نشریه پژوهشهای زراعی ایران
سال دوم شماره 2 (پیاپی 4، پاییز و زمستان 1383)

Weed scouting is an important part of integrated weed management system. In order to evaluate weed emergence pattern and management efficiency on weed populations, a 2 ha sugarbeet field in Mashhad was selected and evaluated during 2002 growing season. Weeds were identified and counted at 441 points at the intersection of a 7m by 7m grid within 0.15 m2 quadrates. The evaluations were done 3 times [pre management (1) and post management (2)]. Geostatistical techniques (kriging) were used to analyze the spatial structure of weeds and dynamics of weed patches. 34 weed species were observed across the field. Wide ranges of weeds were observed during growing season including, winter annual (e. g. Sinapis arvensis and Fumaria officinalis), summer annual (e. g. Echinochloa crus-galli), biennial (Dacus caraota) and perennal (e. g. Convolvulus arvensis). Solanum nigrum, Chenopodium album, Amaranthus spp., Convolvulus arvensis, Polygonum aviculare and Echinochloa crus-galli were the common weeds over growing season. In early growing season, Solanum nigrum with 404.71 seedlings per m2 was present in all samples constituted 81.32% of weed community, but in 2nd and 3rd sampling time, Convolvulus arvensis was the dominant species with 33.29% and 29.26% of weed community. Relative density percentage of perennial and grassy weeds (generally C4 species) was increased over the season but the relative density percentage of broadleaf annual weeds was decreased. Main locations of weed emergence were persisted as elliptical patches east ward and west ward of field over the season. The results of this study indicated that scouting and understanding of weed emergence behavior could be used to design effective strategies of weed management.

In order to evaluate agricultural knowledge of cumin growers in Sabzevar, a survey was conducted for 150 cumin growers. Dependent variables were allocated to the level of their knowledge in three phases of planting, crop management, harvesting‌, and the extent they benefit from extension services‌, age, level of education, farming experiences and size of family were the independent variables‌. Results showed that only 18 % of the farmers were knowledgable In farming practices and methods of irrigation and fertilizer application contributed the highest rank‌, while processing and packing the products shared the lowest rank. There was a positive correlation between the level of education and all dependent variables (‌at 5% level‌)‌. There was no correlation between the size of family and the level of knowledge, and young farmers were more knowledgable in farming practices compared with the olders. Role of extension services in promoting these knowledge particularly in planting‌, and diseases control was significant‌. However such role was not effective in harvesting and processing.

A laboratory study was conducted to investigate the effect of different temperatures on seed germination of two species of Plantago namely P. ovata and P. psyllium in a completely randomized design with four replications. Various constant temperature (5, 7, 10, 15, 20, 25, 30 and 35 ◦C) were considered. According to the results, the effect of temperature on rate and percentage of seed germination in both species was significant. The highest germination rates were in 20 and 25 ◦C for P. ovata and P. psyllium, respectively. Maximum seed germination occurred for P. ovata (100%) and P. psyllium (99%) in 15 and 25 ◦C, respectively. Optimum thermal range for seed germination of P. ovata was (10-20◦C) and for P. psyllium was (15-25◦C). By increasing or decreasing temperature beyond the optimal thermal range, percentage of seed germination was decreased significantly. Based on linear regression between germination rate and temperature in both species, the cardinal temperatures: minimum(Tmin), optimum(To) and maximum (Tmax) were determined which were: 4.4, 19.0 and 25.5 ◦C for P.ovata and 9.4, 28.8 and 35.0◦C for P. psyllium, respectively.

In order to examine seed germination responses of kochia to different levels of salinity, an experiment was performed in the Institute of Sustainable Agriculture (CSIC), Cordoba, Spain, in a completely randomized design with two replications. Treatments were different levels of salinities equal to 0,5, 10, 15, and 20 ds/m, obtained by mixing NaCl and CaCl2 in a 2:1 molar ratio. Evaluated properties were germination percentage, rate and final number of germinated seeds. The results showed that the germinated seed number and the germination percentage had a converse relation with salinity levels. About 91% of seeds were germinated in distilled water. This value reduced to about 36% in 20 ds/m. Increasing salinity up to 10 ds/m did not have any significant effects on germination, but after that, the germination rate and percentage begun to reduce significantly. Salinity also increased the time required for 50% germination from 28 hours in distilled water to 78 hours in 20 ds/m, showing a delay in germination as salinity increased. Regarding linear reduction in germination rate in response to increase in salinity, it seems that as salinity exceeds 30 ds/m, germination rate of kochia approaches zero. This perhaps could be accepted as the threshold of kochia germination tolerance to salinity. According to the results, the germination stage of kochia has a good tolerance to elevated levels of salinity and it seems that a good stand establishment in saline soils and water conditions could be insured, if proper management is exerted in farms.

An experiment was conducted during 1996-1997 growing season in Mashhad, NE of Iran to evaluate the genetic improvement in ecophysiological traits that enhance the competitiveness of Iranian winter wheat (Triticum aestivuml) against wild oat (Avena ludovicianal). Six Iranian winter wheat cultivars which have been released during the past 40 years were used for this experiment. A factorial experiment was arranged in a randomized complete block design with three replications. Each cultivar was planted at its own optimum seeding rate with and without competition with wild oat. Wild oat was planted at a constant density of 80 plants per square meter. The results showed that more recent cultivars had much higher competitive ability compared to earlier cultivars. Alvand (the most recent cultivar) had higher dry matter accumulation, crop growth rate (CGR), leaf area index (LAI) and relative leaf area growth rate (RLGR) compared to Bezostaya. Alvand had a higher proportion of its leaf area in higher canopy layer. Wild oat was also shorter in height when it was competing with Alvand compared to Bezostaya. It was found that following characteristics were the most important criteria in competitive ability of winter wheat against wild oats: 1) leaf area at the end of tillering stage. 2) final leaf area index. 3) relative leaf area index, and 4) the canopy layer where the higher leaf area was measured

The response of two varieties of Canada thistle (Horridum, and Integrifolium) to 14 herbicides was examined under controlled environment conditions in 2000, at Saskatoon, Saskatchewan. Each herbicide constituted a separate experiment. Each experiment was arranged in a completely randomized design with four replications (one pot per replicate). Each herbicide was applied at 0, 0.125, 0.25, 0.5, 1, and 2 times the recommended rate (in g a.i. ha-1): metsulfuron, 4.44; 2,4-D, 876; 2,4-DB, 1400; clopyralid, 152; dicamba, 128; MCPA, 876; MCPB, 1700; MCPB+MCPA (15:1, respectively, by volume), 1700; mecoprop, 926; hexazinone, 1008; bentazon, 840; bromoxynil, 336; glyphosate, 880; glufosinate, 500. Twenty-one days after treatment, shoots were cut at soil level, and dry matter was determined. For statistical analysis of the dose-response data were fitted to a log-logistic model. Shoot dry matter responses of the Canada thistle varieties to the herbicides were described well by log-logistsic model. Results indicated that bromoxynil, and hexazinone had maximum effect, and metsulfuron minimum effect on Canada thistle (based on control effect index). Varieties horridum and integrifolium responsed differently to increasing rates of hexazinone only. Variety integrifolium was 40% less sensitive to the herbicide than variety horridum. If can not attribute the lack of control to soil properties or environment, it should ascertain the varietal type.

In order to determine the critical period of weed control in corn, an experiment was conducted at Research Station, Faculty of Agriculture, Ferdowsi University of Mashhad in year 2000. The experiment consisted of two discrete periods, a weed-free and a weed infested period. The weed-free period consisted of removing all weeds till 4th (19 days after planting), 7th (34 days after planting), 11th (48 days after planting), 13th (52 days after planting), and 17th (59 days after planting), leaf growth stages and weed free check for growing season (123 days after planting), and the critical time of weed infested consisted of removing all weeds from fourth (19 days after planting), 7th (34 days after planting), 11th (48 days after planting), 13th (52 days after planting), and 17th (59 days after planting), leaf growth stages and weedy infested check for growing season. All treatments were compared in a randomized complete block design with four replications. The results showed that by prolonging weed-infested period, dry matter and leaf surface area of weeds per square meter were increased, but by increasing weed-infested period, weed density was decreased. The lowest weed density (23 weed plants per m2) was shown at infested all period of corn growing season. By passing the growing season, C4 weed species such as red root pigweed and barnyard grass were dominant compared with C3 weed species. At weed infested all period of corn growing season, red root pigweed had the highest dry matter (93% of all weeds dry matter) and leaf surface area (86% of all weeds leaf surface) compared with other weed species. At the first treatment of critical weed-free (19 days after planting) the regrowth of weeds were substantial which resulted in decreasing growth of corn. Grain yield of corn were significantly higher at 52, 59 and 123 days after planting in weed free treatments compared with 48, 52, 59 and 123 days after planting in weed infested treatments. However, there were no significant differences between other treatments. Based on the fitted sigmoid equation for both treatments at 10% decreasing grain yield compared with control, the critical period of weed control in corn was obtained between 20 till 56 days after planting (fourth till fourteen leaf stage) at Mashhad climatic conditions.

A factorial arrangement of three millets species (Panicum miliaceum, Pennisetum glaucum, and Setaria italica) and two sowing dates with three replications were used in a completely randomized design to evaluate the radiation use efficiency and its relationship with dry matter accumulation. Leaf area index was used in daily intervals to calculate daily intercepted radiation. Light extinction coefficient was calculated as the slope of regression line between log transformed fraction of intercepted radiation and leaf area index during growing season. Radiation use efficiency was calculated as the slope of linear regression between cumulative intercepted radiation and cumulative biomass during growing season. Results showed that light extinction coefficient and radiation use efficiency for proso, pearl and foxtail millets were 0.75, 0.66, 0.57 and 1.43, 1.83, 1.74 g/MJ in terms of total radiation, respectively. Differences in biomass production were not significant between proso and pearl millets. Proso millet had higher intercepted radiation, but lower radiation use efficiency in comparison with pearl millet. Foxtail millet had lower intercepted radiation than proso and pearl millets, but its radiation use efficiency was higher than pearl millet. Total biomass of foxtail millet was lower than other species. Results indicated that proso and pearl millets can produce more biomass than foxtail millet.

The stable production and sustainability of agroecosystems are highly threatened by modern farming systems which focus on uniformity and narrow diversity of species. Wild harvested and semi domesticated plant species play an enormous role in biodiversity of traditional agricultural systems, and many of them with medicinal and traditional agricultural systems, and many of them with medicinal and industrial properties are introduced as new crops to global markets. The results showed that nearly 55 species with medicinal and aromatic properties are cultivated in Iran. The Shannon index for these species was 0.64. Their cultivated land areas include 0.‌87 % of the total arable lands of the country. Khorasan province has the highest cultivated land areas and agrobiodiversity of medicinal and aromatic plant species in Iran.

Students awareness from the principles of sustainable agriculture were evaluated among undergraduate and graduate students with specialization in agronomy, horticulture, phytopathology, soil sciences and irrigation in 8 universities around the country including Tehran, Tabriz, Shiraz, Hamedan, Kerman, Mashhad, Azad Eslami–Mashhad and Science and Research Center of Azad Eslami–Tehran. Evaluation was conducted using questionnaires containing 12 questions about concepts (8 question) and application (4 questions) of sustainable agriculture. Two additional questions were included for assessing students’ views about their main source of information and the importance of inclusion of formal courses on sustainable agriculture in the current curriculum. Results of 347 questionnaires were extracted and exposed to analysis of variance and proper statistical comparisons. Frequency of correct answers was significantly different between universities. While students’ knowledge about concepts of sustainable agriculture was significantly lower than its application, frequency of corrects answers were never exceeded 50%. Students with specialization in agronomy and horticulture had significantly higher awareness from both concepts and application of sustainable agriculture compared to other specializations. Educational level was also an important source of variation in students’ knowledge. However, the observed difference between specializations was the same for graduate and undergraduate students. Informal books and scattered information within formal courses were the main sources of students’ information on principles of sustainable agriculture. Importance of inclusion of special courses on sustainable agriculture in the current curriculum was rated as high to very high by 70 and 93% of undergraduate and graduate students, respectively.

In order to investigate the effects of different drought levels and planting dates on yield and yield components of chickpea, an expriment was conducted during 2003 growing season in Mashhad. Two planting dates including 9 January and 18 February, four drought levels including I1=no irrigation, I2= irrigation only at planting time, I3= irrigation at planting time and before flowering I4=irrigation at planting time, before flowering and podding and three Kabuli chickpea cultivars (Jam, Karaj 12-60-31 and ILC 482) were compared in a factorial experiment based on randomized complete block design with three replications. Drought levels and planting dates affected pod and grain numbers per square meter as well as 100 grain weight significantly. Three - time irrigation (I4) had maximum grain yield. Karaj 12-60-31 cultivar had the highest grain yield and ILC 482 cultivar had the lowest. Jam cultivar was the most tolerate to water stress conditions but Karaj 12-60-31 with three - time irrigation had the most grain yield.

An experiment was carried out to evaluate the effects of planting depth and rhizome sizes on below ground growth of licorice (Glycyrrhiza glabra L.) at research glasshouse of Mashhad Unversity in 2001. Factorial experiment containing 2 factors of planting depth (10, 20 and 40‌cm) and rhizome sizes (1,2 and 3 buds or 4,7 and 10 gr) with two replications in completely randomized block design was employed. Development of different variables during growing season including root and mother rhizome dry weight were measured.The highest and the lowest root dry weight (RDW)have been seen in depth of 20 and 40 cm‌, respectively. About 100 days after planting (DAP), RDW increaseed very slowly but thenafter increased faster‌. Rhizome of any sizes in‌ 20 cm, gave the highest RDW‌. Three-bud rhizomes produced the highest RDW and 1-bud rhizome produced the lowest. Mother rhizome dry weight (MRDW) reduced untill 60 days after planting. After 75th day, MRDW has increased and all plants started to fill their mother rhizome and finally rhizome of depth 20 cm produced the highest dry weight. In 160 days after planting, mother rhizomes started to lose their weight‌. 1and 3 -bud mother rhizome produce the lowest and highest MRDW, respectively.