To evaluate the effect of nitrogen and water withholding in vegetative growth stage of corn on efficacy of nicosulfuron and 2,4-D+ MCPA an experiment was conducted as a factorial arrangement in a randomized complete block design with three replications at Tarbiat Modares University in 2017. The first factor contained four treatments including application of nicosulfuron, 2,4-D+ MCPA, weed free and weed infested as control. The second factor consisted of normal irrigation and water withholding from 4 to 8 leaf stage. Third factor contained either urea application or no fertilizer application. Normal irrigation and nitrogen fertilizer application significantly increased nicosulfuron and 2,4-D+ MCPA efficacy in weed control and total weed dry weight decreased to 341 and 361 g.m-2 respectively compared 1370 g.m-2 as weed infested. Nicosulfuron and 2,4-D+ MCPA reduced weed total dry weight significantly under irrigation withholding. Grain yield increased with application of nitrogen and nicosulfuron. Grain yield was higher with application of 2,4-D+ MCPA than nicosulfuron without nitrogen application under irrigation withholding. Application of nicosulfuron with nitrogen application provided satisfactory weed control and increased grain yield.

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.

The control of different agricultural insect pests still relies mainly on the use of synthetic insecticides. However, excessive use of these chemicals cause many problems, including high residue levels, harmful effects on the environment and human health, and development of insect resistance. Therefore, new strategies for the MANAGEMENT of agricultural insects are urgently needed. Plant-based natural products are promising alternatives to be applied for pest control, with remarkable and broad-spectrum biological activities. Among the plant secondary metabolites, essential oils, and their major constituents, mainly monoterpenes, have been widely studied for their application in insect control, food additives, perfumes and cosmetics. In this review, we focus on the studies describing the toxic effects of monoterpenes, including fumigant, contact and residual toxicities against insect pests attacking economic CROPs in fields. Furthermore, the effects of monoterpenes on insect behaviors (antifeedant and repellent activities) and insect growth regulation are also discussed.

This study was aimed at evaluating the effect of CROP rotation and various tillage systems on the chemical and biological properties of soil in the years 2013-2015. The first order factor included CROPping systems: a) CROP rotation (pea-winter wheat-spring wheat) and b) monoculture of winter wheat, whereas the second order factor were tillage systems: 1) conventional (CT), 2) reduced (RT) and 3) No-tillage (NT). In the autumn season, in the CT system, shallow ploughing (at the depth of 10-12 cm) and pre-winter ploughing (25-30 cm) were applied for pea and spring wheat CROPs, whereas shallow ploughing and pre-sow ploughing (20-22 cm) were applied for winter wheat CROP, in the RT system, only a cultivator was applied for spring wheat and pea CROPs as well as a cultivator and a tillage set for winter wheat, in the NT system glyphosate was applied on all plots as well as a cultivator and a tillage set were used before winter wheat sowing. The study demonstrated that the soil sampled from plots with CROP rotation contained more organic C and available forms of P, K and Mg and that it was characterized by a higher activity of dehydrogenase, phosphatase and urease than the soil sampled from monoculture. In addition, it was characterized by a higher number of earthworms than the soil from monoculture. The RT and NT systems affected an increase in the contents of organic C and total N and in the enzymatic activity of soil, compared to the CT system.

The model WOFOST, which simulates the growth and development of annual field CROPs under conditions of potential production, water and nutrient limitations. The model was evaluated against a data set of field experiments. The study was laid out in RCBD with 3 replications for one popular traditional landrace Hashemi carried out in 2005 at Rice Research Institute of Iran, Rasht. The irrigation MANAGEMENT were I1 with continuous irrigation while I2, I3, and I4 were irrigation 1, 3 and 5 days after water disappearance of pounded water and I5, I6 were irrigation at 5 and 8 days intervals. We compared simulated and measured leaf area index (LAI) and biomass panicles and total aboveground biomass by adjusted coefficient of correlation (R2), T test of means, absolute and normalized root mean square errors (RMSE) and modeling Efficiency (EF). On average, RMSE of model were 389-553, kg ha-1 for total biomass, 139-246 kg ha-1 for panicle biomass and 0.46-0.58 cm2cm-2 for LAI. For these CROP variables, normalized RMSE values were 10-14 for total biomass, 7-16 for panicle biomass, and 54-83 for LAI. The WOFOST model Simulated LAI generally exceeded measured values.