Parthenocarpy induction, pollen germination and pollen tube growth of ‘Montenegrina’ mandarin

Abstract

The objective of this work was to determine the effect of different combinations and concentrations and number of applications of GA₃ , CuSO₄ and NAA in pollen germination in vitro, tube growth in flowers treated individually, and field parthenocarpy induction of self compatible ‘Montenegrina’ mandarin. Pollen was collected and added to culture medium with nine treatments composed by different doses and combinations of the three products. Flower buds previous to anthesis were selected and treated with NAA (200 mg l^-1), GA₃ (100 mg l^-1), GA₃ + CuSO₄ (100 mg l^-1 c/u), CuSO₄ (100 mg l^-1) and untreated control. At 0, 5 and 10 days post-application the flower buds were collected, and pollen tube growth was measured with fluorescence microscope. Under field conditions 30 trees were selected and five treatments were applied: CuSO₄ (100 mg l^-1) one and two applications, GA₃ (100 mg l^-1) one and two applications and control. All treatments applied to the culture medium inhibited in vitro pollen germination and tube growth in individual flowers compared to the control. Ten days after application pollen tube grew no further than 30% of the style in any of the treatments and GA₃ (100 mg l^-1) limited its growth in the stigmatic area. Among the treatments, the only one that was efficient treatment was GA₃ double applications, which reduced from nine to seven the number of seeds per fruit compared to the control.