عنوان مقاله [English]
Introduction Production of pistachio is not often economical as located mainly in saline-sodic soils. Amendments such as gypsum and sulfur are cheap and convenient available. Gypsum can introduce calcium to the soil and replace exchangeable sodium and sulfur with production sulfuric acid and then pH reduction will increase the availability and absorption of plant nutrients from soil. Humic acid can also improve physical, chemical and biological soil properties and stimulate growth via its effects on plant metabolism. Therefore, the objective of this research was to study the influence of gypsum, sulfur and humic acid on some properties of pistachio leaves and some soil properties.
Materials and Methods A field experiment was accomplished as a randomized complete block design in two years (split plot) with three replications in Izadyaran Company (30 km south of Sirjan). Treatments were consisted of two chemical amendments (gypsum and sulfur, 10 Mg ha-1) as main plot factor and methods of HUMAX applications (control, soil application 40 L ha-1, and foliar application 2.5 L ha-1), as subplots. Analysis of variance was performed by multiplex analysis. Chemical matters were poured in to the pit of planting and mixed thoroughly with soil and an one-year-pistachio seedling was planted (February 2012) Then three months after planting, HUMAX was applied (June 2012). HUMAX application was repeated in the following year (June 2013). Leaf sampling and soil sampling for the measurement of some leaf and soil properties were performed in the middle of summer (August 2012 and 2013) and at the end of winter (February 2013 and 2014), respectively.
Results and Discussion Results showed that over a year, the amount of chlorophyll-a, carotenoids and leaf K declined (p<0.05), while first two features increased with sulfur. Gypsum application increased chlorophyll-a and leaf K. Soil application of HUMAX was able to increase the amount of chlorophyll-b and leaf P. The effective combination was sulfur and soil application of humic acid in the second year that significantly increased chlorophyll-b and carotenoids, while none of them decrease leaf N, P, K. At the end of the first year the electrical conductivity, cation exchange capacity decreased, whereas soil pH and N increased. Sulfur reduced bulk density, the mean weight diameter and water aggregate stability but increased EC. Soil application of HUMAX reduced bulk density and water aggregate stability while sulfur usage plus foliar application of HUMAX caused the greatest mean weight diameter. The highest CEC value was recorded in foliar application of HUMAX and gypsum treatment. Due to the high buffering properties of soil, none of the treatments had significant effect on soil pH. None of the interaction effect on soil N, labial P and available K.
Conclusion The findings of this study showed that one of the best combinations for increasing the some physiologic properties of pistachio leaf were sulfur plus soil application of HUMAX especially with passing the time. Leaf K and P increased with gypsum and soil application of HUMAX. Sulfur application improved bulk density, mean weight diameter and water aggregate stability. Electrical conductivity can be reduced with time and soil N increased.