Effects of 2,4-DP- P (2,4-Dichlorophenoxypropionic Acid-P) Plant Growth Regulator on Fruit Size and Yield of Star Ruby Grapefruit (Citrus paradisi Osb.)

Abstract

Star Ruby is the main grapefruit (Citrus paradisi) variety grown in Turkey; however, small fruit size is a common problem in ‘Star Ruby’ grapefruit. Fruit size is a decisive external quality parameter in citrus at the marketing of fresh citrus fruits. Fruit size can be enhanced by several techniques such as girdling and thinning. Various plant growth regulators are known to affect the growth and size of citrus fruit. The objective of the present study was to observe the effects of 2,4 dichlorophenoxypropionic acid-p (2,4-DP-P) on the fruit size, yield and quality of Star Ruby from 20-year-old trees budded on sour orange rootstock in Adana, Turkey in 2007. Four concentrations (50, 100, 150 and 300 ppm) of 2,4-DP-P were applied 8 weeks after anthesis during physiological fruit drop when the mean fruit diameter was 13-15 mm. The results indicated that the application of 2,4-DP-P increased the fruit size of Star Ruby grapefruit without reducing yield. The application had a significant effect on fruit yield except for trees treated with 50 ppm 2,4-DP-P. Compared with the control trees, applications of 2,4-DP-P increased the number of large, commercially valuable Star Ruby (>93 mm, 89-93 mm and 84-89 mm). No effects were determined on fruit internal quality parameters. Thus, the results of the present study revealed that 2,4-DP-P can be used to improve the fruit size of Star Ruby fruitlets during the June drop.

Producción y calidad de fruto de limón persa (Citrus x latifolia Tanaka ex Q. Jiménez) en la época invernal con mantenimiento de diferentes tensiones de humedad del suelo

“…Para aumentar la producción de limón persa en la época invernal en México, se han estudiado varias prácticas como el uso de hormonas, estrés hídrico, fertilización y anillado, en tratamientos solos y combinados, con resultados promisorios (Almaguer-Vargas et al, 2011;Ambriz-Cervantes et al, 2018) siendo el estrés hídrico, una las prácticas más utilizadas en los subtrópicos y trópicos para inducir floración en la época invernal (Ariza et al, 2004). En términos de rentabilidad, la calidad de la fruta se ha convertido tan importante como el rendimiento (Yılmaz et al, 2018). El tamaño, forma, color, carencia de defectos, cantidad de jugo y sabor, son algunos de los atributos de calidad que pueden verse afectados por las prácticas culturales usadas para desfasar la cosecha (Almaguer-Vargas et al, 2011;Arévalo et al, 2016).…”

Phenological Characteristics of Potted Kumquat under Protected Culture

“…In Meiwa kumquat (Fortunella crassifolia Swingle), drought stress was positively correlated with flowering (Iwasaki et al, 2000;Ono et al, 2010;Iwasaki and Hiratsuka, 2019); moreover, sugars that accumulate in the xylem play a critical role in osmoregulation . Since the economic value of small-fruited citrus varieties is far lower than that of the large-fruited citrus, there has been less research on kumquat than on sweet orange or grapefruit (Fadela et al, 2018;Lado et al, 2018;Yilmaz et al, 2018). However, due to the high nutritional value and multi-utility of kumquat and the works we had have done (Chang et al, 2014(Chang et al, , 2015, the growth characteristics and cultivation of kumquat need further investigation.…”