## 4 Discussion
### JA Green Mass and Tuber Yield Reports  
The green mass performance of \"early\" JA cultivars at the beginning of September averaged 29.7 t/ha. By the third ten-day period of October, the plants had mostly witnessed and even dried up.  
Analyzing the data in Table 2, it can be noted that at the end of October, for all early cultivars, the value of herbage yield decreased by 0.5-20.7 t/ha due to significant drying of plant tops.  
The green mass performance of \"late\" JA cultivars in early September averaged 47.5 t/ha. By the third ten-day period of October, the plants had significantly increased in weight to an average of 55.8 t/ha.  
The cultivation practices of Jerusalem artichoke in different climatic zones have shown that in \"late\" varieties, the aboveground part grows much larger than in the \"early\" ones, and the plant green mass weight continues to increase up to the onset of frost [16; 28; 55].  
The highest gross yield of tubers in early September was mainly found in the following early-maturing JA cultivars Diyeticheskiy (43.5 t/ha) and Nadezhda (40.8 t/ha). The average yield of the \"early\" cultivars was 27.6 t/ha, while that of the \"late\" cultivars was 13.9 t/ha. In the third ten-day period of October, tubers of all cultivars significantly increased in weight: \"early\" cultivars increased by 2.3-31.1 t/ha and the average yield of tubers rose to 44.5 t/ha; \"late\" cultivars did by 7.0-35.4 t/ha and the average yield was reported as 29.0 t/ha (Table 2).  
Being harvested in early September, the yield of tubers with a fraction of more than 30 mm was obtained from the following varieties: Diyeticheskiy (40.1 t/ha), Korenevskiy (31, 7) and Blank Brekos (27.1 t/ha). The yield slightly lower than 25 t/ha was obtained from the following varieties: Nakhodka (21.2 t/ha), Podmoskovniy (24.4 t/ha) and Skorospelka (16.7 t/ha).  
Jerusalem artichoke is a unique crop which can be used wholly, i.e., all its elements (large tubers, small tubers, stems, leaves, flowers, stolons and roots) [15; 29]. Thus, it is important to take into account the yield of tubers not only of the coarse fraction, but also small tubers (less than 30 mm). At the same time, the largest total (gross) yield was obtained from the following varieties: Diyeticheskiy (43.5 t/ha), Nadezhda (40.8 t/ha) and Korenevskiy (35.9).  
When tubers were harvested in the third ten-day period of October, the highest yield of tubers with a fraction of more than 30 mm in transverse diameter was obtained from the following varieties: Nakhodka (50.3 t/ha), Skorospelka (47.2 t/ha), Podmoskovniy (43.5 t/ha), Nadezhda (41.2 t/ha) and Dieticheskiy (40.1 t/ha).  
At the same time, the total (gross) yield (more than 25.0 t/ha) was obtained in all cultivars with early leaf wilting, as well as for five varieties of late leaf wilting: Spindle (43.9 t/ha), Korenevskiy (42.9 t/ha), Inteces 21 (35.5 t/ha), Inteces (27.1 t/ha) and Novost VIR (25.2 t/ha). The research results confirm the data that suggest the possibility to achieve JA tuber yield up to 54.2-58.5 t/ha [14].  
Being harvested in the first ten-day period of September, the total performance structure of \"early\" JA cultivars comprised on average 52% of green mass, 33% of commercial tubers and 15% of small tubers, while the structure of the \"late\" varieties averaged 77% of green mass, 11% of commercial tubers and 12% of small tubers. Being harvested in the third ten-day period of October, \"early\" varieties produced only 29% of green mass, 58% of commercial tubers and 13% of small tubers; the \"late\" varieties produced 66% of green mass, 22% of commercial tubers and 12% of small tubers (Figure 8). The data obtained can be useful for farmers who are going to cultivate this useful and essential crop, considering the purpose of this crop.