gh. mohsen abadi

Rice-duck cultivation is an integrated farming technology, which could increase rice production, grain quality and ecological sustainability in paddy fields. One of the main strategies in sustainable agriculture is the use of optimal cultivation systems in agricultural systems which could be increased the range of adaptation of rice to flooding depth and degree of moisture control. Rice-duck cultivation could be affective to weed control as well as reducing environmental pollution which caused by herbicides and providing the development of environmentally friendly agriculture. It should be noted that traditional and conventional cultivation systems have been faced with problems such as permanent flooding of paddy fields, soil erosion, resistance to pests and pathogens and weeds to chemical pesticides, and environmental pollution. Moreover, they require a lot of labor and water, and high energy, which has increased the need to pay attention to new approach. Studies have showed that the application of effective methods in water productivity, including SRI due to improved irrigation management in the field in terms decreased drainage water, permeability and the consequences of conventional cultivation and increasing soil fertility (duck) can significantly increase the water productivity. The aim of this study was to investigate the effect of duck application and weed control in different planting systems on yield and abundance of dominant weeds under field conditions.

The experiment was conducted as a split plot factorial in a randomized complete block design with three replications during two years of 2017-2018 and 2018-2019 at Guilan University. Treatments included three different cultivation systems (conventional, improved, and SRI) as the main factor, and factorial combination of two duck density (un-use and 750 No ha-1) and three weed control (control (un-weed control), once and twice of weed control) as the sub factor. The experiment had three replications and the length of each plot was 4.5 meters and the width was 4 meters. In order to carry out the experiment, first plowing in the land to a depth of 20 to 25 cm with a rotator and paddling with a tiller was done according to the custom of the farmers of the region. In all plots, 80% of the recommended fertilizer was applied in SRI system after deducting the values of cow.

The results showed that abundance and dry biomass of weeds (Umbrella sedge, Barnyard grass, Knot weed and Arrow leaf) were significant in terms of planting system. In all planting systems, 750 ducks ha-1, once and twice weed control, caused complete loss of ovaries, Umbrella sedge, Barnyard grass, Knot weed, and Arrow leaf due to ducks' non-use conditions. 750 ducks ha-1 compared to un-use duck in conventional, improved and SRI planting systems increased grain yield of 21.61, 20.80 and 30.84%, respectively. Also, the application of 750 ducks ha-1 in compared to the conditions of un-used of duck in the cultivation systems of conventional, improved and SRI, increased by 34.80, 33.01, and 38.69% of water productivity, respectively, while there was no significant difference between different levels of weed control in the 750 ducks ha-1 in terms of water productivity.

In general, duck increased plant growth, improved power of rice and finally increased rice yield by proper weed control in the field with muddy water and beak, as well as adding rubbish to the paddy field. According to the results of this study, probably do once the initial hand weeding to control dominant weeds in SRI rice cultivation system with 750 ducks ha-1 to improve rice production systems and to increase water productivity in fields of Guilan province is appropriate.

In order to evaluate the effect of seed priming on lodging-related characteristics in direct seeding method, a study was conducted in a factorial randomized complete block design with four replicates in the research field of Rice Research Institute of Iran (Rasht) for two years. The first factor consisted of two rice cultivars (Khazar and Hashemi) and the second one consisted of ten levels of seed conditions encompassing, eight priming treatments including hydropriming, ascorbic acid, salicylic acid, CaCl2, cold, cold heat, seed coating, and non-primed dry seed, all sown with seed tap technology along with linear direct seeding of germinated seeds and transplanting (25-days-old seedlings). Agronomic and morphological characteristics and resistance to lodging indices were measured. The results showed that there were significant differences between two cultivars and ten levels of seed conditions in morphological traits and lodging resistance indices. Mean comparisons and correlation analyses showed that grain yield (5142 kgha-1), resistance to fracture in third and fourth internodes (549 and 704 Newton, respectively) in Khazar were higher than those of Hashemi. There was a significant difference between planting methods (direct-seeded and transplanting) in terms of lodging resistance. Maximum indicators in the third and fourth internode bending momentum (1060 and 1708 gcm-1) were observed in the transplanting method. Hydropriming treatment had significant effect on fourth internode thickness in cultivar Khazar. Priming treatments appeared to leave significant effect on resistance to lodging in different planting methods in a cultivar-specific manner.

This experiment was conducted in the Research Farm of the Faculty of Agricultural Sciences, University of Guilan in 2010 as an RCBD based split plot experiment with three replications. In this experiment five different amounts of soil moisture (Irrigation after depletion of 45, 55, 65, 75 and 85% of field capacity moisture) and two soybean cultivars (Gorgan-3 and Williams) was considered as main and sub plots, respectively. Results of ANOVA showed that moisture regime by cultivar interaction had significant effect on seed yield, number of pods per plant, number of seeds per pod and seed oil percent. Mean comparisons revealed that increasing soil water depletion resulted to decrease in seed yield, number of pods per plant and number of seeds per pod. Also, it resulted to decrease in grain yield of both cultivars, which was approximately 63% for Gorgan 3 and 2% for Williams. However, maximum (1667kg/ha) and Minimum (384kg/ha) seed yield were recorded for Gorgan 3 and Williams in 45% and 65% soil moisture regimes, respectively. The highest seed oil percentage was recorded for cultivar Williams which grown in 75% soil moisture while the lowest was for Gorgan 3 which grown in 55 % soil moisture regime. Seed protein also was affected by soil moisture regime, significantly with the highest (22.49%) and lowest (22.04%) in 55 and 85% soil moisture regimes, respectively. In this experiment Williams had low sensitivity index and high tolerance index while Gorgan 3 had high geometric mean productivity and mean productivity. Overall, Gorgan 3 had the highest seed yield in all soil moisture regimes. Its yield reduction percent was greater in drought stress prone treatments, in comparison with cultivar Williams which shows greater seed yield stability of the indeterminate Williams cultivar.

In order to study of sowing date and plant density on Triticale (Tritico secale), a field experiment was carried out under dry farming in the Rice Research Institute of Iran, during 2008-2009. The experiment was conducted as a RCBD based split-plot design with three replications. Experimental treatments included: Four sowing date (Sept. 21, Oct. 1, Oct. 10, and Oct. 20) as main plot and four plant density (275, 350, 425 and 500 plant/m2) composed of as sub plots, respectively. Results indicated that plant density was significant effect on tiller number/plant. The highest number (13.6 tiller/ plant) was obtained in 275 plant/m2 seed density. The results showed, spike length and plant dry matter was affected only by sowing date. The highest dry matter and the longest spike were produced on Sep. 21. Result of the experiment revealed that grain yield, spike number per plant and harvest index significantly affected by sowing date× plant density interaction. However, planting 500 plant/m2 in Sept. 21 resulted to highest (5863 Kg ha-1) grain yield and 275 plant/m2 seed in Oct. 21 resulted the lowest (3351.08 Kg ha-1).

In order to investigate effect of deficit irrigation on phenological stages and yield of soybean cultivars, an experiment was conducted as split plots based on randomized complete block design with three replications at Agricultural Research Farm, University of Guilan in 2009. Main factor was included four irrigation levels based on potential moisture 30-35 (I1), 50-55 (I2), 70-75 (I3) centibar soil using tensiometer and without irrigation (I4) and sub plot factor was included seven soybean cultivars 033, 032, Sahar (belong to group maturity 4), L.17, Zan, Clark and Madari (belong to group maturity 3). To determine thermal requirement growth degree day system was used. Thermal units required by daily weather statistics for planting to flowering, planting to poding, planting to seeding, planting to maturity, seed filling period and reproductive period, were determined. At harvest time, the following data were recorded: Plant height, no. of seeds per plant, weight of seeds per plant, plant dry weight, seed and biological yields. Planting to poding period and planting to seeding period increased with reduction in water available and water deficit delayed appearance of pods. Water deficit decreased the yield components, significantly. Cultivar had significant effect on the yield components and all of phenological stages. The highest seed yield produced from 033 cultivar. In general, the results showed that water deficit is capable by delays in the occurrence of phenological stages in time and decreasing yield components, reduce yield of soybean. The lowest time for appearance of pods and the highest yield was belonged to I1. According to results, it seems that application of irrigation based on I1, can improve growth and yield of soybean in Rasht region.