Effect of thinning practices on some physical, physiological characteristics, mineral elements and bunch fading disorder in Bam district

Bunch fading disorder is one of the important problems in date palm orchards in Iran and influences the quantity and quality of fruits. The aim of this study was investigating the effect of bunch thinning as a management factor on bunch fading disorder, as well as physical, physiological and chemical characteristics of Mazafati date. The experiment was carried out in a randomized complete block design. Four bunch thinning treatments included: T1, shortening of 1/3 total strands from terminal tips in pollination stage (1/3 tippol); T2, removal of 1/3 total strands in kimri stage (1/3 skim); T3, shortening of 1/3 total strands from terminal tips in kimri stage (1/3 tipkim); T4, removal entire of some bunches (traditional thinning as control). Some physical (percent of faded bunches, percent of faded fruits, fruit’s weight, fruit’s length and diameter), physiological (fruit’s proline, total carbohydrates, superoxide dismutase and guaiacol peroxidase enzymes) and chemical (potassium and phosphorus) characteristics of date palms were determined. The results indicated that the percent of faded bunches and fruits in 1/3 tippol and 1/3 skim treatments significantly (P≤0.05) decreased as compared to control. Treatments of 1/3 tippol and 1/3 skim significantly (P≤0.05) increased fruit’s weight (30%), fruit’s diameter (18%), proline (69%), superoxide dismutase (SOD) enzyme (90%) and potassium (K) (13%) as compared to control. It can be concluded that 1/3 tippol and 1/3 skim thinning treatments noticeably decreased bunch fading disorder. Shortening of 1/3 total strands from terminal tips in pollination stage is recommended to date palm owners of the region, due to the concurrency of thinning and pollination stage.