JWSS - Journal of Water and Soil Science

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Quantity-intensity (Q/I) curves and their derived parameters provide general information about soil K availability. This investigation was conducted to obtain Q/I parameters and to study the relationships between the Potassium Q/I parameters and the properties of 15 soils from central and northern Iran. Soil samples were equilibrated with solutions containing different potassium activity ratios (AR^k). Changes in potassium concentrations in the equilibrium solution (ΔK) were plotted against activity ratio of K, and Q/I parameters were determined. Correlations between Q/I Parameters and some properties of soils were studied.

The Q/I plots showed the common shapes described in the literature whereas high variations were observed in the soils with respect to AR°, ΔR°, BPC^k and K_x. The potassium activity ratio at equilibrium ranged from 0.005 to 0.532 with an average of 0.02 (mmol L^-1)^0.5. The potassium potential buffering capacity (PBCk) ranged from 4.40 to 76.3 with an average of 16.2 (mmol kg-1) / (mmol L-1)0.5. The readily exchangeable potassium (ΔK°) ranged from 0.007 to 0.737 with an average of 0.25 cmol kg^-1 and slowly exchangeable potassium (K^x) ranged from 0.023 to 0.55 with an average of 0.3 cmol kg^-1. Highly significant linear correlations were found (α=0.01) between PBC^k and CEC (r=0.66), AR° and exchangeable potassium percentage (r=0.76), AR° and solution potassium (r=0.89), and between ΔK° and exchangeable potassium (r=0.79). Because of high variations in physicochemical properties of soils, correlation coefficients between Q/I parameters and soil properties were not very high.

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The effect of soil salinity on plant growth is due to two factors, namely, increase in osmotic pressure of soil solution and the ionic composition of salt. The present experiment was conducted to obtain information about the response of pistachio (Pistacia vera L.) to salinity and ionic composition of the salt. Salinity with different relative composition of sodium chloride and sodium sulfate were applied to two pistachio cultivars, Fandoghi and Badami. Yield (dry matter of leaf and shoots produced in each pot) of plants were compared by the analysis of variances method of F and Duncan tests.

The yields of the cultivars were significantly different (P≤0.01) with Fandoghi cultivar producing less shoots and leaf and, consequently, lower total dry matter. Increasing the salinity level decreased the plant growth. Leaves were more sensitive to salinity. Increasing the ratio of sulfate salt alleviated the depressive effect of salinity such that when salinity was 100% sodium sulfate, the dry matter yield of shoots was 1.5 times and that of leaf was 1.7 times higher compared to the treatment where salinity was 100% sodium chloride. Leaf was more sensitive than shoots and, therefore, it showed a more positive response to chloride decreasing.

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In order to study the nectar quantity and quality of some onion cultivars and honeybees foraging activity on them, a complete randomized block design with three replications was conducted. Ten selected onion cultivars consisting of Ghom, Kashan, Azarshahr, Dorcheh, Tarom, Kazeroon 1, Kavar, Abarkooh, Hurand, and Yellow Sweet Spanish were used. Sixty mm mother bulbs of different onion cultivars were planted in 3×4 m plots on 6 lines. The distance between rows was 35 cm and plants were spaced 25 cm apart on each row. At flowering time, bees’ activity on the inflorescences was studied and flower nectar was collected in 10 micro-liter capillary tubes. Nectar volume was determined and analyzed. Mean numbers of honeybees visiting on inflorescence every 10 minutes and the mean residing time of each honeybee on a seed stalk (inflorescence) were significantly different in different cultivars. Hurand flowers had the least number of visitors and Dorche flowers had the longest visiting time. The amount of nectar varied in different cultivars, so did glucose (G), fructose (F), and sucrose (S) contents. Except for the Abarkuh cultivar that had more glucose than it had other sugars, all the cultivars had higher quantities of fructose than they had other sugars while sucrose had the least quantities among the sugars. Nectar sugar ratio in most of the cultivars was hexose dominant, which was identified by the low S/(F+G) ratio. Potassium, calcium, and sodium contents in nectar were different in different cultivars, too. Finally, the results showed that foraging activity of honeybees on onion inflorescences depends on the interactions of several factors such as nectar quantity and, more importantly, on sugar quantity and ratio as well as potassium content. .

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Rape seed (Brassica napus L.) containing more than 40 per cent oil is one of the best oilseeds for cultivation in Iran. Sclerotinia stem rot is one of the important diseases of the rape seed, the causal agent being Sclerotinia sclerotiorum. The aim of our study was to assess the effect of the disease on the quantity and quality of the extracted oil and remaining foodstuff in a field experiment. In this research three cultivars including Okapi, SLM046 and Talayeh were examined under field conditions using a factorial design (cultivars and inoculations were two factors under study). The cultivars were inoculated with SK₄ isolate of S. sclerotiorum. The inoculation was done on the plant stems at 30 cm height above the soil using Lewartosca method during mid flowering stage. One thousand- seed weight and glucosinolate, erucic and oleic fatty acids contents of the seeds were determind after the harvest. The results indicated that the infected plants in comparision with the controls had a lower 1000- seed weight and oleic acid content and a higher glucosinolates and erucic acid contents. There were significant differences among the genotypes in respect to all the studied traits except 1000- seed weight. Inverse correlation was observed between 1000- seed weight and erucic acid content or oil glucosinolates contents. It was concluded that the disease can reduce quantity and quality of seed oil and other nutrient contents.

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Pollination and fertilization of canola flowers are the main factors of canola seed production. In order to study the effects of insect pollinators on seed quantity and quality of three chosen cultivars of canola, namly, S.L.M., Okapi and Talaye, a split plot experiment in a complete randomized block design with four replications was carried out in Isfahan region. Main plots consisted of canola cultivars, and subplots consisted of open pollination and non-pollination by insects. Results indicated that the time to seed ripening in pollinated plots was 10.5 days less than those of non-pollinated plots. Pollination by insects increased the number of pods per plant, number of seeds per pod and weight of 1000 seeds, by 14.3%, 23.5% and 10%, respectively. Grain yield also increased by 53% in pollinated plots. Pollination decreased seed moisture percentage by 3.15%, but its effect on seed oil percentage and germination percentage were not significant. Time to seed germination of plants of pollinated plots decreased three hours. Cultivars were significantly different in seed oil percentage and time to seed germination. Talaye cultivar produced the highest amount of oil (45.5%), while Okapi produced the lowest (40.8%). There were significant interactions between cultivars and pollination in terms of seed ripening, oil percentage and moisture of seeds, and the effects of pollination was different in different cultivars.

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This research was conducted in order to select male genotypes of pistachio with good performance. The study was performed on 10 genotypes in regard to their flowering time, pollen quantity and quality. The results indicated that flowering times of P1, P2 genotypes were simultaneous with Kallehghochi P3, P4, P5 genotypes with Ahmad Aghaii P6 and P7 genotypes with Ohadi and P8, P9, P10 genotypes with Akbari. Inflorescence weight showed big differences between them, ranging from 4.5gr for P6 to 1.66gr for P8. The amount of pollen per inflorescence also showed big difference, ranging from 71mg for P2 and 267mg for P5. In order to determine the percentage of pollen germination, a medium consisting of sucrose, agar and boric acid was used. The percentage of pollen germination also showed big difference, ranging from 30%for P3 and P4 and 85% for P10. Stored pollen at 4°C temperature showed 30% germination after one month and 0% germination after three months. The results also indicated that the percentage of pollen germination in culture medium without boric acid was lower, compared with other treatments. The viability of pollens collected from cutting inflorescences kept in water bottle was higher than that obtained from dried inflorescences maintained in room condition.

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Successive cropping of potassium-demanding crops like sunflower leads to depletion of soil potassium (K). This study was conducted to investigate the different forms of K and quantity–intensity (Q/I) relationship for sunflower growing soils in Khoy region, West Azarbaijan province. Twenty composite soil samples were collected from different soil series. Different forms of K, including solution K (Kso), exchangeable K (Kex) and non-exchangeable K (Knex) were determined. The results showed that Kso values varied from 0.061 to 0.54 (mmol L-1), with an average of 0.28 (mmol L-1), Kav values ranged from 55 to 699 (mg kg-1), 265 mg Kg-1 on average, and Kex values ranged from 54 to 694 (mg Kg-1) with an average of 261 (mg kg-1). Furthermore, Knex values varied from 160 to 612 (mg kg-1), 261 (mg kg-1) on average. Available K (NH4OAc- extraction) was less than 250 mg Kg-1 in half of the soils indicating the depletion of potassium from these soils. The Q/I curves were predominantly located in the adsorption regions. The Q/I curves were linear and lacked the curvature part relating to loss and gain of potassium present in the specific sites. The PBCK values varied from 11 to 108 (cmolc kg-1)/ (mol L-1) 0.5 and an average of 38 (cmolc kg-1)/(mol L-1)0.5. There was a linear significant relationship between PBCK and CEC (r2=0.82***). The AReK values ranged from 0.0014 to 0.027 (mol L-1) 0.5 and 0.0076 (mol L-1)0.5 on average. There was a significant relationship between the values of AReK and those of the soil solution K (r=0.68**). The Ko values varied from 0.0050 to 0.49 cmolc kg-1and an average of 0.21cmolc kg-1. Additionally, there was a high significant relationship between the values of Ko and ARoK (r= 0.95***) in the soils under study.

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In order to map the genomic regions affecting barley forage quantity and quality, two experiments were conducted with 72 doubled haploid lines and their two parents (‘Steptoe’ and ‘Morex’), at the Research Farms of the Faculty of Crop and Animal Sciences, University College of Agriculture and Natural Resources, University of Tehran and Agriculture and Natural Resources Research Station of Sistan, in 2007. The experiments were arranged in a randomized complete block design with two replications. Each plot consisted of six rows that were 3m in length and spaced 25cm apart. QTL analysis was conducted by Composite interval mapping (CIM) method separately for each trait in each location. The main effect of genotype was high significant for all the studied traits. Transgressive segregation in both directions (positive and negative) was observed for all the studied traits. There was a negative relationship between forage qualityrelated with quantity-related traits. Thirty-three QTLs controlling different studied traits were identified. Phenotypic variance explained by these QTLs varies from 7.07 to 39.04%. Highest LOD scores were obtained for the leaf to stem ratio on chromosome 2H. QTLs of forage quality (total digestible nutrient, dry organic matter digestibility, leaf to stem ratio, seed to forage ratio and number of tiller per plant) and quantity (plant height, forage wet and dry matter) indexes were found on chromosomes 1H, 2H, 3H, 4H, 5H, 6H and 7H. Most of mapped QTLs appear to be fairly stable between locations and can become candidates for marker-assisted selection.

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Correlation between components of Q/I and wheat (Triticum aestivum L.) growth indices was studied in a greenhouse experiment during 2003-04 growing season. Eighty soil samples (0 – 30 cm depth) were collected randomly in farms around the Abyak region, Ghazvin province. Twenty-one samples were then selected based on soil texture and NH4OAC-K. The research included treatments of 21 soils and two potassium (K) levels (0, 100 mg/kg) and was conducted in a factorial manner in a randomized complete block design with three replications for studying correlations between Q/I and treatments. Effect of potassium application on the wheat growth was found to be significant at 5% level. The effect of soil properties on wheat growth was also found to be significant at 1% level. However, the interaction of K and soil was not significant. There were no significant differences among the different equilibrium time intervals. The soil potassium buffering capacity (PBCK) values were strongly correlated with CEC (r =0.996**), clay content (r = 0.921**) and moisture saturation percentage (r = 0.811**). Final equation derived from stepwise regression for prediction of PBCK was as follows: PBCK = 7.419 CEC –19.743 R2adj = 0.782** The equilibrium potassium activity ratios (ARke) were strongly correlated with soluble potassium (r =0.846**), NH4OAC-K (r =0.730**), SP (r = 0/794*), OC (r = -0.477ns) and clay content (r=-0.602*). Similarly, readily exchangeable potassium (ΔK0) was strongly correlated with ammonium acetate extractable potassium (r = 0.871**), soluble potassium (r = 0.778**), saturation percentage (r = 0.551*), organic carbon percentage (r=-0.045ns) and clay content (r=-0.206ns). There was no significant correlation between ΔK0 and ARKe with potassium uptake values by wheat. In contrast, there was a strong correlation between PBCK values and potassium uptake by wheat (r = 0.729**), and relative wheat yield (r = 0.735**). There was no significant correlation between Q/I parameters when KCl and K2SO4 were used, and the soil physicochemical properties. However, Q/I parameters obtained from KCl showed a higher correlation with wheat plant's growth indices.

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Soil characteristics are affected by climate. Available potassium is one of the most important soil fertility indices. This study was conducted to determine the availability of potassium using Quantity- Intensity (Q/I) relationships in Vertisols of Isfahan and Chaharmahal-Va-Bakhtiari provinces with aridic and xeric moisture regimes, respectively. Soil mineralogy showed that smectite was the dominant clay in Chaharmahal-Va-Bakhtiari soil. The results showed that the activity ratio of K (AReK) in the soil solution of the surface soil in Isfahan and Chaharmahal -Va -Bakhtiari soils, ranged from 0.019 to 0.11 and 0.0037 to 0.0078 mmol.L-1 respectively. The labile K (∆K0) in Isfahan and Chaharmahal Va Bakhtiari soils ranged from 0.23 to 3.8 and 0.72 to 1.6 mmolkg-1, respectively. Potassium on specific sites (KX) in Isfahan and Chaharmahal-Va-Bakhtiari soils ranged from 2.8 to 7.1 and 2.6 to 3.7 mmolkg-1 respectively. The potential buffering capacity (PBCK) in Isfahan and Chaharmahal-Va-Bakhtiari soils ranged from 12 to 36 and 191 to 201 mmolkg-1/(mmolL-1)0.5 respectively. The results suggested that the Q/I parameters were affected by soil depth. In all of the soils studied, PBCK increased with soil depth.

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Quantity-Intensity (Q/I) curves and their derived parameters provide general information about soil Potassium (K) availability. This investigation was conducted to obtain K different varieties and their correlations with K, Q/I parameters in 13 soils sample from Bahar area as the major potato producing area in Iran. Soil Samples were equilibrated with solution containing different potassium activity ratios (ARK), and changes in potassium concentrations in the equilibrium solution (ΔK) were ploted against activity ratio of K, and Q/I parameters were determined. The results showed that, potassium activity ratio at equilibrium (AR0) ranged from 0.007 to 0.995 with an average of 0.16 (mmol L-1)0.5, The readily exchangeable potassium (ΔK0) ranged from 0.04 to 2.199 with an average of 0.49 cmol kg-1, The potassium potential buffering capacity (PBCK) ranged from 13.21 to 75.37 with an average of 42.02 (mmol kg-1) / (mmol L-1)0.5. Highly significant linear correlations were found between PBCK and CEC (r = 0.6*), AR0 and KSO (r = 0.99**), AR0 and Kex (r = 0.85**). Among the studied soils, one soil (Chopolgh Lo soil) absorbed potassim on edge position of clay minerals and the others absorbed potassium on planar surface.

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