Handbook of Plant and Crop Physiology

(Steven Felgate) #1

and individually transferred to test tubes filled with water. Three cuttings were used for each set, and each
set was repeated three times for confirmation. The observations were recorded after a definite interval of
time. Measurements of bud sprouting, number of leaves, inflorescence, and root initiation were observed
in the cultivated variety (Table 3).
The lower concentration (10 ppm) of IAA led to a better response than the higher one (20 ppm). At
10 ppm the bud sprouting was 100%, whereas with 20 ppm it diminished to 4. Leaf initiation and inflo-
rescence followed the same trend as the bud sprouting, being 8 and 11, respectively, in 10 ppm, and 8 and
6, respectively, in 20 ppm.
Similar results were obtained in NAA, with 100% bud sprouting in 10 ppm, slightly more than in
IAA, being 5. Leaf initiation and inflorescence were also higher in 10 ppm compared with 20 ppm, being
9, 9, 8, and 5, respectively.
IAA again showed a beneficial effect at the lower concentration (10 ppm) as compared with the
higher (20 ppm), producing 7 and 4 buds, respectively. Leaf initiation increased from 7 to 10 with in-
creasing concentration, but the inflorescence did not show any change (Table 4).
The results with NAA showed effects similar to those with IAA. At 10 ppm, 8 buds sprouted out of
8 buds, whereas at 20 ppm the figures were 4 out of 7 buds. Leaf initiation showed a better response at
the lower concentration than at the higher one, and a similar trend was also shown for inflorescence (Table
4).
Growth means an irreversible increase in the weight, area, or length of a plant or a particular tissue
or organ of a plant, while development denotes the changing pattern of organization as growth progresses.
Control over plant growth by the regulated exogenous supply of chemical substances may occur in dif-
ferent ways. It has become clear that total control of plants is vested not in a single hormonal type; rather,
control is shared by a group of several specifically defined auxins, gibberellins, ethylene, and certain nat-
urally occurring inhibitors such as phenols and abscisic acid. Thus, the plant growth regulators provide a
very helpful tool for controlling physiological processes in plants.
NAA was found to be better than IAA in rooting by Jauhari and Rehman [53] in cuttings of sweet
lime. It responded favorably on induction of roots in stem cuttings of many plants [69]. In the present
study IAA was found to be more effective than NAA.
Stem cuttings of Ipomoea pes-capraeand species of Morusshowed a large number of roots and buds
in the higher concentration but with maximum suppression of growth, whereas lower concentrations re-
sulted in only improvement in the growth of roots [70]. In our investigation also, the higher values were
observed with lower concentrations of the growth regulators.
Under favorable environmental conditions, during the period of root development, a callus tissue de-
velops at the basal end of a cutting: an irregular mass of parenchyma cells in various stages of lignifica-
tion. Callus growth arises from cells and adjacent phloem, although various cortical and medullar cells


138 SEN AND RAJPUT

TABLE 3 Effect of Different Concentrations of IAA and NAA on Bud Sprouting (BS), Initiation of Leaves
(L), and Number of Inflorescences (I) on Stem Cuttings of Morusspp. (Cultivated Var.) from Chopasni in
Growth Room (1993)


Total
Concentration buds on Dec. 12 Dec. 21 Dec. 30 Jan. 10
(ppm) cuttings BS L I BS L I BS L I BS L I


IAA
10 5 2 32 46 9 5811
1 1 11 12 1 12 1
20 7 2 33 46 3 48 6
11 1 121112
NAA
10 5 2 353 58 7 69 9
11 121 22123
20 7 2 331 46 4 58 5
22 111121 11
Control 4 1 2 2 1 3
11111

Free download pdf