Montenegrina Mandarin: Characterization of the Agronomic Behaviour and Fruit Size Improvement
Montenegrina mandarin (Citrus deliciosa Ten.), a spontaneous mutation of the common mandarin, originated in Montenegro, Brazil. Under Uruguayan conditions, fruit ripen approximately one month later than common mandarin and have fewer seeds,allowing for higher prices. However,small fruit size often limits its economic potential. The objectives of this work were to characterize the agronomic behaviour and to improve final fruit size in the South of Uruguay. Sprouting and flowering intensity, fruit set and growth,final fruit size and quality were evaluated during two years in plants with different crop loads. Different treatments were applied during two consecutive years; gibberellic acid (40 mg/L) at the floral induction period and three synthetic auxins (2,4-DP,75mg/L ; NAA,225mg/L and 3,5,6-TPA, 10 or 20mg/L)at different times during stage I of fruit development. A typical alternate bearing with flowering intensities from 2 to more than 60 flowers per 100 nodes, in off and on conditions respectively, were found in this variety. A high percentage of nodes with two or more shoots per node and a high percentage of single leafy and leafless flowered shoots were found. Final fruit set varied from 4％ to 50％ for trees with high and low flowering intensity, respectively. Winter GA3 application significantly reduced flowering intensity and consequently, final fruit set dramatically increased, resulting in too many fruit per plant. Foliar-application of 2,4-DP and NAA 35 days post flowering showed non-consistent results between years. A reduction of 50％ of the fruit number with significant increase in fruit size was found the first year,but no response could be seen in the second one. Application of 3,5,6-TPA (10mg/L) at the same phenological stage thinned 90％ of the fruit. This auxin sprayed at the end of the fruits physiological drop (fruit diameter 13 - 16mm) significantly increased the percentage of marketable size fruit. Internal quality (juice percentage, TSS, tritatable acidity) was not affected by any treatment. The alternate bearing of this variety verified in this work could not be overcome with winter GA3 sprays due to excessive fruit set. Application of 3,5,6-TPA at the end of physiological drop seems to be the most promising practice to improve fruit size in the on year, with a slight reduction in fruit number.
Citrus deliciosa Flowering Fruit set Growth regulators
G. Gambetta M. Espino E. Pardo V. Alberti H. Arbiza A. Gravina
Departamento de Produccion Vegetal, Facultad de Agronomia, Universidad de la Repiiblica. Garzdn 180, Montevideo 12900, Uruguay
国际会议
11th International Citrus Congress(第11届国际柑橘大会)
武汉
英文
561-566
2008-10-01（万方平台首次上网日期，不代表论文的发表时间）