K. SURESH KUMAR*, R. CHANDRA SHEKAR AND D. RAJANI
Subject Matter Specialist (Hort), KVK, Madanapuram, PJTSAU, Telangana
Effect of chemicals on corm and cormel production in gladiolus cvs. American Beauty and White Prosperity were studied in herbal garden at College of Horticulture, Rajendranagar, Hyderabad. The chemicals, Potassium nitrate (KNO3) at 0.5, 1.0 and 1.5 per cent, Salicylic acid (SA) at 50, 100 and 150 ppm, Propyl gallate (PG) at 0.5, 1.0 and 1.5 per cent were used on two cultivars. The corms were dipped in the solutions for a period of 10 hours before planting. Cultivar American beauty treated with Potassium nitrate at 1.5 per cent recorded highest number of replacement corms per corm (1.45), however with Salicylic acid at 150 ppm it recorded maximum number of cormels per corm (4.72). Among the chemical treatments, Salicylic acid at 150 ppm recorded maximum corm size (4.41 cm), corm weight (21.56 g), cormel weight per corm (6.59 g) and highest propagation co-efficient (184.72) with cv. White Prosperity followed by cv. American Beauty.
American Beauty, White Prosperity, Potassium nitrate (KNO3), Salicylic acid (SA) and Propyl gallate (PG)
Gladiolus (Gladiolus grandiflorus L.) is a bulbous cut flower of beauty and perfection. It is popularly known as ‘Queen of the bulbous flowers’ because of attractive spikes, having florets of different colours with long keeping quality. Gladiolus is very popular for its wide open, good texture, impressive coloured spikes which are of great demand in both domestic and international market. It is commercially propagated by corms. Poor multiplication rate and presence of corm dormancy for 3 to 4 months restricts their immediate use in the following season, resulting in high cost of corms which is often higher than the sale price of flower spike produced by the corm. The profitability of gladiolus flower spike production and export is closely linked to the cost of corms. Effective chemical treatments are to be standardized for this purpose irrespective of the cultivar, location and environment (Kumar and Raju, 2007). Synthetic growth regulating chemicals were reported to be very effective in manipulating the growth, flowering, corm and cormel production in gladiolus. Favourable effect of chemicals on sprouting, growth, flowering, corm and cormel multiplication in gladiolus has been reported by Roy Choudary et al. (1985).
The present study on the effect of chemicals on corm and cormel production in gladiolus cvs. American Beauty and White Prosperity was studied in herbal garden at College of Horticulture, Rajendranagar, Hyderabad. The chemical treatments, Potassium nitrate (KNO3) at 0.5, 1.0 and 1.5 per cent, Salicylic acid (SA) at 50, 100 and 150 ppm, Propyl gallate (PG) at 0.5, 1.0 and 1.5 per cent were treated on two cultivars. The corms scales were removed before dipping in the solutions for a period of 10 hours before planting. The treatments were replicated thrice in randomized block design with factorial concept. The data was analyzed using computer software programmed by the method of variance outlined by Panse and Sukhatme (1985). Propagation co-efficient (%) is defined as the ratio of the total weight of corm(s) and cormels produced and the weight of corm planted and multiplied by 100 to express in percentage (Rajivkumar et al., 2002).
Results obtained from the present study indicated that, the two cultivars differed significantly in respect of number, size and weight of corms and cormels produced per corm due to chemical treatments. Cv. American Beauty recorded maximum number of replacement corms
(1.13) and number of cormels per corm (3.87) compared to cv. White Prosperity (Table 1 and 2). The variation in production of number of replacement corms and cormels per corm might be due to variation in number of buds sprouted per corm, which might have been governed by the presence of number of active buds in the corms. Variation in cultivars on individual gladiolus corm characteristics was earlier reported by several workers (Prasad et al., 2002; Uma devi, 2002 and Kumar et al., 2007).
Number of replacement corms and cormels per corm in gladiolus cultivars differed significantly due to chemical treatments. Potassium nitrate in all the concentrations recorded maximum number of replacement corms followed by salicylic acid. The chemical treatment Potassium nitrate at 1.5 per cent recorded highest number of replacement corms (1.32) (Table 1) where as Salicylic acid at 150 ppm recorded maximum number of cormels per corm (4.63) (Table 2). Lowest number of replacement corms per corm (0.81) and cormels per corm (3.39) was recorded with Propyl gallate at 1.5 per cent. Potassium nitrate and salicylic acid increased the number of corms and cormels produced per corm (Table 1 & 2) significantly over control. In gladiolus besides photosynthesizing leaves, the corms used for planting also serve as source of reserve food in the early stages of sprouting and establishment of developing plant. Likewise, it has two competitive sinks, inflorescence or flower spike and developing corm/cormels and application of Potassium nitrate and salicylic acid increased the sink activity of both. Increase in corm and cormel production by Potassium nitrate and Salicylic acid treatments may be attributed to their ability to alter the hormonal balance in the corms and cormels resulting in increased ratio of promoters versus inhibitors. This alteration in hormonal balance maintains sink activity of corms and cormels which resulted in production of more number of replacement corms and cormels per corm. Similar results were also reported by Kumar (2005) in gladiolus cvs. Jyotsna and Shabnum.
Cultivar White Prosperity recorded significantly maximum corm diameter and weight over cv. American Beauty. The replacement corm size (3.83 cm), weight (19.00 g) and cormels weight per corm (4.35 g) was significantly high with the cultivar White Prosperity over cv. American beauty (Table 1 and 2).
The chemical treatments were also effective in improving the individual corm characteristics. Salicylic acid
at 150 ppm recorded maximum replacement corm size (4.35 cm), weight (21.44 g) and weight of cormels per corm (6.43 g). Lowest replacement corm size (3.31 cm) was observed with Potassium nitrate at 0.5 per cent, however Propyl gallate at 1.5 % recorded lowest replacement corm weight (17.09 g) and cormels weight per corm (2.96 g). Potassium nitrate and Salicylic acid at higher concentrations recorded maximum vegetative growth over the lower concentrations studied. Whereas Propyl gallate at lower concentrations recorded maximum vegetative growth over higher concentrations studied. Potassium nitrate and Salicylic acid stimulates alternate oxidase and in turn promotes alternate respiration (Chen and Klersig, 1991) thereby they improved the vegetative growth. These treatments were consistent and equally effective in increasing the leaf area almost during the entire crop growth period. The increase in leaf area and increased assimilate synthesis, might have contributed to increased number, size and weight of replacement corms and cormels by these treatments. Propyl gallate, an inhibitor of alternate respiration and ethylene biosynthesis (Krishnamoorthy, 1993) recorded in maximum number of days for sprouting of corms and lowest sprouting percentage resulted in low vegetative growth. Due to inhibitory action of Propyl gallate, higher concentrations might have suppressed plant growth and effects number, size and weight of replacement corms and cormels. Similar results were also reported by Kumar (2005) in gladiolus cvs. Jyotsna and Shabnum.
There was no significant difference between the cultivars on propagation co-efficient. Salicylic acid at 150 ppm recorded maximum propagation co-efficient (182.22) whereas Propyl gallate at 1.5 per cent recorded minimum propagation co-efficient (93.45).