Identifying the constraining factors of production and yield gap is very important. Therefore; this research was performed to identify the production constraining factors of local rice cultivars. All management practices from nursery preparation to harvesting stages for 100 paddy fields of local rice cultivars were recorded through field studies, in Sari, from 2015-2016. In the CPA, the actual and calculated potential yield were 4495 and 5703 kg/ha, respectively and the gap was 1221 kg/ha. The yield gap caused by number of top-dressing variables was 324 kg/ha, equal to 27% of the total yield gap. The yield gap related to previous year of legumes cultivation was 218 kg ha-1, equal to 18% of the total yield variation. Among the 10 variables entered in the CPA model, the effects of top-dress fertilizer application and its application frequency and foliar application were remarkable, which could compensate a significant part of the yield gap (444 kg/ha, 37% of total) in the farmers’ fields by managing these variables. According to boundary line analysis (BLA) finding, actual yield mean on the basis of optimal limit related to 12 variables under study was 5369 kg/ha, with 881 kg/ha yield gap . Mean relative yield and relative yield gap for 12 variables (transplanting date, seedling age, number of seedlings per hill, planting density, nitrogen and phosphorous per hectare, nitrogen before transplanting, harvesting date, lodging problem, pest problem, diseases problem and weeds problem) were 83.64 and 16.35 kg/ha, respectively. Based on the finding, it can be stated that the model precision is appropriate and can be applied for both estimation of the quantity of yield gap and determining the portion of each restricting yield variables.

Background and objectives: It is predicted that at least 10 million people will be hungry and malnourished in the world by the end of this century. To reduce the food insecurity, crop production will have to be doubled, and produced in more environmentally sustainable ways. This can be achieved by expanding the area of crop production, increasing per hectare yield and improving crop quality. Furthermore, during the second half of the past century, rise in per hectare crop productivity was due to improved or high yield potential. The productivity of plants are strongly influenced by environmental stresses. In the water scarcity condition, using deficit irrigation and appropriate cultivar are the most strategies to improve water productivity. A new generation of dry-tolerant Forage varieties would allow for landscape development in stresses environments and where fresh water is limited or not available for irrigation. Hence, the present study was to design with the following objectives: To determine yield and morphogical parameters of quinoa (Chenopodium quinoa Willd.) and Forage sorghum) sorghum bicolor), verities at different levels of irrigation and plant densities.Materials and methods: A field experiment was conducted during 2015 and 2016 at Aghghala salinity station. The experiment was laid out in a randomized complete block design in form of factorial split plot factorial experiment and replicated four times. At this research effects of irrigation frequency at four levels (irrigation after 5, 10, 15 and 20 days), and plant density at three levels (11.1, 16.7 and 33.3 plants per m2) on quinoa (Santa Maria and Sajama Iranshahr) and verities of KFS3 and Speed feed sorghums were investigated. Sowing date was the time of soil temperature reaching to 12 °C and the harvesting date was the time of 5% flowering of each plot. For yield estimation, after removing borders, 6 m2 harvested. Data were analyzed using SAS. Treatment means were compared using LSD at the 95%probability level.Results: Results showed that, the difference in most treats between treatments was significant. Investigation of dry Forage yield at irrigation treatment showed, irrigation every 5 days interval with dry yield of 6.01 ton ha-1 had the highest yield and yield components of dry Forage. With increasing plant density and dicrasing irrigation frequency dry matter dicreased but this dicreasing mostly accurse at interaction affect of irrigation every 20 days interval and plant density of 333000 plant ha-1. Plant density of 11.12 plants per m2 with yield of 4.98 ton ha-1 had the highest yield. The suitable treatment was variety of Santa Maria at 11.1 plants per m2 with dry yield of 4.77 ton ha-1 had the highest dry yield and variety of Speedfeed sorghum at plant density of 33.3 plants per m2 with yield of 2.53 ton ha-1 had the less ranking.Conclusions: In all, in order to high quantitative yield irrespective of variety, most frequently irrigation had higher yield than less and intermediate irrigation regime. Though, when comparing the four varieties, quinoa (Santa Maria variety (significantly with dry yield of 4.42 ton ha-1 produced higher dry Forage yield. The present findings suggest that in semiarid environments (where saving water is important) it seems that incrasing irrigation frequency is effective for good stand establishment in the saline soils could be insured if proper management is applied in the farms.

The effect of fire on vegetation of semi-arid steppe has not been studied extensively. Wildfires are rare in some steppe rangelands because of high levels of large herbivore grazing. However, grazing is sometimes restricted or excluded in areas such as national parks or the areas where afforestation projects are conducted. Therefore, sometimes, wildfires occur during the dormant season when litter (the uppermost layer of organic debris on the soil surface; essentially the freshly fallen or slightly decomposed vegetal material) mass has resulted in peak levels. Our study assessed the effects of a single fire on litter mass, Forage production, and Forage crude protein, Neutral Detergent Fiber (NDF), and Acid Detergent Fiber (ADF) in high altitude rangelands of Eastern Anatolia. We found significant effects of treatment (fire and no fire), years, and sampling date on all variables. Following the prescribed fire in 2011, litter mass and Forage production was less in treated plots compared to untreated control plots during both years. The effect of the fire on litter and Forage production was more pronounced in 2012 compared to 2013. The effects of the fire on Forage quality variables were also greater in 2012 than in 2013. Forage crude protein levels were consistently higher in treated plots during all 2012 sampling periods. Similarly, NDF and ADF tended to be lower in treated plots relative to the control plots during 2012. All effects we found were more pronounced in the first growing season following the fire compared to the second growing season, suggesting a relatively transient nature of fire effects in the steppe vegetation we studied.

Direct biomass measurements such as clipping method is difficult, destructive and time consuming. This research was performed to study possibility of Sphaerocoma aucheri Forage production using some vegetative traits (such as cover characteristics including its area mean diameter, small diameter, large diameter and height of the plants). Dry Forage production and some independent variables were randomly collected, from 50 plants of S. aucheri in a 4 years enclosure sites in Hormozgan province. After eliminating the outlier data and conducting normal test, multi variables regression in SPSS package was used to analyses data. The results showed that 77% changes in dry biomass of the species can satisfactory be estimated using canopy cover data The coefficient of cover area and constant index in regression model were 3.192 and 6.283 respectively. Validated model revealed that Sphaerocoma aucheri dry Forage can be estimated properly measuring canopy cover of the species.

In order to detemine Forage production of clover speices in spring and fall plantings, an experiment was carrid out in randomaized compelet block desgin with three replications and twelve treatments in Karaj during 1999-2001.The results showed that dry matter yield mean of clover speices in three years of experiment, in autumn planting was higher than that in spring planting. The highest dry matter yield from years (1999-2001), 8.13 tha-1 and 8.67 tha-1 in spring and fall plantings respectively, belonged to persian clover cv. Alshtar. The combined analysis results showed that the effects of year, cultivar and interaction of year x cultivar for dry matter yield were significant at 5% level. The first cut in spring planting and second cut in autumn planting had the highest dry matter yields. In general, a trend of increase in dry matter yield of clover cultivars was observed from spring planting to fall planting. It was also cleared that persian clover cv. Alshtar with a mean Forage yield of 8.40 tha-1, a variance of 0.77 and a coefficient of variation of 4.6, had the highest yield and most stability among the cultivars.

The present study is conducted to separate the effective and influential management factors in the production of clover Forage in Iran and to identify its limiting factors. In this study, the data obtained from 68 research projects conducted by the Agricultural Research, Education, and Extension Organization (AREEO) throughout the country during the 2009-2020 years have been analyzed, using the meta-analysis method. The results show that planting date -3.31%, planting method -22.82%, species +40.14%, seeding rate (planting density) +1.53%, drought stress -16.16 %, and phenological stage of Forage harvesting -15.42% justify the amount of Forage clover variation. Thus, fall planting in the middle of September, basin planting method, choosing the Berseem clover species (Trifolium alexandrinum var. Karaj), the seeding rate of 15-20 kg ha-1 (for Forage production), and Forage harvesting at the phenological stage of 10-25% flowering, are the most important management and agronomic factors in increasing clover Forage production in cold and temperate regions, and not complying with one or a set of these factors will reduce the clover production and will cause yield gap. Overall, the species, planting method, and drought stress are respectively recognized as the most important factors affecting clover Forage yield in Iran.

Rangeland capacity depends on Forage produced in the rangeland, allowable use of plant species, Forage quality, and degree of rangeland health. Range species have a certain production in different months and years. It is not possible to plan and manage rangeland and livestock without knowing the production characteristics and Forage consumption of rangeland during the grazing period. This study was conducted in 2008-2010 years, and the Forage production and utilization rate was measured in different months and years. The annual precipitation were 138, 200, and 330 millimeters for three years, respectively. The results showed that total Forage production was significantly different between years (p<0. 01). Forage production was 485. 7, 1372, and 1844. 4 Kg per hectare, respectively. Also, there was a significant difference between (March to August), with 94. 7% of range production in the first two months (March and April), and 5. 3 % of remaining Forage production was in the last four months of the vegetative period. Therefore, Forage production during the growing season is not suitable. Other results showed that the amount of utilization in three years was 400, 751, and 490 kg / ha, respectively. Although the difference was not statistically significant, in the dry year 2008, 83 percent and in the wet year 2010, 26. 6 percent of Forage production was consumed. Thus, in the dry year, as Forage production declined, livestock utilization increased by 83%, which is not commensurate with range capacity. Other results showed that the share of annual and perennial plants in total range production was 81% and 19%, respectively, and the share of livestock diet was 90% and 10%, respectively. Therefore, in order to achieve sustainable production, proper management of rangeland and the use of native species such as Onosma bulbotrichum, Ankyropetalum gypsophiloides, Convolvulus reticulatus and Salvia compressa are recommended.

In order to investigation Forage production of annual medic Cultivars, under dryland farming conditions of Gorgan, an experiment carried out in Chaleki research station in 2003-2004. The experimental design was randomized complete block with 4 replications. Cultivars were Medicago scutellata cv.Robinson & sava, Medicago truncatula cv. Caliph & Mogul, M. sphaerocarpos cv. Orion sphere, Medicago polymorpha cv. Spinless, Medicago litoralis cv.Herald and an indigenous species (Medicago minima). Forage was harvested at %10 flowering and dry matter (DM) production was measured after shade drying. Results showed that, Forage production of cultivars were significantly different (P<0.01), also Interaction of cultivars and year were significantly different (P<0.05). Forage production of Medicago scutellata cv.Robinson (2006.4 kg/ha DM) was higher than other cultivars at the first year and Medicago truncatula cv. Caliph with 2230.1 kg/ha DM was produced the highest Forage yield at the second year.  Based on results, Mogul and Sava during two growing seasons with sustained Forage production relative to experiment conditions were more adaptable than other cultivars. The mean of Crude protein amount of Caliph (37.28 gr/mˆ2) was higher than other cultivars.