Changing rice cultivation system from puddle transplanting to Direct seeding greatly reduces labor and crop production costs. A field experiment was conducted at Rice Research Institute of Iran-Rasht in 2018 as split plot based on a randomized complete block design to evaluate the effect of seeding date and planting method on growth and grain yield of Hashemi cultivar in Direct seeding method. Main plots included seeding date (May 1, 8, 15, 22, 29 and June5 and 12) and sub plots were planting methods (broadcast seeding, row seeding and hill seeding). Moreover, transplanting plots were included to the experiment as control treatment. Analysis of variance showed that seeding date had significant effects on paddy yield but planting method and their interaction had no significant effect on paddy yield. Maximum paddy yield were recorded at the dates of 1 and 15 May (4414 and 4325 kg ha-1, respectively). Paddy yield was significantly reduced when seeding date delayed, as grain yield reduce by 41%, 43%, and 70% at the seeding dates of 22 and 29 May, and 5 June compared to the seeding date of 1 May. There was no significant difference in paddy yield between Direct seeding (4295±215 kg ha-1) and transplanting (4414±184 kg ha-1) production systems. Moreover, seeding date and planting method had no significant effect on weed biomass. In general, result revealed that optimum paddy yield in Direct seeding was recorded at the seeding date of 1 and15 May.

Due to the dependency of Direct seeding of rice on the application of herbicide and possibility of weed resistance to herbicides, the use of mixtures of herbicides is of considerable importance. To evaluate the effectiveness of consecutive applications of some herbicides with lower concentrations, including Thiobencarb, Pretilachlor, Bensulfuronmethyl, Ethoxysulfuron+Anilofos, Butachlor, and Propanil, on weed density, yield and yield components of rice (Oryza sativa L. cv. Hashemi) an experiment based on a randomized complete block design with eight treatments and three replications was conducted at the Research Farm of Faculty of Agricultural Sciences, University of Guilan in 2014. The results showed that plant height, seed yield, dry matter yield, harvest index, number of tillers and number fertile florets per panicle were affected by these treatments. Tandem use of Thiobencarb (9 day before sowing), Bensulfuronmethyl (9 day after sowing) and Propanil (30 day after sowing) affected weed dry matter and weed density by 92 and 98 %, respectively. The highest number of fertile floret per panicle (71 pcs) and tillers number per plant (14 pcs) were observed in plots where Thiobencarb, Bensulfuronmethyl and Propanil were used consecutively. In this treatment, seed yield and biological yield increased by 72 and 73 percent respectively as compared with that of control. Application of Pretilachlor caused phytotoxicity, where by reduced plant height and seed yield. The highest grain yield of rice (3092 kg.ha-1) was produced by consecutive use of Thiobencarb, Bensulfuronmethyl and Propanil. This treatment was more effective in reducing density of weeds and their dry matters than of two times hand weeding. The use of Thiobencarb followed by Bensulfuronmethyl and Propanil was the most effective treatment in this expriement.

The main method of rice planting in Iran is transplanting. Due to poor mechanization of rice production, this method is laborious and costly. The other method is Direct seeding in wet lands which is performed in the one third of rice cultivation area of the world. The most important problem in this method is high labor requirement of weed control. In order to compare the different rice planting methods (Direct drilling, transplanting, and seed broadcasting) a manually operated rice Direct seeder (drum seeder) was designed and fabricated. The research was conducted using a randomized complete block design with three treatments and three replications. Required draft force, field efficiency, effective field capacity, yield, and yield components were measured and the treatments were compared economically. Results showed that there were significant differences among the treatments from the view point of rice yield at the confidence level of 95% i.e. the transplanting method had the maximum yield. A higher rice yield was obtained from the Direct seeder compared to the manual broadcasting method but, the difference between these two methods for crop yield was not significant even at the confidence level of the 95%. The coefficient of variation of seed distribution with Direct seeding was more than 20%. The labor and time requirements per hectare reduced to 7 and 20 times, respectively when comparing the newly designed Direct seeder with the transplanting method. The Direct seeding method had the highest benefit to cost ratio in spite of its lower yield. Therefore, this method could be recommended in the rice growing regions.

Introduction: In Golestan province, despite the lack of water resources, traditional rice cultivation, a crop with high water consumption, is increasing due to economic justification. This issue has become one of the main problems of the province's agricultural sector in recent years. In order to prepare the planting bed (puddled transplanting) in the traditional method of rice production, a significant amount of irrigation water is used before planting the seedlings in the main land. Moreover, the plant is in the water during the growing season, which causes high water losses by surface water evaporation and deep penetration. Rice Direct seeding cultivation is a method that has been considered in the world for various reasons, including higher water productivity. Currently, reports indicate that more than 50% of groundwater resources are extracted and allocated annually for rice cultivation in the region investigated. In general, field information and observations indicate that the level of paddy cultivation is increasing in the province. In the past few decades, agricultural policymakers have sought to restrict and ban rice cultivation in the country, except in Gilan and Mazandaran provinces. The rationale behind this decision is high water consumption, declining groundwater aquifers and long-term instability of water resources. The developed strategy did not work effectively, as it did not consider the benefits of the farmers in the short run. The increasing trend in the area under paddy fields from 1995 to 1500 hectares per year shows the unsuccessfulness of this up-to-down strategy. Materials and Methods: A field experiment was conducted to investigate the effect of rice cultivation and irrigation methods on yield, water consumption and water productivity over two rice cropping seasons (2019–,2020) in northern Iran (Gorgan Agricultural Research Station). Irrigation method as the main factor in four levels (permanent flooding, intermittent as wet and dry, sprinkler, tape) and cultivation method in three levels (Direct seed in dry bed, non-puddled transplanting and traditional transplanting) in the form of a strip design. The plot was based on a randomized complete block design with three replications. The applied water, yield and some yield components and water productivity were measured and calculated during the growing seasons. Results and Discussion: The results showed that in all irrigation methods, yield was significantly reduced by changing the traditional seeding transplanting to dry seed. The amount of water applied in sprinkler and drip irrigation methods from traditional seedlings was significantly reduced as compared to Direct seed seeding. Dry seed cultivation, however, consumed more water than traditional transplanting in the flood irrigation treatments (wet and dry and permanent). The highest yield (8206 kg/ha) was obtained for traditional seedling cultivation by flood irrigation, and no significant difference was observed between the yields for the other irrigation methods. In general, changing the irrigation systems had a greater effect on water consumption than changing the rice cultivation method. In addition, changing the cultivation method had a greater effect on changing the type of irrigation systems. In traditional transplanting cultivation, the yield decreased by about 14, 9 and 11%, respectively, by changing the irrigation systems from permanent flood irrigation to sprinkler, wet and dry, and drip irrigation. The highest water use was observed for flood irrigation method in Direct seeding (12490 m 3 /ha) and Direct transplanting (11967 m 3 /ha). Conclusion: Currently, farmers cultivate rice by transplanting in padded land irrigated by flooding techniques in Golestan province, which results in high water consumption (about 13, 000 m 3 /ha). By changing the irrigation method from flood irrigation to drip for traditional transplanting cultivation, water consumption decreased by about 39% and as a result water productivity increased by about 22%, albeit a 11% reduction in yield occurred. With the conversion of traditional transplanting seedling by flood irrigation to non-puddled transplanting by drip irrigation, the yield decreased by about 24% and the amount of water by about 45%, and water productivity in this case reached 0. 9 kg/m 3. This can be considered as the best alternative for conserving both water resources and production. If only reducing water consumption is the main priority (regardless of yield reduction), the best treatments are drip irrigation with Direct seeding, non-puddled transplanting and then traditional seedling, respectively. If there is a sprinkler irrigation system in the field, this option is given priority in the Direct seeding and non-puddled transplanting. If changing the irrigation system is not considered, the use of intermittent irrigation (as a wet and dry) with non-puddled transplanting, traditional methods and Direct seeding are preferred, respectively.

This study was carried out in 1996 in orther to compare yield and other traits in rice cultivars under Direct seeding and transplanting methods at Joneghan region of Chaharmahal and Bakhteyari province. Genotypes were composed of three selected lines (4 ,30 and 65) from local breeding populations, varieties 24IRCTN90 and Gerdeh Joneghan local variety. In this investigation 2 factors were compared in a factorial experiment with 3 replications. One factor consisted of 5 lines and cultivars and another factor consisted of 2 planting methods. Planting time in both the Direct seeding and transplanting methods were the same. Harvest time both in this experiment and in the region was also the same. Results indicated that all cultivars had lower yield than local variety under Direct seeding method and their growing period could be not completed. The yield under transplanting was higher than Direct seeding method in all of the cultivars. Line 65 showed the highest yield (54ookg/ha) under transplanting method. In Direct seeding, the performance of other traits was significantly less than transplanting method.

To investigate the effect of planting dates on agronomy traits of rice varieties in Direct seeding, an experiment was carried out at Randomized Complete Block Design based on split plot with four replications in Mazandaran province during 2009. Main factor was planting date in four levels (28 Apr, 7, 16 and 25 May) and sub factors were varieties in three levels (Shirudi, Amrollahy Tarom and Hashemi Tarom). Results showed that, planting date had significant effect on plant number, fertile tiller number, panicle number per m2, filled grain percentage per panicle, 1000 seed weight, harvest index and grain yield. Meanwhile cultivars had significant effects on all the mentioned traits. In general, among cultivars, Shirudi had the highest grain yield because of the high plant number, fertile tiller number, panicle number and harvest index, while Hashemi Tarom because of the low fertile tiller number, 1000 seed weight and harvest index had less grain yield. Maximum grain yield was produced in planting dates 7th and 16th of May, respectively, and minimum grain yield in 25th May planting date. Among the mentioned traits, panicle number per m2 and harvest index had the highest correlation with grain yield. Interaction effect planting date in a variety of studies (except full spikeletes percent ) showed significantly affected from which the highest yield belonged to 7th and 17th of May planting date of Shirudi cultivar.

To investigate the effect of seed priming on emergence characteristics, root morphological growth, and phenological trends of rice in Direct seeding, an experiment has been conducted in Sari Agricultural Sciences and Natural Resources University within 2019. The study is conducted as factorial in a randomized complete block design with three replications. The factors include Tarom Hashemi and Shiroudi cultivars and priming at five levels, namely hydropriming (for 48 hours), calcium chloride, and potassium chloride priming (Ψ s-1. 25 MPa), ascorbate acid (10 mg l-1), and control (no priming). The effect of priming on emergence percentage shows that the highest amount of this trait belongs to 90% in priming with calcium chloride, which is not significantly different from priming with potassium chloride and water. The rate of emergence of priming with calcium chloride, potassium chloride, and water has increased by 50%, 36%, and 29%, respectively. Results show that priming with calcium chloride, potassium chloride, ascorbate acid, and water has increased by 55%, 50%, 33%, and 38% of the plant height and by 48%, 29%, 12%, and 25% of plant dry weight, respectively. In Shiroudi and Tarom Hashemi cultivars, the time required for the onset of tillering has been 27. 40 and 24. 53 days; panicle appearance, 90. 4 and 53. 87 days; flowering, 100. 53 and 70. 87 days; and maturity 132. 26 and 94. 61 days, respectively. The least time required for panicle appearance and flowering is observed in priming with calcium chloride, although this has not been significantly different from other priming, and decreased by 11. 17 and 7. 5 days to the control, respectively.

The present study was carried out with considering the problem of Quecus castaneifolia (C.A.Meyer) natural regeneration in Caspian forests and the key rule of light and vegetation competition (with dominant species of grass) in growth and establishment. For this target, homogenous, sound acorns were collected from a mature tree and Directly sown in an open area of Caspian plain forest, Noor region (15 m a.s.l.). The experimental design was based on factorial and completely randomized blocks with cleaning treatment (weed removal, weed competition or control) and light treatment (full light and 40% shade). To make a shadow, the wooden network with 100 cm in height was applied. Results at the end of third growth season revealed that under weed competition, height growth, collar diameter and number of branches of Q. castaneifolia seedlings were significantly decreased but survival did not differ. With increasing light intensity, number of branch was significantly increased, but no significant difference obtained in survival rate, height growth and collar diameter growth. Survival did not decrease from 86.4% in competition with weed and from 90.6% in full light. It is deduced that growth and establishment of Q. castaneifolia in open areas, like in shaded places, has been successful. So, it can be suggested that Direct seeding of Q. castaneifolia is a suitable method for restoration of degraded and non-regenerated areas in some lowland forests of northern Iran. In these conditions to reduce competition in early years it is better to use weeding practices around the seedling following Direct seeding.