Meio de cultura para germinação de grãos de pólen e paclobutrazol em cultivares de oliveira

Abstract

The objective of this work was adjust the basic culture medium, for germination of pollen grains, to determine the pollen germination capacity, to quantify the number of pollen grains per flower of different cultivars of this species and check the vegetative and anatomical changes of olive cultivars submitted to different doses of paclobutrazol (PBZ). The first experiment was conducted in Maria da Fé city, MG. To determine the culture medium, five sequential experiments were performed according to the following steps: 1) agar concentrations (4, 6, 8 and 10 g.L-1) and boric acid (0, 400, 800 and 1200 mg.L-1); 2) pH values (3.5, 4.5, 5.5 and 6.5) and sucrose concentrations (0, 30, 60 and 90 g.L-1); 3) Calcium nitrate concentrations (0, 200, 400 and 800 mg.L-1) and magnesium sulphate (0, 0.5, 1 and 1.5 mg.L-1); 4) incubation temperature (24, 26, 28, 30 and 32 °C) and 5) incubation time (0, 12, 24, 36, 48, 60 and 72 hours). A completely randomized design being used, with four replications. To determine the rate of germination of pollen was used DIC with 28 treatment and four replications. To evaluate the number of pollen grains per flower was used DIC with 28 treatments and five replications. The culture medium must be composed of 4 g.L-1 agar, 90 g.L-1 sucrose, 400 mg.L-1 of boric acid and pH adjusted to 5.79 in the absence of calcium nitrate and magnesium sulfate, maintained for 60 hours at 28 ° C. The ‘Manzanilla 215’ showed higher germination and ‘Ascolano 315’ showed the highest number of pollen grains per flower. The second experiment was conducted in Maria da Fé and Lavras citys, MG. The statistical design was DIC in factorial 2 [cultivars: Arbequina and Ascolano 315 (ASC 315 MGS)] x 4 (doses: 6, 12 and 18 mL.planta-1 PBZ, plus the control) with three replications. Were evaluated growth in height and diameter, dry mass of shoots and roots, content of chlorophyll a, b and total, thickness of the adaxial and abaxial epidermis and palisade and spongy parenchyma. In Lavras, the ‘Ascolano 315’ showed less growth in height. Paclobutrazol reduced height, diameter and leaf dry mass of the root system of plants grown in Maria da Fé. The content of chlorophyll a, b and total has not changed with the application of PBZ, however in Lavras the ‘Ascolano 315’ showed a higher content of chlorophyll in Maria da Fé, ‘Arbequina’ higher concentrations of chlorophyll a, b and total. The ‘Arbequina’ was more influenced by the effect of PBZ. The ‘Ascolano 315’, had its abaxial reduced by 52.16% when subjected to the application of 10.32 g.plant-1 PBZ. The ‘Arbequina’ showed higher thickness of palisade and spongy parenchyma.