F. Momtazi, Y. Emam, N. A. Karimian,
Volume 9, Issue 3 (fall 2005)
Abstract
The physiological characteristics of winter wheat(cv. Shiraz) were evaluated in a 2-yrs field study by using a spilit plot design with four replications, at the experimental farm of Shiraz University, College of Agriculture located at Badjgah. Main plots consisted of three sowing dates (November 6th, December 6th and January 5th) and four planting densities (150, 250, 350 and 450 plants/m2) were assigned as sub plots. The results indicated that delay in sowing was associated with a significant reduction in the grain yield. So that the grain yield in sowing date of January 5th was significantly less than it in sowing dates of November 6th and December 6th. Moreover with delay in sowing date the developmental rate of wheat was enhanced and plants reached maturity more rapidly. The trend of the leaf area index changes and the dry weight of the plants were under the effect of experimental treatments, leaf area index was found to be greater at the higher densities and early planting date. Number of stems per m2 were decreased with delay in the sowing date, although at the higher densities, the number of stems per m2 was greater, despite severe tiller death observed at these densities. The study of trend of dry weight changes during the season indicated that biomass was greater at higher densities and earlier sowings, which resulted in earlier ground cover and higher amount of radiation interception. In conclusion, the results of the present investigation revealed that to achieve a reasonable grain yield, the 6th of December and 250 plants per m2 were the best sowing date and planting density for wheat (cv. Shiraz) under similar agro climatic conditions with the present investigation.
J. Bayazzadeh, E. Sepehr, H. Momtaz,
Volume 23, Issue 2 (Summer 2019)
Abstract
To study the behaviour of phosphorus (P) sorption in the agricultural soils of Khoy region and the effect of long-term cultural management with the application of poultry manure on the P sorption parameters, bath experiments were carried out with 16 soil samples (8 cultivated and 8 virgin soils) and 9 initial P concentrations from 0 to 30 mg L-1 in 0.01M CaCl2 as a background solution. After equilibrium, the remaining amount of P in solution was measured and the experimental sorption data were fitted to the Langmuir (R2=0.93-0.99) and Freundlich (R2=0.87-0.99) models. The results showed that P sorption was increased with enhancing the initial P concentration, eventually reaching the steady-state plateau. Based on the coefficient of determination (R2) and the standard error of estimate (SE), both isotherms models, Langmuir and Freundlich, showed a relatively good fit to the experimental data. The maximum mono layer sorption of Langmuir (qmax) varied from 233 to 486 and from 340 to540 mg kg-1, and the energy parameter of Langmuir (KL) ranged from 0.12 to 0.50 and from 0.22 to 0.71 for the cultivated and virgin soils, respectively. Freundlich sorption capacity (KF) and intensity (n) parameters showed the same trends and KF varied from 36.4 to 123 and 59.3 to 145.2; also n varied from 1.18 to 1.50 and 1.47 to 1.71 in the cultivated and virgin soils, respectively. Consequently, all sorption parameters and the buffering indices showed a decreasing trend in the cultivated soils, as compared to the corresponding virgin soils and the cultural and fertilization management; especially, the application of the poultry manure in this region reduced phosphorus sorption by soil and then increased phosphorus availability to plants. Hence, less fertilizer would be needed to maintain a favourable P concentration in the soil solution for the optimum plant growth.
