ICRISAT Archival Report 2006 - The seedlings of success in the ...

days and 34 flowered in 56−60 days (checks ICMB 93111 flowered in 58 days, ICMB 95444 in 55 days and ICMB
93333 in 57 days).
Restorer parent progenies: About 100 progenies (S 6 −S 9 ) were evaluated in the drought nursery during the summer
season, of which 40 were selected based on visual assessment for agronomic traits. Of these, 18 flowered in 46−50
days (checks RIB 3135-18 flowered 55 days and H 77/833-2 in 52 days). In addition, 13 progenies (S 8 −S 10 ) were
evaluated during rainy season and all flowered in 46−55 days (check H 77/833-2 flowered in 44 days).
KN Rai and RP Thakur
Evaluation of hybrid parents progenies: We continued the evaluation in western Rajasthan of four sets of
breeding materials bred specifically for adaptation to the arid zone. These included 48 lines from the Mandor
Restorer Composite, 46 lines from the ICRISAT-CAZRI Maintainer Composite, 24 crosses of adapted B-lines and
11 restorer populations. We evaluated testcrosses of these lines (made with arid zone-adapted testers) to assess their
hybrid potential for grain and stover yields under arid zone conditions. Because of the high degree of inherent
variability in rainfall in the arid zone, years differ significantly in the timing and severity of the inevitable periods of
drought stress, making multi-year evaluations necessary to separate true genotype differences from genotype ×
environment interaction effects. The 2006 rainy season at Jodhpur faced a very late arrival of rains (early August)
but a normal ending of the rainy season (late September), with a total rainfall of about 200 mm. Flowering in all
trials was early (40 days from emergence) and most trials were subject to post-flowering moisture shortage, resulting
in grain yields in the range of 600 to 800 kg ha -1 . Despite this, there were significant differences among the hybrids
for grain and stover yields, and among lines for the general combining ability.
The ICRISAT-CAZRI B-composite was bred by intercrossing maintainer lines thought to be adapted to the arid
zone, and is intended to serve as a source of new, higher yielding seed parents for this zone. Ten lines from this
composite along with controls ICMA 95111 and HMS 7A had a significant general combining ability (GCA) effect
for earliness which is very encouraging. Three of the B-lines, plus control HMS 7A had significant positive GCA for
grain yield. Similarly, three B-lines and two controls (ICMA 93333 and HMS 7A), had significant positive GCA for
stover yield. The basic limitation of many of the lines was their non-significant GCA for biomass in this very short
season environment, which is a common finding in the case of conventionally bred parental lines that have been
selected for high grain yield through high harvest index (HI). In this trial, the relationship of GCA for biomass with
grain (r = 0.78, P