Tree age influences nutritional, pectin, and anatomical changes in developing ‘Kinnow’ mandarin (Citrus nobilis Lour × Citrus deliciosa Tenora) fruit

ABSTRACT

An understanding of variation in fruit quality in relation to tree age can help understand the issue of poor fruit quality in young orchards; however, limited information is available on the citrus fruit. In this study, the endogenous nutritional status in rind, rag, and leaves; pectin status in rind and rag; and anatomical fruit growth parameter in rind tissues were studied in ‘Kinnow’ mandarins fruit during their development on trees from three age (6-, 18-, and 35-year-old) groups. In older (35-year-old) trees, rind, rag, and leaf nitrogen (N), phosphorus (P), and potassium (K) concentrations were superior. In fruit from all tree age groups, total pectin and protopectin reduced; however water-soluble pectin (WSP) improved. In rind tissues harvested from young (6-year-old) trees, cell density was more while cell size was less. In all tree age groups, cell density in rind tissues correlated negatively with rind WSP.

KEYWORDS:

• cell density
• cell size
• endogenous nutrients
• fruit growth and development
• ‘kinnow’ mandarin
• tree age

Abbreviations

Ca	=	Calcium
DAFS	=	Days after fruit set
F:A:A	=	Formaldehyde:acetic acid: alcohol
Fe	=	Iron
K	=	Potassium
Mn	=	Manganese
N	=	Nitrogen
P	=	Phosphorous
PP	=	Protopectin
TP	=	Total pectin
WSP	=	Water-soluble pectin

Acknowledgments

The principal author gratefully acknowledges the financial support of Higher Education Commission (HEC) of Pakistan in the form of Indigenous 5000 Scholarship Scheme and International Research Support Initiative Program (IRSIP) for training and conducting a part of research at Curtin University. I would like to thank Ms. Susan Petersen, Senior Technical Officer at Curtin University, Perth, Australia. I would like to express my special thanks to Dr. Muhammad Zargham Khan, Chairman/Professor, Department of Pathology, Faculty of Veterinary Sciences, University of Agriculture Faisalabad for allowing me to use laboratory facilities to conduct anatomical studies.

Additional information

Funding

The principal author gratefully acknowledges the financial support of Higher Education Commission (HEC) of Pakistan in the form of Indigenous 5000 Scholarship Scheme and International Research Support Initiative Program (IRSIP) for training and conducting a part of research at Curtin University, Perth, Australia.