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SREEDHAR DEVARAKONDA*, NAGARAJU RACHAKUNTA AND Y. SHARATH KUMAR REDDY, AND Y. CHANDRA SEKHAR
Scientist (Hort), Horticulture Research Station, Dr. Y.S.R Horticultural University, Anantharajupeta, Railway Kodur, Kadapa Dist., Andhra Pradesh, India
Gladiolus (Gladiolus grandiflorus L.) is one of the most widely cultivated, economically important and common flowering plants worldwide including India. However, the flower yield is quite low when grown under agro-climatic conditions of Rayalaseema zone of Andhra Pradesh. A field experiment was conducted at Horticulture Research Station, Anantharajupeta. Railway Kodur, Kadapa district Andhra Pradesh, India during 2016-2017 to investigate the effect of micronutrients (Zn, B and Fe) on growth, flower yield and quality of gladiolus cv. Arka Amar. Eight treatments comprised of either each micronutrient alone or a combination of Zn, B and Fe were applied. Corms were planted within the first week of November 2016, Row to row and plant to plant spacing was maintained 30 x 20 cm, respectively. Fifteen corms were planted in each treatment with three replicates. The first spray was applied at 3-leaf while the second at 6-leaf stage. Application of the micronutrients significantly increased plant height, number of leaves per plant, spike length, spike girth, rachies length, florets per spike, number of cormels per plant and flower vase-life. Among the micronutrient treatments, the treatment containing FeSO4.7H2O(0.2%), H3BO3 (0.2%) and ZnSO4.7H2O (0.5%) per-formed the best for all the parameters except for number of corms per plant and diameter of floret which was not affected significantly by the foliar application of the micronutrients.
Flowers symbolize purity, peace, beauty, love and passion. For Indians, especially, those who are religious minded flowers have a great significance. In our society, none of the social functions will be completed without the use of flowers. Regarding flowers, gladiolus (Gladiolus grandiflorus L.) is one of the most cultivated, economically important and common flowering plants world-wide including India and is among the elite cut flowers due to different shapes, hues and prolonged vase life (Bose et al., 2003). Gladiolus, a member of family Iridaceae and sub-family Ixidaceae, originated from South Africa and is a prominent bulbous cut flower plant. The genus Gladiolus contains 180 species with more than 10,000 cultivars (Sinha and Roy, 2002). It is of great economic value as a cut flower and flower for decoration. It ranks second after tulip among the bulbous flowers in India and has occupied fourth position in the international trade of cut flowers. The fascinating spike bears a large number of florets with varying sizes and forms with smooth ruffle of deeply crinkled sepals.
The commercial growers are growing gladiolus in different zones of the country especially in Uttar Pradesh, West Bengal, Odisha, Haryana, Maharastra, Karnataka and Andhra Pradesh to fulfill the local consumption demand; however the production and flower quality are still too low to meet the international standards. Its cultivation is gaining popularity among the farmers in different areas of south India specially in Andhra Pradesh and has recently been seen as a lucrative enterprise due to increased awareness and recognition of the high return on its investments. The suitable agro-climatic conditions of the country clearly indicate that a wide range of ornamental crops can be grown, which can improve the economic status of the growers. However, quality production is in dire need of standard agricultural practices, including nutrient management. Chemical fertilizers play a vital role in growth, quality of flowers, corm and cormel production. Gladiolus requires adequate amounts of chemical fertilizers in their balanced proportions for ensuring maximum flower production. Being involved in the physiology of plants, micronutrients well contribute to the growth and yield of the plants. Within different areas,
productivity of crops is being adversely affected by micronutrient deficiencies, the deficiency having been markedly increased due to intensive cropping, loss of top soil by erosion, loss by leaching, liming of soil and as well, a decreased in the availability and use of farmyard manure (Fageria et al., 2002).
The micronutrients play crucial and vital role in gladiolus production as well as major nutrients in growth and development. The effective study on micronutrients under this aspect zinc, iron is necessary in every stage of plant growth particularly in gladiolus as like in other plants. To determine the commercial value on corm production parameters, the micronutrients contributes most important role on various metabolism and synthesis process in plants. Information regarding nutritional requirements and appropriate soil management practices are lacking for gladiolus cultivation in India. So the growers lack enough information on these elements and are not familiar with their prominent role in increasing yield and producing high quality cut flowers, causing soils deprived of micronutrients which in turn can hamper plants to produce their optimum size of spike, corms and cormels for flower cultivation. There are evidences that iron deficiency impairs many plant physiological processes because it is involved in chlorophyll and protein synthesis and in root tip meristem growth. Tagliavini and Rombola (2001) illustrated that iron deficiency (chlorosis) is a common disorder which affects plants grown on soils of high pHs. This may lead to serious yield and quality losses, demanding the implementation of suitable plant iron-deficiency correction strategies. Iron application through foliar spray is a common practice to cure iron-deficiency (Mortvedt, 1991). Boron plays a vital role as stabilizer of cell wall pectic network (Dordas & Brown, 2005). It promotes the stability and rigidity of cell wall structure and therefore, supports the shape and strength of the plant cell (Brown et al., 2002). Furthermore, boron is possibly involved in the integrity of the plasma membrane (Brown et al., 2002; Cara et al., 2002; Dordas & Brown, 2005). Zinc is an essential micronutrient necessary for sugar regulation and assorted enzymatic activity associated with plant growth (Khosa et al., 2011). The plants treated with Zn shows increase plant height in gladiolus due to its role in synthesis of tryptophan, which is a precursor of auxin (IAA) and is essential in nitrogen metabolism, which stimulates growth. (Rahul and Ashok, 2014) Zinc plays an important role in protein and starch syntheses, and therefore, a low zinc concentration induces accumulation of amino acids and
reducing sugars in plant tissue (Graham and McDonald, 2001). Amir et al. (2008) observed that rose cultivars’ flower vase life had been extended when plants treated with Zn. Foliar applications of micronutrients are most completely available to the plant, because they are not either fixed or diluted in some large volumes of soil (Baloch et al., 2008). Mukesh et al. (2001) investigated the effect of foliar application of Zn, Cu, and Fe at 0, 250, 500 and 1,000 ppm on the yield and quality of gladiolus. Plants treated with micronutrients exhibited better results as compared with the control. However, foliar application of Fe, Cu, and Zn at 1,000 ppm showed best results with respect to growth, flowering and other yield parameters. In gladiolus, spike length, number of florets, weight of spike and size of florets were significantly increased with 0.2% FeSO4+0.2% ZnSO4 application (Kumar and Arora, 2000).
At present, there is an urgent need to standardize agro techniques which are most suitable for local climatic and edaphic conditions. But the paramount problem, the farmers are facing is judicial use of chemical fertilizers. Keeping in view the significance of gladiolus in global cut flower trade, a field experiment was executed to find out the response of Gladiolus grandifloras cultivars to foliar application of various micronutrients for enhancing yield and improving quality and corm indices. The objective of the present study was to investigate the effect of micronutrients (Zn, B and Fe) on growth, flowering and vase life of an gladiolus cultivar ‘Arka Amar’ under agro-climatic conditions of Rayalaseema Zone.
The experiment on “Effect of Zn, B and Fe on growth, flowering and vase life of gladiolus was conducted at Horticultural Research Station, Anantharajupet, Railway kodur, Kadapa district of Andhra Pradesh, India.. The corms of ‘Arka Amar’ variety of gladiolus was procured from Indian Institute of Horticultural Research, Bangalore. The experimental field had loamy soil. Manure and fertilizers were given according to recommendation. The experiment was laid out in Randomized Block Design with three replications and 8 treatments. The treatments were randomized for getting equal chance in respect of fertility. Row to row and plant to plant spacing was maintained 30 x 20 cm, respectively. Irrigation, weeding, hoeing, earthing up and staking operations were completed according to needs. The treatments contained 0.5% solution of zinc (Zn), 0.2% solution of each of iron (Fe), boron (B) salts
applied in various combinations. Fe was applied as ferrous sulphate (FeSO4.7H2O), B as boric acid (H3BO3) and Zn as zinc sulphate (ZnSO4.7H2O). Control plants were sprayed with plain water. The micronutrients were sprayed on the plants. A detail of the treatments is presented in Table 1.
The first spray was applied at 3-leaf while the second at 6-leaf stage. The ground of each bed was covered with polythene sheet. For an estimation of the vase life, flower stalks were harvested when most of the lower florets had started showing color. Two lowest leaves were left intact with the plant for better development of corms. Spikes were immediately kept in buckets containing distilled water and brought to the laboratory. The leaves of the stem were removed and the stems kept individually in glass vases containing 200 ml of distilled water. Every two days, vase water was replaced with fresh distilled water and a lower 2.5 cm of stem was also cut for better water uptake. Five spikes per treatment in each of the replications were taken for vase life evaluation. Spikes were considered dead when more than 50 per cent of the florets wilted, dried or faded away. The number of corms and cormels were recorded at the time of lifting the corm.
Statistical analysis of the data on plant height revealed significant differences among the micronutrients treatments. The plants sprayed with all the three micronutrients (T7) resulted in maximum plant height (59.33 cm) followed by T5 i.e Zn and Fe (55.33 cm). These findings indicated that all the three micronutrients (Zn, B and Fe) applied as foliar spray were needed for
the plant’s growth and contributed towards better growth of gladiolus in terms of plant height. Kumar and Arora (2000) have already reported increased plant height with foliar application of 0.2% FeSO4, when gladiolus cv. White prosperity plants were sprayed at 3- and 6-leaf stages with FeSO4, MnSO4 and ZnSO4 at 0.2 and 0.4% levels of each. Similarly, increased vegetative growth has also been reported in gladiolus grown on partially reclaimed sodic soils by foliar application of Zn+Cu, each at 0.2% applied twice (Katiyar et al., 2005). Lahijie (2012) too, found that an application of FeSO4 (0.5 or 1%) and ZnSO4 (0.5 or 1%) either singly or in combination, applied at 2- and 6-leaf stages, significantly increased height of gladiolus cv. Oscar plants.
Regarding the number of leaves, significant variations were observed. More number of leaves (9.20) was observed with T7 i.e when all the three micronutrients were applied together. T7 is statistically at par with T4, T5, T6 i.e when the micronutrients applied in combinations of two. Leaf number is considered as an important factor in growth, responsible for photosynthesis and ultimately affecting the flower yield and quality. These results are in support of Kumar and Arora (2000) and Halder, et al. (2007a) findings, who observed increase in number of leaves as a result of foliar application of different micro-nutrients on gladiolus. Kumar and Arora (2000) sprayed gladiolus cv. White prosperity with FeSO4, MnSO4 and ZnSO4 at 0.2 and 0.4% levels of each. The results revealed the number of leaves increased when 0.2% FeSO4 was applied at 3- and 6-leaf stages. Foliar application of FeSO4 (0.5 or 1%) and ZnSO4 (0.5 or 1%) alone or in combination and at 2- and 6-leaf stages, significantly increased number of leaves per plants in gladiolus (Lahijie, 2012).
Spike length, spike girth and rachis length
Spike length, spike girth, Rachis length were significantly influenced by the micronutrients’ treatments. Combined application of all the three micronutrients (T7) significantly improved spike length (106.17 cm), spike girth (3.91 cm) and Rachis length (51.83 cm). Length of spike is an important determining factor counted on for good economic return. Kumar and Arora (2000) stated that spike length, number of florets, weight of spike and size of florets significantly increased with 0.2% FeSO4+0.2% ZnSO4 foliar application. Similarly, Lahijie (2012) also reported significant increase in length of spikes of gladiolus
cv. Oscar, when FeSO4 (0.5 or 1%) and ZnSO4 (0.5 or 1%) were applied either singly or in combination. Katiyar et al. (2005) found that foliar spray of Zn (0.2%) and Cu (0.2%) applied twice increased the length of spikes in gladiolus grown in partially reclaimed sodic soils.
Number of florets per spike
Maximum number of florets per spike (16.17) was noted when all the three micronutrients were applied in combination (T7) and this number was significantly higher than that for all the other micronutrients treatments. It was shown in the present study that with an increase in the spike length, the number of florets per spike was also increased. These results also confirmed the findings of Kumar and Arora (2000), who observed that foliar application of different micronutrients significantly influenced the number of florets per spike. The number of florets per spike was also significantly increased in gladiolus (as a result of the application of FeSO4 and ZnSO4) either singly or in combination (Lahijie, 2012). Katiyar et al. (2005) also found that foliar application of Zn (0.2%) and Cu (0.2%) to gladiolus plants, grown in partially reclaimed sodic soils, enhanced such floral characteristics as the number of florets per spike.
Analysis of variance of the data on diameter of floret depicted non-significant differences for treatments, indicating that the parameter was not affected by the micronutrients treatments applied.
Analysis of variance of the data on number of corms produced per plant depicted non-significant differences for treatments, indicating that the parameter was not affected by the micronutrients treatments applied. In the present study, the number of corms produced per plant varied from 1.22 to 1.66; hence neither a single foliar application of micronutrients nor in combination have any influence on corm number per plant.
The foliar application of Zn, B and Fe significantly increased the number of cormels per plant (Table 2). Highest number of cormels per plant (19.44) was observed in T7. These findings are in supports of and Chen et al. (1982) and Haldar et al. (2007 b) in gladiolus.
Significant differences among treatments was observed regarding vase-life of spikes. Foliar application of all the three micronutrients (T7) resulted in longest vase life of spikes (8.66 days) followed by the combined application of FeSO4 + ZnSO4 (T5). The shortest vase life was observed for the spikes harvested from plants not treated with any micronutrients (T0) and significantly differing from all the other treatments. All the other treatments stood in the middle. Pratap et al. (2008) studied the effect of pre-harvest micro-nutrient foliar sprays on post-harvest vase life of gladiolus cv. Traderhorn using post-harvest vase chemicals. Pre-harvest foliar application of FeSO4 0.75 or 1% along with ZnSO4 0.5% significantly extended the vase life of the flowers. The results of the present study also confirmed the findings of Amir et al. (2008) who observed that application of Zn to rose cultivars resulted in extended vase life of the flowers.