Abstract only

Maize crops occupy area of 200-220 thousand hectares, which is the largest portion of the crops in Georgia. However average maize yield in Georgia is as low as 2.0-2.2 t per hectare. The main reason of such low yield of maize grain is the fact Georgian farmers traditionally use local open-pollinated varieties without involving hybrids in maize cultivation. Development of maize hybrids in Georgia is related to the following local peculiarities: 1. Planting area of almost 120-140 thousand hectares, allocated for maize cultivation is occupied with white grain varieties used by the population for food and forage. 2. Subtropics zone where the late maturing varieties are spread (70-80 thousands ha) is the hotbed of maize disease Helminthosporium turcicum. The local varieties are resistant to this disease, while the hybrids of other origin are highly susceptible. To overcome the above mentioned disadvantages introduction of CIMMYT subtropics maize germplasm has begun in Georgia since 2001. In 2001 30 hybrids and synthetics and in 2002- 42 hybrids and 59 lines were received from CIMMYT. This material was studied in humid and dry subtropics environment. In the humid subtropics environment of Ajameti (Zestaponi district) and Senaki (Senaki district) trial stations 30 hybrids of CIMMYT were tested for resistance to fungous diseases in 2001. In 2001 in the dry subtropics environment of Mtskheta district at the experimental station of RI of Agriculture 30 CIMMYT hybrids were tested for resistance to diseases, yield and other characteristics. The tests continued in 2002 and 2003 involving 42 hybrids and 59 lines and 23 hybrids and 35 lines, respectively. In humid subtropics all 30 hybrids demonstrated resistance to Helimnthosporium turcicum. Hybrids retained immunity throughout the whole vegetation period. At the same time 7 out of the 30 tested hybrids proved to be receptive to Ustilago maydlis. Stems and ears were the primary sites of damage. In the dry subtropics all tested hybrids and lines showed absolute immunity to Helminthosporium turcicum during the testing years 2001-2002. Susceptibility to Ustilago maydlis was demonstrated by: 10 out of the 30 hybrids tested in 2001, 15 out of the 42 hybrids and 11 out ofthe 59 lines tested in 2002 and 7 out of the 23 hybrids and 6 out of the 35 lines tested in 2003. In 2001-2003 75 hybrids were tested. The variety Ajameti White was used as a check. The best results were shown by 6 CIMMYT hybrids, which have overyielded the check variety by 4.4 t/ ha (15,2%) as per the two-year data. Two hybrids were developed from the local inbred GP-3 and Ajameti White and CIMMYT synthetic S 91 SIWQ. Good results based at the two years data were received from the final of these hybrids: in 2002 hybrid GP-3 x S91 SIWQ overyielded the check by 1.7 t/ha and yield of the hybrid Ajameti White x 91 SIWQ exceeded the check by 3.92 t/ha (61,1%).

English

0409|AGRIS 0401|AL-Maize Program

Juan Carlos Mendieta

CIMMYT Publications Collection