Iranian Journal of Field Crops Research
Year:2004 | Volume:1 | Issue:1|Papers Count:11

To quantify the effects of moisture stress at different winter wheat (C-73-5) growth stages, a field experiment was set up at Mashhad in a complete random block design with seven treatments and three replications. The treatments were basin irrigation with water cut in a specified growth stages and a control treatment. Soil moisture was measured during the experiment by a neutron meter, and hence, crop actual evapo-transpiration was calculated by water balance method. Low rainfall amount did not disturb the treatments. The results showed that the treatments under water stress had a pronounced dry moisture profiles. Deep percolation was computed by subtracting moisture profiles at two consecutive time intervals. The computed sensitivity indices showed that flowering stage is the most sensitive stage, which is verified by other researchers. However, the derived values were not in harmony with these studies. Wheat variety, degree of stress, and other unknown reasons may support these differences. Leaf area index and crop height were more sensitive during flowering stage. Statistical analysis showed that the most influencing parameters on yield, leaf area index and crop height were due to water stress at flowering, tillering, and elongation stages, respectively. It observed, through comparison of means that the effect of stress on yield at flowering stage in mostly due to low spike rather than grain weight and number of grains per spike. We derived some models for predicting yield per unit of land also per unit of consumed water. However, the latter had lower correlation coefficients that the former.

In order to study the competitive effects of barnyard grass and redroot pigweed on dry bean yield, an additive experiment was conducted at Ferdowsi University of Mashhad experimental Farm station. The type of design was completely randomized block (CRBD). Treatments included three levels of redroot pigweed densities (4, 8, 12 plants/m2) and three levels of barnyard grass( 10, 20, 30 plants/m2), planted at constant density of bean(20 plants/m2) plus weed free check in each block. To interpret the competitive effects, the Cousense three parameters model were used. The results indicated severe damage of dry bean due to both weeds. Redroot pigweed resulted more reducing of dry bean compare to barnyard grass. The biological and economical yield reducing due to redroot pigweed was %74.05 and %76.48 and due to barnyard grass was %49.49 and %55.88 respectively. Also results from yield reduction model indicated high competitiveness of redroot pigweed. The comparison in biological yield of redroot pigweed and barnyard grass indicated that one redroot pigweed plant has competitive ability as much as fifteen barnyard grass in competitive with dry bean. Based on these results, these two weeds have the most effects on economical yield by reducing the number of lateral branches and reducing the number of pods per plant. 100 seed weight and the number of seed per pod did affect by none of these weeds.

Cotton is the most important fiber crop and its adaptation to different moisture conditions prepare the possibility of using less water for yield production. The objective of this experiment to study was the effects of delaying first irrigation (DFT) after emergence on cotton yield (lint and seed), lint quality as well as selection of the best sowing method. The experiment was conducted as a split plot arranged in a randomized complete block design with three replication in a silty loam soil at Kashmar Research Station in Khorasan province. Sowing method (planting before irrigation and sowing after irrigation) as the main plot and DFI based on accumulated pan evaporation (APE) in first year (70,140,210 and 280 mm APE) and in the second year (80, 160, 240, 320, 400 and 480 mm APE) as sub plots. Results showed that there were no significant difference between yield in two sowing methods, but there were significant difference in first (p<0.05) and second year (p<0.01) between DFI treatments. DFI up to 280 mm APE increased cotton seed yield, WUE, early maturity and number of reproductive branch but decreased vegetative branches in both sowing methods at first year. DFI up to 320 mm API increased seed cotton, HI, WUE. In the second year there were no significant differences in length, micron air, pressly and fiber quality in all treatments. High lint yield in low irrigated treatments might be due to increase in HI and boll number by effect water stress on lowering shoot / root. Results showed that in second year DFI after emergence until 320 mm APE increased seed cotton yield but lint quality remained unchanged in this year.

Root characteristics of wheat (Triticum aestivum L.) genotypes are widely believed to be important in tolerating water deficit. In order to investigate root growth and dry matter partitioning of five wheat cultivars differing in drought resistance, two separate experiments were conducted under well watered and moisture stress conditions using controlled environments at greenhouse, College of Agriculture, Ferdowsi University of Mashhad. A randomized complete block design with four replications and five wheat genotypes (Alavand, B.c. Roshan, C-73-5, Zarin and Navid) was used for each experiment. Genotypes did not differ in leaf number and leaf area under well watered conditions. Under water deficit conditions, resistant genotypes produced a greater number of leaves per plant and susceptible genotypes produced a lager leaf area per plant compared to other genotypes. Both shoot dry weight and root length for the drought resistant genotypes were significantly higher compared to the rest of others. Root dry weight and root/shoot ratio for the drought resistant genotypes were greater than the more sensitive genotypes, regardless of watering regime.

Photosynthetic response and stomatl conductance of two wheat and two barley ciiltivars under salinity stress In order to study the salinity effects on pholosyiilhelic response and stoiTiatnl conductance of two wheat (Ghods and CR) and barley cuUrvai-s (Cv.i. Val fajrand Chaal/al) I.\\u .separate grcenliotise experiments were condlictcd using spht plot design \villi (lirec replications. Three levels oT aiinity (0,100,300 mol 'h?I' by usins NaC177 aiid CaCli in 5: 1 molar ratio) were applied with Hoagland nutrient solution to sand growth medmi-n at three leaf growth stages. Photosynthesis, stomatal conductance, yield and yield components, reduulion of growth percentage, plani height nnd leaf number per plant were mea.sure(j. The rc?sulls indicated that photosynthesis rate andsLomatal conductance speciallv inihe sensitive cultivars (Ghods and ValfaJr). lhe dry matter production and seed yield were reduced due to salinity through reducI.ion of fertile tillers, spikelet niimbcrs in spike and seed weight, height of plant and number of leaves, C;hods and Valfajr eultivais were more sensitive to sahnity than CR and Chantzal. Delemiination of reduction of growth percentage indicated tliat salt resistant barley cuUiv'ars even in the highest salinity level (300 mol'm3).

To study the effect of salinity on growth, yield, elemental concentration and essential oil of cumin (Cuminum cyminum), an experiment was conducted at Ferdowsi University of Mashhad, College of Agriculture, during the years 2000 and 2001 growing season. Arandomized complete block design with three replications was applied. The experiment had five salinity treatments containing 0, 50, 100, 150 and 200 mollm3 by using NaCl-CaCl2 salts (10 to 1 molar ratio). Results showed that the salinity stress imposed a significant negative effects 6n cumin yield and yield components. Number of seed per umbel and final number of seeds per plant decreased at 50 mol/m3 salinity while did not show any effects on growth attributes including plant height, plant weight, number of umbel per plant and biomass yield. Salinity stress above this level to 200 mol/m3 has influenced all yield components including severe decrease on number of umbel per plant, number of seeds per plant and seed yield. With increasing levels of salinity seed and biomass yield were decreased significantly. Minimum seed yield was obtained at the highest salinity (200 mol/m3) level, but there was no significant difference between 200 and 150 mol/ m3. Results showed that salinity stress had no significant effect on percent of essential oil. Potassium concentration of leaves and root decreased while the sodium concentration of these organs increased with increasing salinity levels. The antagonistic effect between sodium and potassium caused these changes. Salinity increased hole stomatal resistance of cumin leaves but of 50 moll m3 had no significant influence on stomatal resistance. Relative water content of leaves was decreased with increasing salinity.

Although weeds affect the growth and yield of crops but no information is available about the situation of weeds in chickpea growing areas of Khorasan. This study was conducted to examine the effects of hand hoeing and plant population density (PPD) on weed dynamics of chickpea in irrigated (I) and rainfed (RF) conditions of these areas. Treatment comprised five weeding levels (non weeding, hand hoeing after 3,5 and 8 weeks after chickpea emergence and hand hoeing during whole growing season) and three PPD (20, 40 and 60 plant. m-2 in I and 20, 30 and 40 plant.m-2 in RF). The experiments were designed in a randomised complete block as a factorial experiment during 1996's growing season in two areas separately (I experiment in Mashhad and RF experiment in Sisab Bojnord). Population of Chenopodium album, Solanum nigrum, S. luteum and Amaranthus retroflexus in I conditions and Turgenia latifolia and Prosopis farcta in RF experiment were higher than other weeds. In both areas weeding 8 weeks after chickpea emergence caused the increases of weeds dry matter (WDM). In I and RF conditions PPD's 40 plant.m-2 and 30 plant.-2 had higher WDM than other treatments, respectively. The interaction between hand hoeing and PPD for WDM was statistically significant. In I experiment non weeding in 40 plant.m-2 and weeding during whole growing season in PPD 60 plant.m-2 and had the highest (236.1 gr.m-2) and lowest (8.5 gr.m-2 ) WDM, respectively. In RF conditions non-weeding in PPD 30 plant.m-2 had the highest WDM (28.25 gr.m-2) whereas in weeding during whole growing season in PPD 20 plant.m-2 WDM was 10% as compared with previous treatment (2.84 gr.m-2). As a whole, better weed control in I and RF conditions achieved in weeding 5 and 3 weeks after chickpea emergence.

In this study the effects of salinity on growth indices and cation accumulation of eight wheat cultivars (Ghods, Falat, Roshan, Cross Roshan , Cross Arvand, Mahdavi, Hearmand and Akberabady) were evaluated in Berjand at Amirabad experimental station. The experiment was conducted during 1999-2001 growing season, using three water sources of 1.4(control), 5.5 and 10.5 ds/m electrical conductivity. The experimental design was split plot in randomized complete block with four replications per treatment. Irrigation regimes were used as main plots, and cultivars used as sub plots. The results of growth analysis indicated that salinity stress caused reduction of dry mater, leaf area index (LAI), crop growth rate (CGR), and net assimilation rate (NAR). But, relative growth rate (RGR) was not affected significantly. Measurements of Na, K, and Na/K ratio showed that salinity enhances the concentration of these elements. However, Na and Na/K were higher than the K. Akbarabady and Roshan had higher growth parameters than other cultivars. These cultivars exhibited lowest amount of Na and Na/K. There is correlation between concentration of Na and Na/K ratio with salt tolerant in wheat our results indicated that Akbarabady and Roshan are salt tolerant cultivars, Falat is sensitive and the rest cultivars are semi salt tolerant.

The objective of this study was to investigate the effects of sowing date on yield and yield components of soybean cultivars with different growth habit in Golestan province. The experiment was conducted with a split- plot arrangement in a randomized complete block design with 4 replications. Main plots were sowing dates with five levels, (9 and 30A pr., 20 May, 10 June and 4 July.), and sub plot were cultivars with three levels (Williams, TI x SRF and PerxT1 determinate). Results showed that sowing date significantly affected pod per plant, seed weight, grain yield and plant height, but had no effect on seed per pod and node number in main stem. There was no difference between cultivars with respect to mentioned traits. Interaction effect (sowing date x cultivar) was significant only for grain yield. The highest grain yield was obtained at second sowing date (30 Apr.), and the lowest yields were measured at the last sowing date (4 July). In first three sowing dates, Per x T1 produced the highest grain yield, but in fourth sowing dates Williams and T1 x SRF yielded more. There was no evidence for advantage of any cultivar compared to others. However, it was concluded that the determinate cultivar is preferred for early, well- timed sowings.

In order to evaluate inoculation effects on soybean cultivars with different strains of Bradyrhizobium japonicum for determining the best bacteria-cultivar combination, an experiment as split plot design on basis of randomized complete block design was conducted in the field with 3 replications in spring and summer 2001. at Karaj Institute of Plant and Seed Breeding and Production. The factors were two cultivars of soybean (Williams and Line II) and four bacterial strains of japonicum including Helinitro, Highstick, Soyar and SWRI and a control plot (without bacteria). For prevention of infection between bacteria and convenience conduction, Bacteria spread in main plots and cultivars in subplot. Each experimental plot indaded 4 planted rows, elongation was 5 meters and distance between rows was 60 centimeters. Each replication consisted 5 main plots (each main plot had 2 subplots), therefore whole experiment had 30 plots. Characters such as grain yield and yield components including number of pod per plant, number of grain per pod, 1000-grain weight, oil and protein yields, fixed nitrogen work evaluated and N percentage in soil were measured by N-difference method. Although in this research no fertilizer was used but results of inoculated seeds compared to control plants and the results of the other scholars, showed that inoculation of soybean seeds had better characters than control, For example nitrogen fixation and grain yield in Line 11-Highstick combination was about thrice higher than Williams-no inoculated Treatment. The results showed that Highstick could fix more nitrogen than other strains. In the other hand, cultivar L11 had better symbiotic activity than cultivar Williams and fixed higher amount of nitrogen. Highstick and L 11, in most characters, showed to be the best combination in this experiment.

To examine the weeds loss and to determine the most suitable variable for wheat yield loss estimation in Field condition and multi species competition, of weeds An experiment was Carried out at the research field of agficultural Faculty of Ghaemshahr Azad University during 1998-1999. For the Purpose, 27 samples of 5x5(m) were selected from the field and in some stages, the weeds density species widow was counted, also at the end of the season dry weight oa all species were separately measured. To compare the competition and to evaluate and species loss coefficient, some variables such as, density, dry weight in are unit, crop equivalent ratio and average dry weight of weeds per plant were measured.According to the results, weeds biomass compared to the density had obtained better evaluation of wheat yield loss. In the following equation: considering the equation coefficient, it was observed that the weed interference effect on wheat can be divided in two groups; inhibition (positive sign) and stimulation (negative sign). The share of the wheat intraspecies competition was more than interspecies competition. Two species of Turnip weed (Rapistrum rugosum) and Wild oat (Avenafatua) had the most share in wheat yield loss, while Bird's eyes species (Veronica persica) and Wormwood (Artemisia sp.) showed the less effect on wheat yield loss in this experiment. It was found that the positive effect of some weeds, in relation to inhibition property themselves on the weeds that have the most capable competition.