Gladiolus is a water loving plant and needs sufficient moisture in the soil till the harvesting of spikes. Flower bud initiation and spike elongation are the most critical stages in gladiolus. Moisture stress during these stages results in a considerable damage to growth and yield. Water requirement and frequency of irrigation depend on the soil type, weather conditions and stage of the crop. Lateritic soils need more number of irrigations compared to sandy loam soils. Irrigation is not required in rainy season unless there is a dry spell. In lateritic soils, irrigation should be given once in a week during winter and twice in a week during summer whereas in sandy loam soils once in a week during summer and once in a week or 10 days during winter.
Normally, irrigation can be cut down after the harvest of spikes and withheld completely once leaves start yellowing. If the soil is hard, a light irrigation may be given to facilitate the lifting of corms from the soil. Irrigate the crop once in 10 days when it is grown under partial shade of coconut gardens during summer season. It can tolerate high summer temperature and come up well if sufficient moisture is maintained in the soil during the crop period.So, the success of the crop in summer is mainly dependant on the irrigation.
Weeds compete with crops for water and nutrients and also host insect pests. Gladiolus is a shallow rooted crop which can easily succumb to weeds. If the weeding is delayed or neglected, weeds take over the crop and pose serious problem for humid conditions prevalent in the state encourage weed growth. Therefore, field must be kept weed free till the flowering/ harvesting of spikes and the frequency of weeding mainly depends on the intensity of weed growth.
Normally two or threeweedings with a gap of 20-30 days are required during the crop period. Weeding can be done either manually using kurphi/hand hoe or by using herbicides. If there is a labour problem, herbicides like glyphosate/ grammoxone @ 0.6 It/1000 sq.m. can be applied to the soil prior to the planting of corms. Application of herbicides can not be taken up in standing crop as they injure plants and cause abnormalities in growth.
Mulching helps in conservation of moisture and suppression of weeds during the crop period. This practice cuts down the expenditure and provides comfortable environment to plants. It is·a good option for water scarcity areas and when the crop is grown during summer months. Farmers can reduce the frequency of irrigation, weeding, save sizeable amount of money and get higher yield. It should be kept in mind that mulching can be done only after earthing up operation. Farmers are advised to use dry grass available in and around thefields or else freely available materials like coir dust. Effect of mulching depends on the type and depth of mulch. Mulching must be at least 7.5 cm thick so that it does not allow any weed growth.
Gladiolus responds well to externally applied organic manures and inorganic fertilizers. Application of chemical fertilizers should be as per the requirement which can be known only through analysis of soil. Nutrient requirement depends on the nature of soil, weather conditions and corm size. Judicious and balanced application of manures and fertilizers is most important and crucial practice in gladiolus production. Plants produced from large corms need lesser quantity offertilizers than plants from small size corms. Farm yard manure@ 3t/ 1000sq.m can be applied at the time ofland preparation.
Application of overdose of manures should be avoided as it tends to produce tall and slender spikes which may lead to lodging of plants. Growth and yield of gladiolus were found better when manure was applied in furrows rather than whole area. When the field is ready for planting, open the furrows to a depth of 15 cm, apply mixture of fertilizers and manure in furrows and mix them with soil. So, cattle manure/ FYM @ 2t/l000 sq.m can be applied in furrows along with fertilizers at the time of planting rather than applying prior to ploughing of the land.
It saves lot of manure and provides ideal environment to plants in the rhizosphere. This practice increases the spike length, number of florets/spike, corm weight, corm size and cormel production as compared to broadcasting. But care should be taken to use the well decomposed manure. A field experiment was carried out to find out the effect of various organic manures (Table 8) over growth and yield of gladiolus variety White Prosperity. Results revealed that significant variationwas noticed among the treatments for major yield attributes like spike length, rachis length and no of florets/spike.
The maximum spike length and highest number of florets/ spike were observed in goat and pig manure as compared to control. In addition to farm yard manure, farmers can use locally available pig manure, vermi compost, poultry and goat manure. NPK in the form of urea, single supe used. The quantity of fertilizers required for 1000 m2 is 25kg urea, 90kg single super phosphate (SSP) and 25kg muriate of potash (MOP). Full dose of phosphorus and potassium and l/3’d of nitrogen can be applied as a basal dose at the time of planting of corms. Remaining dose of nitrogen can be applied 30 days after planting of corms. In late varieties, it is better to apply nitrogen in three equal splitsbasal, 30 and 60 days after planting.
Cattle urine being rich in nutrients and growth hormones like auxins has been found as good substitute for chemical fertilizers (Table 9) in gladiolus. It enhances the plant height,spike length, number of florets/spike. Liquid manure prepared with water did not show manure prepared with cattle urine. Cattle urine lOO% fermented for a week can be applied twice (3-41t1sq.m) to the soil. First dose can be given at the time of planting and second dose after a month of planting. Significant improvement in corm size and corm weight was noticed with application of fertilizers.
- Central Coastal Agricultural Research Institute, Ela, Old Goa, Goa