Tigre

On both sampling dates, the plant height, leaf length, leaf weight and pseudostem weight of AS was higher than that of S. In the variables of bulb diameter, bulb weight and number of leaves, no difference was found between the two types of plants on the two sampling dates. In the neck diameter variable, the S were higher than the AS on both sampling dates. Leaf width was favorable to AS on the first sampling date, but no significant difference was observed between the two types of plants in the second sampling (Tables 1 and Table 2).

Platero

Only the variables plant height and leaf length were higher in AS on both sampling dates. No differences were detected in the values of neck diameter, bulb weight, number of leaves and leaf width of diseased and apparently healthy plants on the two sampling dates. The bulb diameter was higher in S on the first sampling date, but there was no difference between the two types of plants on the second sampling date. Leaf weight in the first sampling was favorable to AS, while in the second sampling no difference was detected, an inverse situation occurred with the pseudostem weight, which during the first sampling did not manifest differences between both types of plants but was superior in AS during the second sampling (Tables 1 and 2).

Enc-4

The variables plant height, leaf length and pseudostem weight in AS were greater than those of S on both sampling dates. The values of bulb weight and number of leaves were similar between both types of plants and dates of sampling. The variables leaf width and leaf weight were higher in AS during the first sampling but showed no differences in the second sampling. The values of neck diameter and bulb diameter were higher in S during the first sampling but showed no difference in the second sampling (Tables 1 and 2).

Phytoplasmas are microorganisms whose habitat is restricted to the phloem tissues of their hosts due to their high content of fructose and glucose, which causes a physiological imbalance that leads to the induction of a wide range of symptoms that point towards an alteration in the content of the phloem and loss of hormonal balance (^{Arismendi et al., 2010}). Some of the symptoms observed in garlic plants in Zacatecas such as dwarfism, short leaves and thickening of the pseudostem and bulb could be a direct result of CPt infection.

One of the symptoms that characterize the disease is the thickening of the neck and bulb, both symptoms occurred in the four garlic genotypes studied. During the first sampling, the mean values of these variables were significantly higher in Tigre plants, Ch-6 and Enc-4 for neck diameter, and for Ch-6, Platero and Enc-4 for bulb diameter. During the second sampling, only the neck diameter in the S of the Tigre genotype exceeded those of AS. For the four genotypes and on both sampling dates, the mean values of plant height and leaf length of AS were consistently higher than those of S. Dwarfism in garlic plants infected by phytoplasmas has previously been mentioned by ^{Mollov et al. (2014)}.

The loss in height of S was consistent in both samplings for the S in the four genotypes. On the first sampling date, the percentage of reduction in this variable ranged from 50.9 (Enc- 4, first sampling) to 61.1 (Tigre, second sampling). During the second sampling these percentages increased marginally for all genotypes, although Enc-4 and Platero were the ones that resulted with the lowest (2%) and highest (3.7%) increase, respectively (Table 3).

The length of the leaves of AS was greater than that of S in all cases (genotypes or sampling date), the loss in leaf length, in terms of percentage, was from 30.6 (Enc-4, second sampling) to 44.2% (Tigre, first sampling). The variables leaf weight and pseudostem weight partially showed the same trend: in most cases the values of AS were higher than those of S. The losses in these variables were severe, especially for the Tigre genotype in the first sampling, where the S experienced a reduction of 71.9 and 65.2% in the weight of leaves and pseudostem, respectively (Table 3).

Only in three genotypes the leaf width values of AS were higher than those of S, leading to variable losses between 9.5 (Enc-4, first sampling) and 30% (Tigre, first sampling), in the rest of the genotypes no differences were found between AS and S or between sampling dates. Notably and in both samplings, the number of leaves in AS was higher than in S in the CH-6 genotype. The loss in number of leaves in S was 13.8% and 19.2% for the first and second sampling respectively (Table 3).

The variables of neck diameter, bulb diameter and bulb weight expressed differences in favor of S, especially in the first sampling. For the Tigre genotype, the values of the neck diameter variable favored S on both sampling dates, which meant that the diameter of its bulbs was 5.7% and 32.3% higher than that of AS, in the first and second samplings respectively (Table 3). This contrasts with what was mentioned by ^{Mollov et al. (2014)}, who point out that garlic plants infected by phytoplasmas of the 16Srl group (Aster Yellows) had bulbs of smaller than normal size.

Conclusions

The symptomatology called ‘waxing’ in four genotypes of garlic was found to be associated with consistent losses in plant height and leaf length and to a lesser extent, in the weight of leaves and pseudostem. The rest of the variables evaluated showed erratic behavior between genotypes and sampling dates.