is considered as a criterion for assessing the integrity of the thylakoid membrane in the relative efficiency of electron transfer from Photosystem II to Photosystem I. Conclusion Mean root length, the number of branches, fresh and dry weight of RGC1033 were not affected by a 9-day irrigation interval. In the 9-day irrigation period, the highest mean dry weight of leaf, main stem weight and seed weight were related to Saravan ecotype. The highest biological yield was observed in the irrigation period of 7-day and Saravan ecotype. In general, the results showed that irrigation had different effects on different guar populations. RGC1033 and Saravan ecotypes showed the lowest percentage of stress-affected variations.

In order to identify the correlations and relationships between different traits in the bread wheat, 30 genotypes were investigated as sub-factors under the split plot experiment in the completely randomized design in greenhouse and the randomized complete block design in the field with three replications under the normal irrigation and post-anthesis water stress conditions. The results of the canonical correlation analysis showed that at both normal and moisture stress levels, there was a significant correlation between the pair of canonical variables obtained from the phenological traits and the yield components. Under the normal conditions in the greenhouse, to increase the spike density and length, the number of days to 50% flowering can be considered as a suitable selection criterion. According to the results of canonical correlation analysis, under the stressed conditions in greenhouse, to increase the spike length, the number of days to the heading, maturity and 50% of flowering were among the important and effective factors. Under the optimum irrigation conditions in the field, the number of days to maturity was considered as one of the factors influencing the seed weight per spike. The results of canonical correlation analysis under the field stress conditions showed that to increase the 1000-seed weight, the number of days to maturity can be considered an appropriate selection criterion.

To evaluate the effect of irrigation intervals and different mulches on some traits of gladiolus cv. Rose Superme, an experiment was carried out as factorial arrangement in randomized complete block design with three replicutions in 2007-2010 growing seasons at Varamin Agricultural Research Center, Varamin, Iran. Experimental factors included: three levels of irrigation intervals; 7, 10 and 15 days and five mulches; no mulch, white plastic, wheat straw, pine dry leaves and black plastic. Plant height, spike length, floret number, flower diameter, corm diameter, corm and cormels weight were measured and recorded. Results showed that irrigation interval × mulch interaction effect was hightly significant (P < 0.01) on floret number, corm and cormels weight, and cormel number. Growing season also significantly (P<0.01) affected all traits except corm diameter. In conclusion, irrigation at 10 days interval with black plastic mulch can improve quantity and quality of gladiolus production.

Due to the climatic conditions of Iran, increasing water scarcity, and the effect of drought stress on the efficiency of irrigation water consumption and chemical fertilizers application, an experiment was conducted to investigate the effect of irrigation intervals (6, 9, and 12-day intervals), different levels of nitrogen fertilizer (200, 300, and 400 kg urea per hectare) and cultivation methods (on-ridge or heeling up and in-furrow) on yield and productivity of sugarcane as a factorial design based on randomized complete block design in 3 replications at Hakim Farabi Agro-Industry Company in Khuzestan province. The results showed that the maximum (106.73 tons/ha) and minimum (59.10 tons/ha) sugarcane yields were observed in 9-day and 12-day irrigation intervals, respectively. Also, the highest sugarcane yield (99.89 tons per hectare) was obtained in the treatment of 400 kg urea per hectare and the in-furrow planting method resulted in a higher yield compared to the on-ridge planting method. The highest water productivity in sugarcane stem yield and sugar production with 3.55 and 0.34 kg per cubic meter of applied water, respectively, was obtained in a 9-day irrigation interval. A significant increase in water use efficiency in sugarcane stem yield was observed in 400 kg urea/ha compared to the other two fertilizer levels. However, there was no significant difference in water productivity of sugar yield between different fertilizer treatments. The results showed that 6 and 9-day irrigation intervals in most of the studied traits were not significantly different. Therefore, using a 9-day irrigation interval is suggested in the studied area when the sugarcane cultivation area is high and the amount of available water is limited. In-furrow planting method can also be effective in reducing water consumption. Therefore, deficit irrigation and proper nitrogen fertilizer consumption can be very effective in sugarcane cultivation.

The present pot experiment was undertaken to investigate the phytoremediation potential of corn and oat in soil. Treatments consisted of four cadmium (Cd) levels (0, 5, 10 and 20 mg l1) and three irrigation intervals (1, 3 and 7 days), arranged in the form of a complete randomized design with three replications. Corn and oat were harvested after 75 and 90 days, respectively. Transpiration rates, shoot dry weight and shoot Cd concentration of both plants were measured. Cadmium uptake, Cd bioconcentration factor (BCF), the apparent recovery of Cd and water use efficiency were also calculated. Cadmium had negative, and in some cases stimulating effects on plant growth. Furthermore, the phytoremediation capacities of both plants were higher at the 1 day irrigation frequency. The BCF values for both plants were less than unity, indicating that the phytoremediation potentials of oat and corn were low in this study. Overall, oat was more efficient than corn in phytoremediation of Cd as it accumulated 52, 169 and 132% more Cd than corn at 1, 3 and 7 day irrigation intervals, respectively. On the average, oat also took up soil Cd about 80% more than corn. From the results reported herein, it is recommended to conduct additional experiments with different Cd levels and more irrigation intervals using different types of agronomic and horticultural crops.

The water deficiency is one of the serious problems in the arid zones. In order to investigate the effect of Cycocel on different growth aspects of two olive cultivars (Mary and Mission), a greenhouse experiment was conducted using three factors of: cycocel at three levels (0, 500 and 1000 mg L-1), irrigation of three levels (irrigated at 5, 10 and 15 days intervals) and tow olive cultivars (Mary and Mission) in a factorial experiment based on randomized complete block design of three replicates for the lasted four months. The results showed that both cycocel treatments decreased plant height, increased root length and number of lateral shoots; but no significant difference in stem diameter, leaf numbers, total lengths of lateral shoots, fresh weight of stem and root, chlorophyll b and carotenoid content was observed compared with control. High cycocel level (1000mgL-1) increased fresh weight of leaf and chlorophyll a content than the control. Also, results showed that increased periods of drought have reduced the plant height, stem diameter, leaf numbers, number of lateral shoots and total lengths of lateral shoots, root length, fresh weight of leaf, stem and root, increased chlorophyll a+b and carotenoid content in both cultivars. In above-mentioned parameters Mission cultivar showed higher resistance to drought stress than the Mary cultivar. Results suggested that Cycocel treatment can alleviate some negative effects of drought stress in Mary and Mission cultivars of olive.