Spikes of gladiolus are harvested when the first 5-6 flower buds show the colour and the first flower bud is ready to open the next day. Poor opening of flower buds was observed in some varieties when theywere harvested at very tight bud stage. Harvesting at bud stage eases transport of spikes without damage to buds. While harvesting spikes, at least four leaves should be retained on the plant to ensure proper development of corms and cormels. Spikes should be harvested with the help of sharp knife or secateur during cool hours of the day to avoid exposure of spikes to hot conditions which accelerates water loss and depletion of stored food due to more respiration.
The period of harvesting is different in different varieties and in general it varied from 10 to 15 days. Staggered planting with a gap of 10-15 days and planting of different grade corms of a single variety extend the flowering period. Care should be taken not to crush the stalk of spike at the time of harvesting because he crushed portion releases exudates whicpromote microbial growth in vase solution. If there is any delay in delivery, spikes should be placed in buckets containing water till they are sent to markets. Spikes can be bundled in units of 10 or 12, wrapped with news paper and loosely tied with rubber band to avoid the bruising.
They must be carried in vertical position to prevent geotrop.ic bending which is quite common in gladiolus. Pinching of topmost 3 or 4 flower buds reduces stalk curvature and also helps in proper opening of upper flower buds. Perforated card board boxeshaving 1.2 m length, 60cm width and 30cm height are convenient for safe handling of spikes to destination. Give a slant cut at bottom of the stalk and keep spikes immediately in buckets containing water. Spikes lose lot of water during transit and sometimes show the symptoms of wilting. On reaching the destination, they can be immediately kept in warm water which helps in reconditioning or rehydration of facilitates opening of flower buds. Based on the spike length and number of flower buds/spike, spikes are grouped into four grades
Vase Life of Spikes
Shelf life of gladiolus is mainly influenced by cultivar, cultural practices, harvesting stage, weather conditions and vase solution. In general, spikes kept in plain water last for 9-11 days under room temperature. Flower buds in the spike open from bottom to top. Varieties have definite pattern of flower bud opening in gladiolus, 1 or 2 buds open daily and each floret lasts for 2 or 3 days. In most of the varieties only a single bud opens in first 1 or 2 days and then two buds for 3 or 4 days and finally a single bud for 2 or 3 days. Normally, all the flower buds open in most ofthe varieties provided when the spikes are harvested at the right stage. Life of the first floret is most important in gladiolus and mostly, it lasts for 2 days in vase and 3 days on the plant in the field.
It has been found that organic manures improve shelf life of spikes for one or two days more as compared to chemical fertilizers. Care should be taken to change water daily or at least every alternate day, clean the container and cut stalk to enhance the vase life. Also, remove the faded flowers regularly to avoid the ugly appearance.Normally, two types of preservatives i.e., food providers and biocides are used for enhancing the shelf life of cut flowers. Sugar provides food to spike and keeps stalk in turbid condition whereas biocide checks microbial growth at the cut surface and in vase solution.
Sucrose as food source and chemicals like citric acid, 8-hydroxyquinoline sulphate,(8- HQ S), 8-hydroxyquinoline ci trate(8 -HQC), aluminium sulphate, silver thiosulphate and sodium hypochlorite as biocides are commonly used in gladiolus. So, the preservative solution used for gladiolus should contain both sugar and biocide. Of the vase solutions, sucrose (4%) + 8-HQC (250ppm) has been found as the best at improving the post harvest life and quality of gladiolus spikes. Shelf life of gladiolus spikes during winter months is slightly more as compared to other seasons. Geotropic bending of spikes: The tips of gladiolus spikes have the tendency to curve or bend down against the gravity if they are placed horizontally in transport.
Bending happens due to lateral downward movement of auxin (IAA) and its accumulation on the lower portion of the spike. IAA causes asymmetrical elongation of cells in the region and thereby causing the upward bending of spike tips. In some varieties, bent portion hangs down which in turn affects the vase life by restricting an upward movement of water. This is a common post harvest problem in gladiolus and some times it reduces marketable value considerably. The point of bending in spike varied from variety to variety and it is not uniform even within a variety. Pinching of
topmost 3 or 4 buds and keeping of spikes in vertical position during transport and storage container bending.
Lifting of corms and cormels and post harvest handling
Corms and cormels become matured when retained leaves on the plant starts yellowing. The time gap between harvesting of spikes and corms- varied from 6 to 8 weeks. Harvesting of corms should be done at the right satge of maturity for obtaining quality planting material. Premature harvesting sometimes leads to loss of viability of corms. However, delayed harvesting of corms produces lengthy spikes and more number of florets/spike. Harvesting can be done manually using pick axe or spade.
If the soil is hard, a light irrigation is to be given to facilitate the easy lifting of corms. Care should be taken to prevent damage to corms at the time of lifting and dressing and damaged corms must be treated with fungicides to avoid the fungal infection.Immediately after lifting, separate old mother corm and cormels from new corm. A delay in separation of old mother corms makes it difficult as they become dry and hard and finally injure the new corms.Adhered soil and leafy portion of new corms should also be removed. Infected corms and cormels can be discarded at the time of dressing. Handle the varieties separately to maintain the identity. Keep dressed corms and cormels under shade for drying in free ventilated place for a month for proper curing.
Then store them keeping in trays or net type bags under aerated conditions. Do not store them under air tight corms. There should be a provision for free passage of air through storage structures to avoid the fungal infection and keep them healthy. Drying of corms under the sun should be avoided as corms become spongy and will not be useful Owing to high humidity and continuous rain during rainy season, storage of corms has become a major problem in Goa. Corms can be dried under fan for a month and stored under room conditions.
If they are kept open there are chances for rotting of corms due to more humidity. Otherwise corms can be stored in cold rooms at 4- 7°c for three months. A study on the storage of corms was taken up during June – December 2003 to find out suitable and low cost method by using locally availableresources. Corms were stored in four types of environment 1. Corms were kept in plastic basins covered with dry soil, sand, saw dust and coir dust up to 5cm height. 2. Steel cupboard/air tight place. 3. Cold storage. 4. Plastic trays at room condition. Corms stored in steel cupboard got spoiled by storage fungi within 45 days whereas corms stored in refrigerator at 0° C become soft and lost viability.
Air tight conditions might have favoured the infection of corms. Cold injury at 0°C damaged the corms. However, corms stored at 4°C were good even after 184 days and germinated without any problem in the field. Scaled corms kept in room condition sprouted after 143 days but de scaled ones at the same condition sprouted after 76 days. Descaling (removal of scales) of corms reduces the dormancy period by 50% as compared to scaled corms. Spread a layer (5cm) of soil or sand in storage room, place dry corms and cormels in 2 or 3 layers and cover again with soil or sand up to 5 cm thick. This practice is cost effective, easy, convenient and above all ensures safe storage of corms without spoilage during rainy season.
Effect of different environments on storage of gladiolus corms
Storage life (days)/days
Spike and corm yield in gladiolus depend on cultivar, corm size, plant density, season, location and crop management. In general, yield in gladiolus is measured in terms of spikes and corms produced/ unit area. There is a positive relation between the size of corm and plant density and yield. The higher the plant density and corm grade, the more is the spike and corm yield. Marketable yield in gladiolus may be taken 10-15 % lesser than total yield. Normally small size corms produce one spike and one corm. Marketable spike yield is about 1.15 lakhs/ha whereas corm yield is nearly 1.25 lakhs when the plant population is 1.25 lakhs/ha.
- Central Coastal Agricultural Research Institute, Ela, Old Goa, Goa