Evaluating yield quality and quantity of garlic as affected by different farming systems and garlic clones.

In order to study the effects of different farming systems and garlic (Allium sativum L.) clones on yield quality and quantity of garlic, an experiment was conducted with split plot arrangement with three completely randomized blockes in the 2005 growing season at the experimental research station of Shahid Beheshti University at Zirab, north of Iran. Two factors were involved in the experiment: farming systems in three levels (intensive, conventional and organic farming), as main plots and garlic clones in three levels (Atoo, Hamedani and Khorassani) as sub-plots. The studied factors in this experiment consisted of leaf number, LAI, stem height and diameter, bulb yield, weight of bulbs, number of cloves, weight of cloves and level of allicin. Results showed that the farming systems had significant effect (p<0.05) on LAI, number of plant and bulb yield, but the effect on the other factors was not significant. The highest and lowest bulb yields were obtained in intensive (9.5 ton ha(-1)) and organic (7.4 ton ha(-1)) systems, respectively. All of the top factors were significantly (p< or =0.01) affected by garlic clones. Maximum and minimum yields were obtained from Hamedani, Atoo (9.2 ton ha(-1)) and Virani (7.1 ton ha(-1)) clones, respectively. Level of allicin was not significantly affected by farming systems but, differences among garlic clones were significant. Maximum and minimum allicin yields were obtained from Hamedan (5.96 mg g(-1)) and Virani (4.52 mg g(-1)) clones, respectively. As a result, however, organic farming systems can not influence the yield in short term, but can increase it by applying crop rotation, use of organic fertilizer and cover crops in the long term.

Effect of low storage temperature on some of the flavour precursors in garlic (Allium sativum).

Garlic (Allium sativum) cloves were stored at ambient temperature and 4 degrees C for periods up to six months to establish the effect of position of the individual clove within the bulb and of low storage temperature on the composition of several flavours precursors and other organic sulphur compounds, measured by gradient High Pressure Liquid Chromatography. Levels of alliin, gamma glutamyl allyl cysteine sulphoxide and gamma glutamyl isoallyl cysteine sulphoxide were statistically significantly higher in outer than in inner cloves. There was no statistically significant change in levels of alliin, the major flavour precursor, in cloves stored at 4 degrees C, remaining in the average range 17.5+/-3.8-39.1+/-7.5 mM. However, isoalliin increased significantly during storage at 4 degrees C, rising from an average 0.6+/-0.2 mM (outer cloves) -- 0.7+/-0.4 mM (inner cloves) to 7.1+/-1.7 mM (outer cloves) -- 4.1+/-0.7 mM (inner cloves). A decline in other sulphur-containing compounds, most likely to be the peptides gamma-glutamyl allylcysteine sulphoxide and gamma-glutamyl isoallylcysteine sulphoxide, occurred at the same time and possibly contributed to the increase in the flavour precursor compounds. The degree of chemical changes during storage will be of interest to the food and pharmaceutical industries.