Effects of Lime Sulfur and Fish Oil on Pollen Tube Growth, Leaf Photosynthesis and Fruit Set in Apple

Abstract

<jats:p>The effect of liquid lime sulfur (LS) and fish oil (FO) application during bloom on leaf photosynthesis (Pn) and pollen tube growth in apple (<jats:italic>Malus</jats:italic> ×<jats:italic>domestica</jats:italic>) flowers were investigated in order to determine their mode of action as a bloom thinning agent. LS increased the percentage of flowers with fewer than 10 pollen tubes per flower to more than 64% compared to 5% or less in the control. Pollen tubes were completely absent from 27% to 48% of flowers following LS treatment compared with fewer than 4% of flowers having no pollen tubes on control trees. These data indicate that 30% to 50% of flowers that open on the day of LS application are unlikely to set a fruit due to the complete inhibition of embryo fertilization. Increasing the rate of LS from 0.5% to 4% increased the proportion of flowers with limited pollen tube number in a concentration dependent manner. LS suppressed the rate of light saturated Pn; successive LS sprays during the bloom period had an additive effect on suppression of Pn and fruit set. In one study the reduction in Pn was greatest 12 days after application of LS but Pn recovered by about 19 days after initial treatment. In a second study Pn of primary spur leaves had still not recovered when measured 57 days after the first of three applications. FO had no effect on the number of pollen tubes per flower, but reduced Pn and fruit set by about 10% and 20% respectively. An increase in the proportion of flowers with no pollen tubes, and therefore no embryo development, can account, at least in part, for the thinning response following application of LS to apples during bloom. It is likely that suppression of Pn contributes to the thinning response, although the importance of this mechanism will depend on perturbation of the total carbohydrate supply to developing fruit.</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).…”

Blossom Thinning in Apple and Peach with an Essential Oil

“…Young spur apple leaves play a vital role in supplying the developing fruits with carbohydrates (Corelli Grappadelli, 2003) and in fruit retention (Ferree and Palmer, 1982). A reduction in Pn after application of caustic materials at bloom (McArtney et al, 2006;Noordijk and Schupp, 2003) or from shading or Pn inhibitors (Byers et al, 1990a(Byers et al, , 1990b has been suggested as a causal factor in fruit thinning (Byers, 2003). Injury to spur leaves or shading followed by reductions in Pn could reduce fruit size.…”

“…Dormant spray oils have been shown to reduce Pn in apple leaves (Ferree and Hall, 1975) and en-hance the thinning activity of mild chemical thinners . McArtney et al (2006) reported that liquid lime sulfur (LS) and fish oil applied at bloom time suppressed Pn and likely contributed to the thinning response of these materials.…”

Dust Interferes with Pollen–Stigma Interaction and Fruit Set in Pistachio Pistacia vera cv. Kerman

“…The female flower's acidic stigmatic secretions that facilitate pollen hydration and germination can also be damaged by alkaline dust (Sett, 2017). McArtney et al (2006) reported sulfur liming at bloom inhibited pollen tube growth and subsequently reduced fruit set in apple (Malus domestica).…”