Evaluation of various genotypes of carrots in the nursery of initial breeding forms

The investigations were conducted on the fields of the Kazakh Research Institute of Potato and Vegetable Growing located on the northern slope of the Zailiysky Alatau, 40 km to the west of Almaty city, under irrigation conditions. The soil of the experimental site is dark chestnut with medium-loamy structure. 37 carrot accessions with different geographic origins were the object of the study in the nursery of the initial breeding forms to evaluate their productivity and field resistance to foliar diseases such as Alternaria, Powdery Mildew. When symptoms expressed maximally 1.5 months before the harvest of carrot, visual assessment of leaf surface damaged by foliar infections was carried out according to the scale of infection, where 0 meant no damaged leaves; 1 meant very light damage (1-10% of leaves); 2 meant light damage (11-25% of leaves); 3 meant medium damage (26-50% of leaves); 4 meant severe damage (over 51% of leaves). The visual observation showed that two breeding accessions CR00655 and CR01253 had immunity to powdery mildew that maximally spread out over other carrot accessions approaching of 100% of damage of leaf surface with the score from 1.8 to 3.8 points, when disease developing from 45.0 to 93.8%. Alternaria spread on carrot plants not very intensively, only 17% of plants in the nursery were hardly attacked at 0.1-0.4 points as scored. The correlation analysis showed the absence of any link between characteristics of productivity and damage parameters caused by foliar diseases at r=0,005-0,225.