Abstract only

Along with other factors, field emergence and resulted density of crop is of great importance for securing high grain yield in wheat. Frequently, a greater portion of the planted seeds fails to emerge under field conditions and a great difference between the laboratory germination and field emergence rates is observed. As a result, thin plant stand are obtained. Factors that influence on field germination rate of seeds are very diverse. Numerous studies have failed to explain comprehensively the causes of such significant variation in field germination. However, the results of some works investigating the problem can be summed up already today. Some Armenian and foreign authors suggest the most influential among the factors influencing field germination are natural properties of seeding material and its quality, water and temperature conditions during seed germination, pre sowing tillage of soil and its fertility, predecessors, seeding rates and dates, the level of infestation of soil and seeding material with diseases (particularly fungi) and pests, and the depth of seedbed. It should be also mentioned that under different environmental conditions the impact of the listed factors manifests itself differently. In some environments, failure to germinate may be caused by low temperature and increased soil humidity, while water stress may hinder germination in other environments. In certain circumstances, field germination of seed can be essentially affected by the presence of diseases and pests, in other circumstances -by the seeding material's quality or soil tillage system. Hence, the most important objective of the present study is revealing the causes of low field germination of seeds under specific environmental conditions of growing winter wheat Bezostaya I. The results of our study showed that field germination of Bezostaya 1 under different environmental conditions was different in line with long-term data of the state variety test plots. In general, average field germination of winter wheat throughout the republic makes 82.6%, i.e. 17.4 kg out of every 100 kg of planted seeds do not actually take part in the establishment of the prospective yield and are lost. If these figures are re-calculated accross the whole sowing area, it will appear that 2.5-3.0 tons of seed at least are annually lost in the republic with regard to just one variety of wheat- Bezostaya 1 .Due to non- germination of a portion of seeds, the emergence density is reduced. Thus, under rain-fed conditions of the Zangezur zone, only 80.5% of planted seeds emerge, while in the Shiral zone and the Sevan basin even less 72.3% and 78.3%, respectively. Based on the data obtained, it may be concluded that there is association between the number of the days from planting to emergence and rate of field germination of seeds. Similarly, stand density depends on the number of the days from planting to emergence. Thus, under rainfed conditions of the northeastern zone, when winter wheat emerged in 12-15 days, field germination rate was equal to 85.0%. When wheat emerged in 22- 15 days, the germination rate dropped to 79.0%. On the Shirak plateau, germination rate of72.5% was observed when wheat emerged in 9-11 days, while only 56% of the seeds germinated when wheat emerged between the 40th-49th days. This can be presumably explained by the fact that the longer the period between sowing and emergence, the more will be the extent of seed destruction and damage. As a result, a portion of seeds produce weak, non-viable shoots that easily perish under unfavorable environmental conditions. The results of our study have shown that winter wheat plants perish generally in the spring-summer period, so the issue of irrigation is of primary concern during this time. To sum up, it may be concluded that in different agricultural zones of Armenia seeds of wheat variety Bezostaya 1 have different field survival rate. As a result, significant variation in the difference between the number of planted seeds and the number of produced shoots is observed, which essentially reduces the percentage of survived plants that produce grain by harvest.

English

0409|AGRIS 0401|AL-Wheat Program

Juan Carlos Mendieta

CIMMYT Publications Collection