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To investigate some common herbicides of transplanted rice for direct wet-seeding of Hashemi cultivar, this study was conducted in a randomized complete block design with three replications. Treatments were as follow: (i) recommended dose of pretilachlor, (ii) oxadiargyl + bensulfuron-methyl, (iii-vi) adding propanil or thiobencarb to treatment (i) and (ii), (vii-x) adding cinosulfuron to treatment (iii) to (vi), (xi) weed free condition, and (xii) weed infested condition. The highest total weed infestations were observed when pretilachlor, oxadiargyl + bensulfuron-methyl and pretilachlor plus propanil or thiobencarb had been applied. The highest rice height was recorded in weed infested, but for other traits, comparison of herbicide treatments showed the least rice growth and yield for pretilachlor (due to the highest weed competition) and oxadiargyl + bensulfuron-methyl + thiobencarb. In the recent treatment panicle and grain number, and 1000-grain weight were lower than those for individual application of pretilachlor. Since applying oxadiargyl + bensulfuron-methyl suppressed weeds better than treatments containing pretilachlor, and also considering the effective control of nutsedge by bensulfuron-methyl, and barnyardgrass by thiobencarb, it seems that the phytotoxicity effects of oxadiargyl + bensulfuron-methyl + thiobencarb on rice are serious. In the herbicide applied treatments, the maximum number of tiller and panicle, and biological and grain yield were observed in oxadiargyl + Bensulfuron-methyl+ Propanile treatments. Despite the acceptable weed control, it seems that Hashemi cultivar was susceptible to herbicides in saturated soil condition and symptoms of phytotoxicity were appeared in crop plants.

In order to investigate the effect of planting date and sowing method on ear yield, water use efficiency and some physiological characteristics of sweet corn, an experiment was carried out as a split plot based on a randomized complete block design with three replications in Yasouj, south-west of Iran. Planting date consisted of five levels (4 May, 19 May, 4 June, 19 June, 5 July) and considered as the main plots and three levels of planting methods (seed cultivation, transplanting cultivation [15-days after planting (3-leaf stage)] and [20-days after planting (4-leaf stage)] were assigned to the sub-plots. Planting date and sowing method interaction effects were significant on ear yield and water use efficiency. Transplanting at 3-leaf stage on the 4th of May had the maximum ear yield (16000 kg ha-1) and at 4-leaf stage on the 5th of July had the minimum ear yield (8000 kg ha-1). The highest water use efficiency (2.93 kg m-3) was obtained by transplanting on the 4th of May and 3-leaf stage, which was 66% higher than the water use efficiency of those transplanted on the 5th of July and at 4-leaf stage. The effects of planting date and sowing method were significant on grain protein content. With a delayed planting, the grain protein content was increased so that the maximum of grain protein content (8.7%) was obtained in the 5th of July and the lowest (8%) in the 4th of May transplanting. The grain protein concentration of the transplanting treatments was less than the grain protein of the seed cultivation treatment. The high temperature stress experienced by sowing at the 19th of May until the 19th of June decreased the grain sugar content. Transplanting cultivation led to increase in the amount of total sugar compared to seed cultivation. The best treatment in this study was found to be transplanting at 3-leaf stage on the 4th of May.

In order to determine the optimal rates of Pertilachlor and Sunrice­-plus herbicides for weed control of rice (Oryza sativa Var.Tarom Hashemi), a factorial experiment was conducted with a randomized complete block design with four replications in Rice Research Farm of Faculty of Agriculture, University of Guilan, Rasht, northern Iran. The first factor was weed control treatment which consisted of lower than, equal, and more than recommended levels of Pertilachlor (i.e. 0.5, 0.75, 1 kg a.i ha-1) and Sun­rice plus (0.45, 0.9, 1.35 kg a.i ha-1) herbicides, along with unweeded and twice hand-weeded controls. The second factor consisted of two levels of nitrogen fertilizer (N) application (i.e. 0 and 90 kg ha-1 of N). Barnyardgrass (Echinochloa crus-galli L.) and Purple nutsedge (Cyperus rotandus L.) were the most dominant weeds of the experimental plots. The highest number of filled panicles per plant, number of grains per panicle, and grain yield were found in recommended rate of Pertilachlor, Sun­rice plus and more than recommended rate of Sun­rice plus due to adequate weed control (>70%) at the presence of 90 kg ha-1 of N. The lowest number of grains per panicle, number of panicles per plant and grain yield were observed in unweeded treatment, at both levels of nitrogen fertilizer application. It was concluded that application of N is effective in increasing grain yield of the examined rice genotype only if weeds are effectively controlled by herbicides. Hence, application of N in the unweeded conditions does not lead to an increase in grain yield of rice, because the consumption of N by weeds decreased the effect of nitrogen on rice grain production.

In order to evaluate the benefits of maize, pinto bean and naked pumpkin triple cropping, an experiment was carried out as a randomized complete block design with three replications at Faculty of Agricultural Science, University of Guilan, Rasht, Iran in 2012. The treatments consisted of maize, pinto bean and naked pumpkin sole cropping (100, 75 and 50% of conventional densities), maize – pinto bean and maize – pumpkin double cropping (100-100%, 75-75% and 50-50%), and maize-pinto bean-pumpkin triple cropping (100-100-100%, 75-75-75% and 50-50-50%). The highest and lowest forage fresh weights were obtained in triple cropping system with high density and sole cropping systems with low density, respectively. In double cropping systems, the maize-pumpkin out-yielded the maize-pinto bean in terms of fresh weight. The relative crowding coefficient, competitive ratio and aggressivity of maize in double cropping of maize-pinto bean and naked pumpkin in double cropping of maize-naked pumpkin were dominant. In triple cropping systems, while maize and naked pumpkin were comparable, but both of the latter crops were dominant over pinto bean. Land Equivalent Ratio (LER) for double and triple cropping was greater than one, revealing the profitability of double and triple cropping systems on sole cropping. According to the LER, the cropping systems can be ranked as follows: triple cropping > double cropping maize/pinto bean > double cropping maize/pumpkin

Abutilon theophrasti and Barnyardgrass (Echinochloa crus-galli) are major weeds that affect cropping systems worldwide. Laboratory and greenhouse studies were conducted to determine the effects of temperature, pH, water and salinity stress, and planting depth on seed germination and seedling emergence of Velvetleaf and Barnyardgrass. For Velvetleaf, the base, optimum and ceiling germination temperatures were estimated as 5, 35 and 48 ºC, respectively. Seed germination was sensitive to drought stress and completely inhibited by a potential of -0.6 MPa, but it was tolerant to salinity. Salinity stress up to 45 mM had no effect on the germination of Velvetleaf, but germination decreased with increasing salt concentration. Drought and salinity levels for 50% inhibition of maximum germination were -0.3 MPa and 110 mM, respectively. Seed germination of Velvetleaf was tolerant to a wide range of pH levels. For Barnyardgrass, the base, optimum and ceiling germination temperatures were estimated as 5, 38 and 45 ºC, respectively. Seed germination was tolerant to drought stress and completely inhibited by a potential of -1.0 MPa. Salinity stress up to 250 mM had no effect on seed germination. Drought and salinity levels for 50% inhibition of maximum germination were -0.5 MPa and 307 mM, respectively. A high percentage of seed germination was observed at pH=5 and decreased to 61.5% at acidic medium (pH 4) and to 11% at alkaline medium (pH 9). Maximum seedling emergence of Velvetleaf and Barnyardgrass occurred when the seeds were placed on the surface of the soil or at a depth of 1 cm.Abutilon theophrastie Echinochloa crus-galli são as principais plantas daninhas que afetam os sistemas de cultivo em muitas partes do mundo. Estudos em laboratório e em casa de vegetação foram conduzidos para determinar os efeitos da temperatura, pH da água e estresse salino e da profundidade de semeadura na germinação e na emergência das plântulas de A. theophrasti e E. crus-galli. Para A. theophrasti, as temperaturas de base, ótima e de teto de germinação foram estimadas em 5, 35 e 48ºC, respectivamente. A germinação das sementes foi sensível ao estresse hídrico e inibida completamente por um potencial de -0,6 MPa, mas foi tolerante à salinidade. Estresse salino de até 45 mM não teve nenhum efeito sobre a germinação de A. theophrasti, porém esta diminuiu com o aumento da concentração salina. Os níveis de seca e de salinidade para 50% de inibição da germinação máxima foram de -0,3 MPa e 110 mM, respectivamente. A germinação das sementes de A. theophrasti foi tolerante a uma vasta gama de níveis de pH. Para E. crus-galli, as temperaturas de base, ótima e de teto de germinação foram estimadas em 5, 38 e 45ºC, respectivamente. A germinação das sementes foi tolerante ao estresse hídrico e inibida completamente a um potencial de -1,0 MPa. Estresse salino de até 250 mM não teve efeito sobre a germinação das sementes. Os níveis de seca e de salinidade para 50% de inibição da germinação máxima foram de -0,5 MPa e 307 mM, respectivamente. Elevada porcentagem de germinação das sementes foi observada a pH=5, com diminuição para 61% em meio ácido (pH=4) e para 11% em meio alcalino (pH=9). A máxima emergência das plântulas de A. theophrasti e E. crus-galli ocorreu quando as sementes foram colocadas sobre a superfície do solo ou a uma profundidade de 1 cm.