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BULBING PHYSIOLOGY IN GARLIC (ALLIUM SATIVUM L.) CV. “ROSADO PARAGUAYO” III. NUTRIENT CONTENT IN GARLIC PLANTS : ITS RELATION TO GROWTH DYNAMICS AND BULB MORPHOGENESIS
Rosado Paraguayo.
III, Nutrient content in garlic plants : its relation to growth dynamics and bulb morphogenesis.
In garlic, the relation between shoot nutrient content and bulb growth and morphogenesis have not been previously studied in detail.
Determining the initiation of nutrient transport from shoot to bulb would allow to estimate bulb demand during crop cycle.
The purpose of this work is to determine nutrient content in shoots and bulbs during garlic ontogeny, in relation to the dynamics of bulb growth and morphogenesis.
Trials were performed at an experimental plot of the Faculty of Agronomy, National University of Cordoba.
N, P and K in soils were determined at the begining of the trial.
Medium and large seed cloves obtained from the second and third fertile leaf were sown.
Twenty plants were sampled at random every 15 days starting 10 days after emergence.
Bulbing index (BI), N, P, K, Ca and S in bulbs and shoots, and dry weight (SDW) and total soluble carbohydrates (TSSC) in shoots were determined.
N and K are the most abundant elements and show the same tendency both in shoots and bulbs.
No significant changes in nutrient were observed during sprouting.
Nutrient changes become important between the initiation of shoot growth (30 DAS) and the begining of the bulb filling stage (140 DAS, BI : 0.92 ± 0.04). Maximum shoot growth and TSSC are reached at this stage.
The increase in TSSC can be associated to bulb morphogenesis, though it could not be established whether it is cause or effect.
The C \ N ratio increased 140 DAS when TSSC was still high, wich may be associated to an increase in membrane permeability, as has been observed in barley, facilitating bulb filling.
At this point the sink-source relation between shoot and bulb is inverted, and the first signs of leaf senescence become evident.
These results indicate that the critical period for fertilizing garlic would be between the initiation of shoot growth and the begining of bulb filling.
Fertilizing after bulbing (BI: 0.5 ± 0.04) when the translocation of photosyntates and nutrients has begun, would not significantly affect productivity.