Effect of different rootstocks on Kinnow mandarin [Citrus nobilis Lour x Citrus deliciosa Tenora]

Abstract

Present investigation was carried out to study the root morphology of one year old seedling and the influence of different rootstocks in pre-bearing Kinnow mandarin under field condition on plant morphological, physiological, tissue nutrients and biochemical parameters at the Division of Fruits and Horticultural Technology, I.A.R.I., New Delhi during 2014-15. Results of the findings revealed that the seedling rootstock of rough lemon had a better root morphology with respect to root length (1511.27cm), projected area (158.42cm2 ), surface area (482.00 cm2 ), root volume (12.24 cm3 ) and the number of forks (7026.80) with a comparatively inferior root morphology in Carrizo. Comparative performance of budded Kinnow on different rootstocks showed that trees on Jatti Khatti were superior in terms of stimulated increase in plant height (49.42%) and canopy volume (22.56%) during the period April-September, compared to minimum enhancement in Kinnow trees on Troyer citrange during the same period. Kinnow trees on different rootstocks maintained congenial relationship with the scion closest to 1.0. Leaf sclerophylly in terms of leaf area, fresh mass, dry matter and density of foliar tissue was higher in Jatti Khatti but leaves more succulent on rough lemon. Kinnow leaves on Karna Khatta and rough lemon maintained significantly higher relative water content (88.61%). However, chlorophyll fractions was higher in leaves on rough lemon with reduced chlorophyll fractions on Carrizo rootstock. Higher physiological activity in terms of photosynthetic rate, stomatal conductance, and internal CO2 was recorded in scion leaf of Kinnow on rough lemon during summer and during autumn and winter on Jatti Khatti and rough lemon. Leaf N and P content was higher in leaf tissue on sour orange while K, Ca and Mg content was higher in leaf tissue on rough lemon. Sodium accumulation in leaves was higher in Rangpur lime as compared to Troyer which accumulated minimum sodium. Leaf tissue of Sour orange excelled in micronutrients and maintained higher Fe, Zn, Mn and Cu in their leaves. Kinnow scions on rough lemon exhibited higher enzyme activities with respect to total soluble protein, 64 superoxide dismutase, peroxidase, and glutathione reductase activity, while catalase activity was significantly higher on sour orange rootstock. Proline accumulation was also observed to be higher on sour orange rootstock. Scion leaf on Troyer rootstock accumulated 1.88 fold more phenol. Polyphenol oxidase activity was observed higher in scion leaves on Jatti Khatti with minimum activity on Troyer and Carrizo citrange rootstock. From the findings of this study, it is concluded that rough lemon rootstock imparted higher metabolic activity in Kinnow scion, while sour orange accumulated more nutrients in their tissue. Carrizo proved to be an inferior rootstock with most of the characters studied.