Sprout inhibition, residues and storage quality of garlic in response to preharvest foliage sprays of maleic hydrazide.

MAMANI MORENO, C.; QUEIROZ, M.E.L.R.; SILVA A. A.; BURBA J.L., STADLER T.

Rosario

Congreso; XXXIII Congreso Argentino de Horticultura; 2010

Asociación Argentina de Horticultura

Sprouting is a major cause of losses in stored garlic. There are several methods of sprouting inhibition: the radioinhibición, conservation at low temperatures, and the application of growth regulators. Maleic hydrazide (MH) is a systemic plant growth regulator and herbicide. Argentina is one of the most important garlic exporting countries in the world, where preharvest foliage sprays of MH are used regularly as a method for increasing pos harvest conservation. Sprays of 5600 ppm (2000 g a.i. ha-1) of MH were applied to the foliage of cultivar Rubí INTA at 23 and 10 days prior to harvest. The effect of MH on the garlic was evaluated up to 8 month pos harvest at 15°C of storage temperatures. Laboratory tests to induce sprouting were accompanied by measures of size, weight, pressure, soluble solids, and visual index of dormancy, at four different times during storage. Simultaneously, MH residues in bulbs were determined by HPLC. The inhibition of sprouting resulting from single preharvest foliar spray applied 23 days prior to harvest doesn’t show differences with those treated 10 days prior to harvest. Therefore, application timing is not a delicate issue to MH in garlic as the case in other crops as potatoes where an early treatment will reduce yield and a late treatment will have an insufficient effect on sprouting. Little or no deterioration of quality and with no reduction of yield was observed compared with the control. Nevertheless, the quantified residues had significant differences according to the timing of application. Garlic treated 10 days prior to harvest, they presented major quantity of residues (+39 %).There was a narrow range in the amount of MH residue found in the fertile leaves along the storage period. On the average, about 40% of the MH residues were found in the cloves contained within the external fertile leaf; and 60%, in the cloves corresponding to the internal fertile leaf. MH residue levels declined 32 % during storage period. Finally it is concluded that MH proved to be effective against sprouting, without marked effects in the physiological parameters, since after 8 months storage there were no highly significant differences in the quality parameters. Nevertheless they presented significant differences in the concentrations of residues according to the timing of application. Further investigations are needed to determine the effect of MH on catabolic pathways involved in sprouting of garlic bulbs.