Morphological and Floral Characterization of Some Citrus Rootstocks

Abstract

The study was carried out on five different citrus rootstocks viz. rough lemon (Citrus jambhiri Lush.), trifoliate orange [Poncirus trifoliata (L.) Raf.], rangpur Lime (Citrus limonia Osbeck.), Carrizo citrange [Citrus sinensis (L.) Osbeck. x Poncirus trifoliata (L.) Raf.] and Swingle citrumelo [Citrus paradisi Macf. x Poncirus trifoliata (L.) Raf.] at Punjab Agricultural University, Ludhiana. The plants were evaluated for 20 quantitative and 11 qualitative characters as per Descriptor of Citrus. Variability was observed among different genotypes for tree, leaf and flower characters. Trifoliate orange, Carrizo citrange and Swingle citrumelo were deciduous where as rough lemon and rangpur lime were evergreen. Tree shape was obloid in rangpur lime and ellipsoid in all the other rootstocks. Tree growth habit also varied from erect in trifoliate orange, Carrizo citrange and Swingle citrumelo and spreading type in rough lemon and rangpur lime. Spine shape was curved in case of trifoliate orange and straight in all other rootstocks. Leaf division was unifoliate in rangpur lime and rough lemon where as it was trifoliate in case of trifoliate orange, Carrizo citrange and Swingle citrumelo. Leaf lamina shape was observed lanceolate in Swingle citrumelo, ovate in Carrizo citrange and trifoliate orange; and elliptic leaf lamina was observed in rangpur lime and rough lemon. Maximum leaf lamina length and width (76.33 mm and 44.47 mm, respectively) were recorded in rough lemon and minimum leaf lamina length (45.64 mm) and width (21.92 mm) was recorded in Carrizo citrange. The spine length ranged between 13.33 to 46.67 mm in all the rootstocks. Among the different rootstocks, Swingle citrumelo was the earliest to flower (February 24) while rangpur lime was last to flower (March 17). Swingle citrumelo was the earliest to attain full bloom (February 28 to March 4) among all the rootstocks. While rough lemon and rangpur lime was the last to reach full bloom (March 22 to 26). The rootstocks also differ with respect to end of flowering. Among different rootstocks the flowering season terminated earliest in Swingle citrumelo (March 19) whereas, in rough lemon flowering ended at the last on 24th April.