Iranian Journal of Crop Sciences
Year:2001 | Volume:3 | Issue:1|Papers Count:8

In order to investigate effects of different planting spaces on morphological and physiological characteristics and also on quantitative yield of sugar beet, an experiment was conducted in Safi-abad Research Center of Dezful during 1998-2000. This study was carried out in strip plot design. Treatments contained 20 stand density in intersection plot composing of four row spacing (45, 55, 65 and 75 cm) and five inter row spacing (15, 20, 25, 30, and 35 cm). The results showed that spacing had significant effect on number of green and dead leaves. Interaction for green leaves in two years and dead leaves in 1999-2000 was not significant while interaction effects for dead leaves was only significant in 1998-99. The number of green and dead leaves per plant negatively correlated with stand density. But those factors were positively correlated with increase in planting spaces. Mean number of maximum green and dead leaves in two years ranged from 38.4 and 40, respectively per plant with 38000 plant/ha (75x35) to 23.9 and 15.4 per plant with 148000 plant/ha (45x15). Stand densitywas positively correlated with leaf area index (LAI). Mean of maximum LAI differed from 6.4 in 148000 plant/ha to 3.3 in 38000 plant/ha.

In order to investigate the effects of plant density and nitrogen rates on physiological indices and yield of corn (var. SC704), a field experiment was conducted as split-plot arranged in a randomized complete block design with four replication in 1999 at Koushkak Agricultural Research Center of Shiraz University The treatments composed of nitrogen at four rates: 0, 80, 160 and 240 kgN/ha as main plots and plant density at four levels: 6, 7.4, 8.8, and to.2 plants/m2 as sub plots. Physiological indices was affected by N rates. Increasing N from 0 to 80 kg/ha considerably increased leaf area index. Increasing N from 0 to 80, and 160 kg/ha increased crop growth rate and leaf area index duration. Increasing N from 160 to 240 kgN/ha decreased crop growth rate. Among physiological indices, net assimilation rate was less affected by N application. Net assimilation rate declined during growth season. Increasing plant density, increased leaf area index, leaf area index duration and crop growth rate, but decreased net assimilation rate. Increasing leaf area index at field increased light interception and therfore increased photosynthesis capacity of plant that finally caused increased grain yield. The major increase in CGR under high plant density was due to increase of LAI. Considering the importance of LAI, CGR and LAID on grain yield it was concluded that the major increase in grain yield under high plant density was due to improvement of physiological indices.

An experiment was conducted to determine the correct way of chemical control to the dodder in sugar beet in Miandoab Agricultural Research Station in 1998. A factorial experiment in completely randomized block design with four replications was used, in which, factor (A) was the type of the herbicide in three levels containing: Trifluralin a1, Propyzamid a2 Ethofomisate a3; factor (B) was the dosage of the herbicide in three levels containing: 0.8 kg ai ha-1 b1 1.2 kg ai ha-1 b2, 1.6 kg ai ha-1 b3 with two positive & negative checks. Results indicated that dodder weed decreased root yield and the percent of sugar by 30% and 2.13% respectively as compared with uncontaminated check. The herbicide of Trifluralin decreased numbers of grown bushes, yield rate and percent of sugar at most in order of : 53%, 35% and 2.9% respectively as compared with uncontaminated check and also decreased contamination of dodder just 23% and it hadn’t any phytotoxicity effects in rotation with wheat. Propyzamid decreased the parasitical plant of dodder at most to 87% as compared with complete contaminated check and increased the yield in three levels in order of: 29%, 30.71% and 35.22% as compared with complete contaminated check and also increased the percent of sugar as compared with complete contaminated check in the three levels in order of: 1.17%, 1.44% and 1.52% and it did not show any phytotoxicity effects on wheat rotation. Ethofomisate decreased just 19% of dodder contamination and also increased root yield of sugar beet in three levels of: 24.5%, 29.3% and 28.31% as compared with uncontaminated check and increased the percent of sugar in three levels in order of: 1.05%, 1.69% and 2.44% as compared with uncontaminated check. Ethofomisate also did not show phytotoxicity effects on wheat rotation.

Precise understanding of physiological processes controlling the yield lead to increased crop yield potential. In order to evaluate the effects of different plant densities; growth; fresh and dry weight of sorghum hybrids and a sudangass cultivar, an experiment was conducted in a factorial design in completely randomized block with four replications in research farm of Torbat-jam at Islamic Azad University during 1998-99. Treatments were plant densities (25, 35 and 45 plant m-2) and two sorghum hybrids (Jambo, Speedfeed), a sorghum landrace, and a sudangrass cultivar. Results showed that plant densities had no significant effect on fresh and dry weight. However Duncan’s multiple range test showed that 35 plants per m2 had higher yields and produced 80.94 and 37.63 ton ha-1 fresh and dry weight, respectively. Speed feed had better morphological and physiological characteristics and produced the highest fresh and dry yield by 93.4 and 43.38 ton ha-1 respectively. However, speedfeed was ranged with Jambo in one group. Total dry matter increased after 210 days after planting in all cultivars and then decreased which curve slope in landraces, sudangrass was lower than other cultivears. The highest relative growth rate (RGR) was observed 130 days after planting and was reducing during growth season. Speedfeed showd higher RGR than other cultivars in all growth stages but final stage

In order to evaluate the response of six dryland wheat genotypes under supplemental irrigation conditions, an expriment was carried out during 1998-99 cropping season (year) at Ghamloo Research Station in Kurdistan Province. A split plot design experiment using randomized complete block in which five irrigation treatments as main plots and six dryland wheat genotypes as subplots with four replications was used. Results showed that a significant positive correlation between grain yield and number of ears per square meter was. found (r=0.526**). Among wheat genotypes Sabalan cultivar over all irrigation treatments produced an average yield of 2213 kg ha-1 which was the highest and Sardari produced an average yield of 1502 kg ha which was the lowest. The highest protein concentration belonged to Sxl/Gelenson under check treatment (15.81%) and the lowest belonged to Kvz/Tm 71/3/Moya "S"/Bb wheat genotype (12.23%) under supplemental irrigation at planting plus milking stages. In general; supplemental irrigation at milking stage increased 54 percent of grain yield in Sabalan (compared to check) and produced the highest yield.

In order to study the symbiosis relationships of Azosporillum bacteria, Mycorrhiza fungi, and Streptomyces from actinomycetes with the roots of wheat as biofertilizers that could provide plant nutrients and its protection, a research was conducted under greenhouse condition. Manure (dung) was used as biofortilizer. Interactions of the three mentioned microorganisms were studied using 32p. Factorial experiment in completely randomized design with three replications was used in which two levels of each microorganisms and manure (one with and one without using) were applied. Results showed that using Azospirillum, Mycrorhiza, and manure, individually, caused significant increase in plant height, tiller per plant, plant dry weight, and activity per plant. Also, manure increased stem diameter significantly. Results of threefold and fourfold interactions of experimental factors showed that utilization of Azospirilum and Mycorrhiza specially with manure increased most of the characters. A negative antagonistic interactions between Mycorrhiza and Streptomyces was found. However, there was not any antagonistic interactions between Azospirillum and Streptomyces.