Effect of aluminium on onions, asparagus and squash

Abstract

The effect of Al on the growth and chemical composition of onions (Allium cepa L. cv Pukekohe longkeeper), asparagus (Asparagus officinalis L. cv Lucullus) and squash (Cucurbita maxima L. cv Delica) was investigated using a low ionic strength solution‐culture technique. Onions and asparagus were sensitive to Al while squash was relatively tolerant. The dry matter yields of onion, asparagus and squash tops were reduced 50% by 5, 3, and 26 μM Al in the solution, respectively. Similarly, root dry matter yields were reduced 50% by 1, 5, and 26 μM Al, respectivley. Aluminium reduced the concentration of macro nutrients in both asparagus and onion tops but had no consistent effect on squash tops. Plant analysis and visible symptoms indicated that Al affected magnesium nutrition more than that of any other nutrient.

The roots of squash showed an ability to recover from Al stress by modifying their morphology. However, this effect was insufficient to totally alleviate Al toxicity. Squash also became more sensitive to Al as the growing period progressed. These observations suggest that care is needed in using short term experiments to assess Al tolerance for some species.