Preparation of land
Gladiolus requires good soil preparation for its better growth and yield. Land should be ploughed thoroughly at least a fortnight prior to planting of corms. Exposure of soil to the sun is required to kill weeds and insects. Ploughing, harrowing and leveling ofland can be done with an interval of7 days. Apply the recommended dose of manure prior to ploughing of soil. Open the furrows and ridges as per the spacing and make irrigation channels a day prior to the planting. Gladiolus does not need deep cultivation as it is a shallow rooted crop so the ploughing to a depth of30 em is sufficient.
In India, gladiolus production is seasonal and mostly grown during winter in plains andsummer in hills. It comes up well under varied climatic conditions of temperate, sub-tropical and tropical regions. It is grown throughout the year in places like Bangalore. Results of evaluation studies under agro-climatic conditions of Goa indicated that gladiolus cultivation is possible round the year since the weather prevailing in the state is moderate. Currently, gladiolus production in the state is just confined to winter season. There is a great scope to expand the crop to other seasons as there is a regular demand for flowers.
There are views that crop cannot come up well in the rainy season. Crop growth and yield have been found better in rainy season compared to summer grown crop. Staggered planting with a gap of 10-15 days interval can be taken up for regular supply of flowers to florists. Planting of different grade corms of the same variety and early, medium and late varieties together also extends flowering period.
Open furrows up to 15cm depth, plant corms in furrows and cover with soil to avoid an exposure to the sunlight. Care should be taken not to plant corms upside down.
Planting can be done in furrows in all seasons. However, planting on ridges is better for water logged or ill-drained areas because plants can not tolerate water stagnation. Normally corms are planted at 15-25cm apart in a row and rows are spaced at 30-45 cm apart. Accordingly, the density of planting varied from 1-1.5 lakh plants per hectare. There should be enough space between rows to facilitate intercultural operations.Among the various characters studied, only the plant height, leaf length, corm size and corm weight were found significant among the treatments (Table 5). Plant height and leaf length were more at closer spacing.
This may be due to the fact th~tpl~nts tend to grow vertically when they are crowded owing to shadowing effect of plants on one another. Maximum corm size and corm weight were recorded at wider spacing whereas the minimum at closer spacing. More competition for nutrients and space among the plants at closer spacings might be responsible for less corm size and weight. And also shadowing effect of plants with one another might have affected photosynthesis and ultimately, accumulation of dry matter in plants. The convenient and optimum spacing for Goa is 40 x 20/45×20 cm which can accommodate 1.251akh plants/ hectare.
Depth of planting is mostly dependant on the size of corms, soil type and season.There is a direct relation between the corm size and depth of planting. The higher the corm size the more is the depth of planting. Plantin depth must be more in light soils as compared to heavy soils. Optimum depth of planting for small, medium and large size corms is 5cm, 7cm and 10cm, respectively. In sandy soils corms can be planted 2:5 em more deeper in each grade. It is better to avoid very deep as well as very shallow planting.
Table 5. Effect of spacing on vegetative, flowering and corm characters of gladiolus cv.White Prosperity
There is a positive correlation between corm size and vegetative growth, flowering and corm production (Table 6). Relatively, improved growth and flowering and corm size and weight were observed in plants raised from large sized corms. This may be attributed to presence of more food reserves and hormones like gibberellic acid (GA) in big size corms.
The performance of cut corms obtained from Jumbo (6-7cm) size corms was found better in some of the characters like days to flowering, number of florets/spike and corm size as compared to grade No.3 corms. This may be attributed to bigger size of cut corm rather compared to whole corm of grade NO.3. Though plants raised from Jumbo grade corms had shown better performance in flowering parameters over other grades, it is suggested to use cut corms of the same since the shoot or corm production of Jumbo corms was just 1.17 per plant.
- Central Coastal Agricultural Research Institute, Ela, Old Goa, Goa