نوع مقاله : مقاله پژوهشی
نویسندگان
1 بخش تحقیقات خاک و آب، مرکز تحقیقات کشاورزی و منابع طبیعی استان فارس، سازمان تحقیقات، آموزش و ترویج کشاورزی، شیراز، ایران.
2 بخش علوم خاک، دانشکده کشاورزی، دانشگاه شیراز، شیراز، ایران
3 بخش تحقیقات خاک و آب، مرکز تحقیقات و آموزش کشاورزی و منابع طبیعی صفیآباد، سازمان تحقیقات، آموزش و ترویج کشاورزی (AREEO)، دزفول، ایران
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
Introduction: Date palm (Phoenix dactylifera L.) is one of the most valuable domesticated fruit trees in Iran due to its significant importance in economy, societies, health benefits and production capacity in unfavorable semi-arid and arid regions. Iran has more than 30 million date trees in 216,000 hectares, which produce 900,000 tons of date products. Bushehr province is one of the main origins of dates and one of the producers of dates in the south of Iran. Considering the importance of dates in Bushehr province, this study was conducted with the aim of investigating the pattern of spatial changes in surface and deep soil characteristics and its effect on date performance.
Materials and Methods: This research was carried out in a large area about 39000 ha in Shabankareh region which is located in Bushehr province in southern Iran with old and new date palm gardens. Kabkab is the dominant date palm cultivar in the region. At first, the boundary of study area was determined by satellite pictures obtained from Google earth program. Then, target gardens were selected through visual differences between trees crown spread and garden density as a sign for their growth abilities. Field surveys were also accomplished to fulfill and check the selected gardens from close. Study area was spread from slope plain with 110 meters height in north part to the medium slope in center and flat plain in the south-west of region with 50 and 15 meters height, respectively. Soil samples were taken from three layers (0-30, 30-60 and 60-90cm) of target garden soils with auger and then was analyzed in laboratory. Soil properties such as texture, pH, electric conductivity of extract (EC), catain exchange capacity (CEC), equivalent calcium carbonate (CCE), organic carbon percent, macro and micro nutrients (N, P, K, Fe, Mn, Cu, Zn), gypsum and saturation percent. Date palm yields were weighing from three plants randomly in any target garden under the permission of garden owner who was also asked about the fertilizer and irrigation management of his garden, as well. Descriptive analysis of measured data was done by SPSS as well as their person correlations. Geostatistical analysis for soil properties and yield was carried out by GS+ to study the spatial variation of the measured properties. Yield zoning was then mapped for the survey area as a result of studied production spatial variance by Kriging estimator.
Results and discussion: Linear stepwise regressions for soil properties with date palm yield in three soil depth layers (0-30, 30-60 and 60-90cm) were calculated. Adjusted R2 were 0.24, 0.89 and 0.76 for the layers, respectively. The highest correlation (0.89) was related to the second layer which is known as nutritional zone and contains the highest proportion of primary and secondary roots to uptake nutrients from soil solution. Only K played a significant role in regression equation of the first layer which is called respiratory zone and most of its roots have a negative geotropism and play a respiratory role. The highest Pearson correlation coefficient (0.61) obtained for N macronutrient due to all year long continuity of vegetative growth stage in date palm. Yield correlation was negative with some of soil properties such as pH, gypsum, Ec, CCE and sand. Higher acidity of soil results fixation of micronutrients. More gypsum and EC in soil tends to high osmotic pressure that disorders roots water uptake. Sand has lower water content capability and its high percentage in soil causes water stress for plants.
Conclusion: large parts of Iran are expecting to be planted by date palm in future because of climate change and also date palm high tolerance to environmental stresses such as droughness and saline conditions. It's very important to achieve correct information about soil properties which can influence date palm yield in order to figure out deficient or excess amount of these properties in the region for improving cultivation managements. Nitrogen is more important than K and P for date palm especially in semiarid and arid regions. Soil layer between 30 to 60 cm is the best depth for applying fertilizers to be well up taken. Drowind yield zoning map of the area showed the best parts for date palm cultivation and can be used for other similar environments.
کلیدواژهها [English]
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