The name gladiolus is well known among the cut flowers and ranked 3rd to 4th in the international trade of cut flowers. The beauty of spikes is famous among all of the flower lovers.
The name gladiolus has been derived from a Latin word gladiolus meaning sword as the leaf of gladiolus resembles a sword. Gladiolus has various names from the past as ancient Greeks called it xiphion (Iris).
In Europe it is known by a local name corn flag because a specie of gladiolus namely gladiolus illyricus is found as wild weed in corn fields. There is another name water fall gladiolus given to gladiolus primilus as these occur wild in Victoria falls in Africa.
About 30,000 cultivars are known and thousands added every year. The commercial life of a variety is around 10-15 years. The list of most important varieties which are cultivated for commercial purpose by the farmers include Melody, Snow Princes, Sylvia, American Beauty, Angelia, Blue Sky, Friendship, Suchatra, Mayur, Happy End, Hunting Song, Jester, Rose Supreme, White Prosperity, Nova Lux, Trade Horn, Oscar and Peter pears.
The propagation of gladiolus is commercially done by using corms or cormels. The corms can produce per year one to three such corms which can be planted for getting a quality flower spike. However, besides corms it produces smaller cormels which are sown and not allowed flowering so these can give birth to such corms which will provide such flowers which has a market value. The corms are grades as per the diameter; i.e., large, medium and small. The classification of corms includes the corm sizes.
Cormels are produced by corm but it should not be allowed to flower before the time it attains a size by which it develops a potential to give rise to a big size spike.
Generally, there are various factors responsible for achieving proper size of corm from cormels which include proper planting method (Shallow planting in loose soil which helps it to proliferate easily), maintenance of nutrition, cultural practices etc.
Under sandy loam conditions cormels are planted 15-20 cm row to row distance, 3-5 cm apart and around 3.5 cm deep. Mid-September is considered an ideal time for planting cormels in north Indian plains while as for hills it is February to March.
The soaking of cormels in hot water for 24 hours has two advantages; it provides an opportunity to remove dead cormels and second it aids germination. After soaking, the bagged cormels are exposed to the sun which helps in accelerating the germination process.
Role of growth substances
Treatment of corms with ethrel @ 2000 to 4000 ppm for half hour removes dominance and helps in formation of more cormels.
Dipping of cormel or corms in a solution containing 50-100 ppm GA aids in accelerating germination.
The propagation through seeds is restricted for breeders to evolve new varieties.
It provides disease free planting material. The micropropagation technique is performed through axillary buds, corm or spike axes or stem and floral parts. The propagation is done on modified MS media.
Well drained, well aerated soil with neutral pH, light in texture preferably sandy loam soil is excellent for gladiolus cultivation.
Preparation of soil
Soil before planting is ploughed thoroughly and exposed to sun to kill harmful soil microorganisms. The soil is exposed during May-June. Covering soil with black polythene is advised. After this the field is ploughed properly with incorporation of 10 tones well rotten FYM per hectare followed by addition of 40 kg phosphorus and 40 kg of potassium per acre.
The plant to plant and row to row distance should be kept 30cm x 20cm. The depth of planting should be kept at 7cm. Field for cultivation of gladiolus should not be regularly used. It should be changed every year. The cultivation may be done after a 3 to 4 years gap in any field.
The irrigation scheduling is fixed on the basis of prevailing climatic conditions. The irrigation scheduling depends upon the season and soil type. Under heavy soils less irrigation is given compared to light soils.
Besides this, the stage of growth determines the quantity of water required. During the peak vegetative stage, if there is shortage of water, the growth is influenced badly which in turn influences flowering.
In general, the irrigation is given at a weekly interval during summer and at a 15 days interval during winter.
Basal N 60 kg/ha, P 150 kg/ha, K 150 kg/ha. Top dressing N alone is given @ 30 kg/ha during 4 leaf stage as foliar spray and 30 kg/ha during bud stage as soil application.
Integrated weed control including pre-emergence herbicide use apart with hand weeding are effective means for weed control. Hoeing should be done to ensure proper aerated condition of the soil. Care should be taken not to damage plants or corm as it can carry fungal or insect disease.
For distant market spikes are harvested when the lower or basal floret shows colour while for local markets the spike is harvested when the basal floret is fully opened.
Pre-cooling is immediately done to remove field heat and minimize respiration rate. Pulsing should be done to make the spike possible conditions for opening. Pulsing solution recommended for gladiolus is 20% sucrose apart with 200 ppm 8HQC. Spikes should be kept in this solution for 24 hrs.
Yield: 70,000 to 75,000 spikes/acre.
Storage temperature: 10C to 20C.
Cardboard boxes measuring 100cm x 25cm x 10cm in LBH are recommended for packaging of gladiolus.
Harvesting of Corms
After around 6-8 weeks after harvesting of spikes, corms or cormels can be lifted. The maturity index of corms is the yellowing of leaves after 2-3 weeks prior to pitting. The shade drying of the corms is done followed by removal of leaves and treatment with fungicides preferably Bavistin @ 0.2% for half an hour.
Storage of Corms
The packaged corms are stored at cool temperature and high humidity. The recommended temperature for storage is 30C with relative humidity of 90%.
Neck rot: The causal organism responsible for neck rot is Stromatinia gladioli or Selerotinia gladioli. The neck rot or root rot can be recognized by rotting (Watery) of leaves apart with stem at soil level. The leaves turn brown from top towards bottom.
• Cold water treatment of corms for 24 hours followed by hot water treatment around 500C for 30 minute.
• Use Bavistin @ 0.2%.
• Corm treatment with dicloran.
• Maintain optimum moisture and environmental conditions.
Fusarium wilt: The fungus responsible for spreading and causing this disease is Fusarium oxysporum f.sp. gladioli. The characteristic symptoms are yellowing of older leaves, dark green colour of spikes and floral parts followed by wilting. Brown spots or streaks are seen when dissection of corms is done.
• Healthy and disease-free propagation material.
• Maintain optimum nutrient level in the field.
• Soil sterilization before planting.
• Crop rotation and the gladiolus to be grown in a specific field after three to four years.
• Treat corms & cormels with a solution of captaf heated at around 400C for 30 minutes.
Leaf spot: The causal organism of this disease is Curvularia trifolii f. sp. Gladioli Parmela and Luttrell. The characteristic symptoms of this disease are; brown spots on petals and leaves. Besides this the nature of the disease being soil born, it attacks cormels and proceed to flowers under warm & humid climate. The infestation is more on young leaves and cormels. Plants in their young age may die without any specific symptom.
Control: Use mancozeb at 10 days interval.
Flower blight: The symptoms resemble in the initial stage with leaf spot followed by water-soaked patch formation on young flowers, calyx and on petals which with advance of the infestation turn brownish black. The severe infection led to flower bud rotting.
Control: The control measures are the same as for leaf spot.
Viral diseases: The viral disease vectors in gladiolus are aphids, nematodes & leaf hoppers. The characteristic symptoms are white streaks on leaves, petal streaking, flower distortion, rotting of corms which fail to germinate.
Control: Proper control of insects which transmit this disease.
Tip burn: The cause of tip burn is the high level of fluorides in the atmosphere. The fluorides are absorbed and get accumulated in the tip portion. The characteristic symptoms are discoloration of leaf tip followed by drying up.
Control: Spray Biltox 50wp (0.3%) up to control.
Aphids: The sucking nature of this insect led to discoloration and economic losses.
Control: Spray Malathion @ 0.2%.
Borer: These damage leaves, unopened florets, seed, capsule and seed by feeding on these parts.
Control: Spray Thiodan 35EC @ 0.5 to 0.8%.
Thrips: These damage foliage and flowers by causing silvering and whitish streaks. These affect florets as well.
• Spray parathion @ 0.04%.
• Cormel treatment with BHC prior to storage.
Nematodes: These attack the root system. It is prevalent under loose soils. These attack both corms & roots.
Control: Soil fumigation is an excellent measure to control nematode problems. Besides this, hot water treatment of corms helps in controlling nematode problems.