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The project on ‘Flower bud forcing in humid tropic mangoes using dormancy breakers’ was taken up at Department of Pomology and Floriculture, College of Horticulture during March 2006 to April 2007.

The objective of the experiment was to study the effect of nitrogen compounds, viz., nitrates and their combinations with micronutrients and thiourea on stimulation of flowering in mango cultivars Muvandan and Priyor under the humid tropic situations of Kerala.

The treatments involved KNO3 at 1.00 per cent and 2.00 per cent levels, NH4NO3 at 0.50 per cent and 1.00 per cent, their combination with micronutrients and thiourea at 0.50 per cent and 1.00 per cent levels.

The treatments were imposed as foliar sprays at three stages. First spray was given during the first week of Oct.2006 (6 months after tagging); second during first week of Dec.2006 and a follow up spray after the commencement of panicle emergence and flower opening.

History of the shoots prior to the treatment imposition, phenological growth stages etc. were closely monitored right from the tagging; simultaneously noting the variation in the climatic parameters. The trees showed flushing and vegetative shoot growth subsequent to the receipt of a rainfall during September 2006. A temporary withdrawal of rainfall and subsequent resurgence coincided with / probably triggered the events leading to flushing and shoot growth as noted above.

Application of DBC during the first week of September 2006 did not evoke any floral stimulation on the applied shoots, but maintained a vegetative state; but it did result in floral stimulation manifested at various levels when the treatments were imposed during December 2006. The leaves had become dark green and turned stiff by this stage. It was noted in all the treatments other than the thiourea application on cv. Priyor. An early emergence of panicles was conspicuously noted in all the the effective treatments. It was as rapid as seven days in NH4NO3, micronutrient combination in cv. Muvandan and nine days in KNO3-micronutrient combination. KNO3 treatments in cv. Priyor also resulted in early flowering than the control. Intensity of flowering /number of shoots emerging out inflorescences was also significantly promoted by the various effective DBC treatments.

Ammonium nitrate –micronutrient combination and 2 per cent KNO3 were superior in this aspect. The treatments were superior not only in enabling the opening of more number of productive flowers (bisexual flowers) on the panicles, but effecting in a high initial fruit set also.

‘Floral stimulation effect’ of various DBC treatments of nitrogenous compounds, micronutrient combination and thiourea translated further as a ‘floral nutrition effect’ later. Probable extra nutrition result out from the follow up sprays during Dec. 2006 on the panicles at various levels of flower opening may be yet another supplementary factor. All the effective treatments greatly enhanced the growth of the panicles by increasing the various growth parameters, viz., length of the panicle, girth of the panicle at the base and the branching intensity.

Treatments did enhance the girth of the developing fruits; but the effect on fruit length was not conspicuous. Similarly, final retention of fruits at harvest stage was also significantly superior than the control; accordingly increasing the yield and production efficiency as a whole. NH4NO3- micronutrient combination effected the highest yield in cv. Muvandan and 2 per cent KNO3 in cv. Priyor.

In all the effective treatments, level of carbohydrates was found decreasing in shoots and leaves during the panicle development stages whereas the level of nitrogen showed an upward trend. A probable shifting of energy sources to the sites of accelerated growth and development of emerged out inflorescences is indicated with a dilution effect in adjacent leaves and shoots. Accumulated nitrogen including the supplemental content resulted from the applied nitrogen sources might be the basic material for further structural development.

Measurements on photosynthesis and related attributes showed significant variation among the treatments and control at the fruit development stage in cv.Priyor. But, estimation in cv. Muvandan was not consistent and hence the aspect needs further confirmation.

Present investigations clearly indicate the potential of nitrogenous compounds (specifically nitrates and micronutrient combination) as DBC to stimulate flowering and fruiting in humid tropic mangoes. Further standardization on timing of application, maturity of shoots etc. and whole tree trials in farmers field involving more indigenous and other cv. of mangoes of south-west coast comprise the future line of work in this aspect.






The project on ‘Flower bud forcing in humid tropic mangoes using dormancy breakers’ was taken up at Department of Pomology and Floriculture, College of Horticulture during March 2006 to April 2007.

The objective of the experiment was to study the effect of nitrogen compounds, viz., nitrates and their combinations with micronutrients and thiourea on stimulation of flowering in mango cultivars Muvandan and Priyor under the humid tropic situations of Kerala.

The treatments involved KNO3 at 1.00 per cent and 2.00 per cent levels, NH4NO3 at 0.50 per cent and 1.00 per cent, their combination with micronutrients and thiourea at 0.50 per cent and 1.00 per cent levels.

The treatments were imposed as foliar sprays at three stages. First spray was given during the first week of Oct.2006 (6 months after tagging); second during first week of Dec.2006 and a follow up spray after the commencement of panicle emergence and flower opening.

History of the shoots prior to the treatment imposition, phenological growth stages etc. were closely monitored right from the tagging; simultaneously noting the variation in the climatic parameters. The trees showed flushing and vegetative shoot growth subsequent to the receipt of a rainfall during September 2006. A temporary withdrawal of rainfall and subsequent resurgence coincided with / probably triggered the events leading to flushing and shoot growth as noted above.

Application of DBC during the first week of September 2006 did not evoke any floral stimulation on the applied shoots, but maintained a vegetative state; but it did result in floral stimulation manifested at various levels when the treatments were imposed during December 2006. The leaves had become dark green and turned stiff by this stage. It was noted in all the treatments other than the thiourea application on cv. Priyor. An early emergence of panicles was conspicuously noted in all the the effective treatments. It was as rapid as seven days in NH4NO3, micronutrient combination in cv. Muvandan and nine days in KNO3-micronutrient combination. KNO3 treatments in cv. Priyor also resulted in early flowering than the control. Intensity of flowering /number of shoots emerging out inflorescences was also significantly promoted by the various effective DBC treatments.

Ammonium nitrate –micronutrient combination and 2 per cent KNO3 were superior in this aspect. The treatments were superior not only in enabling the opening of more number of productive flowers (bisexual flowers) on the panicles, but effecting in a high initial fruit set also.

‘Floral stimulation effect’ of various DBC treatments of nitrogenous compounds, micronutrient combination and thiourea translated further as a ‘floral nutrition effect’ later. Probable extra nutrition result out from the follow up sprays during Dec. 2006 on the panicles at various levels of flower opening may be yet another supplementary factor. All the effective treatments greatly enhanced the growth of the panicles by increasing the various growth parameters, viz., length of the panicle, girth of the panicle at the base and the branching intensity.

Treatments did enhance the girth of the developing fruits; but the effect on fruit length was not conspicuous. Similarly, final retention of fruits at harvest stage was also significantly superior than the control; accordingly increasing the yield and production efficiency as a whole. NH4NO3- micronutrient combination effected the highest yield in cv. Muvandan and 2 per cent KNO3 in cv. Priyor.

In all the effective treatments, level of carbohydrates was found decreasing in shoots and leaves during the panicle development stages whereas the level of nitrogen showed an upward trend. A probable shifting of energy sources to the sites of accelerated growth and development of emerged out inflorescences is indicated with a dilution effect in adjacent leaves and shoots. Accumulated nitrogen including the supplemental content resulted from the applied nitrogen sources might be the basic material for further structural development.

Measurements on photosynthesis and related attributes showed significant variation among the treatments and control at the fruit development stage in cv.Priyor. But, estimation in cv. Muvandan was not consistent and hence the aspect needs further confirmation.

Present investigations clearly indicate the potential of nitrogenous compounds (specifically nitrates and micronutrient combination) as DBC to stimulate flowering and fruiting in humid tropic mangoes. Further standardization on timing of application, maturity of shoots etc. and whole tree trials in farmers field involving more indigenous and other cv. of mangoes of south-west coast comprise the future line of work in this aspect.