National Botanic Gardens, Lucknow
Sixteen foliar sprays at fortnightly intervals comprising of three levels each of nitrogen (Urea) 0.80, 1.60 and 2.40 gm, phosphorus (Orthophosphoric acid) 0.20, 0.40 and 0.60 gm and two levels of potassium (Potassium citrate) 0.64 and 1.28 gm per plant in eighteen treatment combinations were applied directly onto the foliage of the tuberose plants besides control (Distilled water + wetting agent).
Increasing levels of nitrogen were found to increase the number and diameter of mature bulbs leading to the production of well developed clumps with more number of bulblets and formation of lengthy roots as compared to the control plants.
The response of application of phosphorus at the highest level (P3) was reflected in the significant increase in the number of mature bulbs and bulblets per clump and on the weight of the clump formed. The improvement in the diameter of mature bulbs formed though remained non-significant in the first year became significant in the subsequent year at the highest level of application. The length of roots formed was decreased with increasing levels of phosphorus.
The application of potassium at both the levels, however, did not significantly affect size and number of mature bulbs, bulblets and weight of the clumps formed. In the subsequent year, probably due to the residual effect there was significant improvement in the number of mature bulbs and bulblets and weight of the clump at both the levels of potassium application. The length of roots decreased with increasing levels of potassium.
N x P interaction for the number of bulblets per clump was proved to be significant during the year 1969–70 only. In the subsequent year, the response was more pronounced on all the characters under study which was attributed to the residual effect of foliar nutrition.
