Tillering and prolific inbreds
--Bongho Choe, Heebong Lee, Wonkoo Lee and Heechung Ji

Since we reported the tillering characteristics of some of the Korean local open pollinated flint lines in 1980, our efforts to develop high performing tillering hybrids have been continued (MNL 56:62, 1982; IBPGR Newsletter 68:1, 1986; 13th Cong. EUCARPIA, 1985; MNL 62:54, 1987; MNL 63:75, 1988; SABRAO 19:119-122, 1987; MNL 67:108, 1993). We have developed four tillering inbreds, IK1, IK2, IK3 and IK4. IK1 and IK3 inbreds were strictly developed from Korean local flint lines and IK2 inbred was developed from crosses between IK1 and U. S. derived dent type. All inbreds were selfed for more than ten generations and selected based on the number of tillers and tillering characteristics. Table 1 shows some of the unique characteristics of the inbreds.

Table 1. Main characteristics of three tillering inbreds.
Inbreds Main stem ht cm Tiller* ht cm Tillers plant-1 Effective tillers plant-1 Ear ht cm Ears plant-1 100 kernel weight gr
IK1 158.0 118. 5 2.1 2.1 70.3 4.6 15.3
IK2 160.5 90.4 1.9 1.5 80.7 2.5 16.5
IK3 165.3 100. 3 1.7 1.5 78.3 3.2 13.4
*average of first and second tiller heights

The characters shown in Table 1 were all based on trials conducted in Korea. Our past experience shows that the inbreds failed to show tillers when planted at Los Banos, Philippines, probably due to high temperature (MNL 67:108, 1993). The inbreds shown in Table 1 were planted on May 1 at Taejon, Korea. The plant density was about 50,000 ha-1. The tiller heights of inbreds are shorter than the main stem height. Each inbred has one to two tillers per plant. The number of ears per plant ranged from three to five. The 100 kernel weights of inbreds are comparatively low, ranging from 13 to 17 grams. In addition to these three inbreds, IK4 was recently developed and its general characteristics are reported in this newsletter (see previous article). 

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