Effects of Temperature and the Combination of Liquid Lime Sulfur and Fish Oil on Pollen Germination, Pollen Tube Growth, and Fruit Set in Apples

Abstract

<jats:p>Effects of temperature and the combination of liquid lime sulfur (LLS) and fish oil (FO) applied during bloom on pollen germination and pollen tube growth in flowers and fruit set were examined in apples (<jats:italic>Malus</jats:italic> ×<jats:italic>domestica</jats:italic> Borkh.). Percent germination of pollen of ‘Manchurian’ crabapples and ‘Golden Delicious’ apple flowers on the stigmatic surface of ‘Golden Delicious’ pistils increased with increasing temperature from 13 to 29 °C in the first 24 and 48 h after pollination, respectively, but not thereafter. Pollen tube growth rate in the style increased quadratically with increasing temperature from 13 to 29 °C. ‘Manchurian’ was a more effective pollenizer of ‘Golden Delicious’ than was ‘Golden Delicious’ pollen. For example, at 24 or 29 °C, some ‘Manchurian’ pollen tubes grew to the base of ‘Golden Delicious’ styles by 24 h after pollination. On the other hand, no ‘Golden Delicious’ pollen tube grew to the base of a ‘Golden Delicious’ style regardless of temperature and time. Pollen tube growth rate in the style increased with increasing day/night temperature from 7/0 to 24/7 °C. The time required for pollen tubes to grow to the base of styles decreased with increasing day/night temperature from 13/2 to 24/7 °C. Only ≈36 h was required for pollen tubes to grow to the base of style at 24/7 °C, whereas pollen tubes grew very slowly and no pollen tubes grew to the base of style at 7/0 °C regardless of pollen source. LLS + FO, applied 4 or 24 h after pollination, inhibited pollen germination, pollen tube growth in the style, fertilization, and fruit set, but it had no effect when applied 48 h after pollination. These results suggest that LLS + FO applied at this bloom stage causes flower or fruit abscission most likely by inhibiting pollen germination, pollen tube growth in the style, and fertilization.</jats:p>

Effect of Spraying Fish Oil and Glutathione on Fruiting of Ewaise Mango Trees Grown under Sandy Soil

“…These results regarding the beneficial effects of fish oil on growth and fruiting of Ewaise mango are in harmony with (Olmo et al, 1981;Osnaya and Schlasser, 1998;Mc-Arthey et al, 2006;Yoder et al, 2009;Masoud and Abou-Zaid-Eman, 2017).…”

“…Using fish oils was responsible for promoting growth tree nutritional status, yield and fruit quality of different horticultural crops (Olma et al, 1981;Osnaya and Schlasser, 1998;Mc-Arthey et al, 2006;Yoder et al, 2009;Masoud and Abou-Zaid-Eman, 2017).…”

Pollen Tube Growth and Fruit Set in Apple

“…Pollen was tested in the laboratory in petri dishes before pollination to examine viability. Following the methods of Yoder et al (2009), pollen was placed on a medium of 1% agarose, 10% sucrose, and 10 ppm boric acid at room temperature for 24 h. The proportion of germination was visually observed under a light microscope. All pollen used in these experiments had high germination rates (>80%).…”

“…The methods of Yoder et al, (2009) were modified to evaluate pollen germination on the stigmatic surface, number of pollen tubes penetrating the stigma, the length of the longest pollen tube growing down the style, and number of pollen tubes that reached the base of the style. Briefly, five hand-pollinated flowers were collected from each treatment at one, two, three, and four DAP.…”

“…They reported that 'Spartan' pollen had a higher germination percentage than that of 'Cox's Orange Pippin' at 8 to 10°C and 'Idared' at 14 to 16°C. Linear correlations between pollen germination on the stigmatic surface and temperature were reported from 13 to 29°C (Yoder et al, 2009) and from 6 to 33.5°C (Jefferies and Brain, 1984).…”