GENOTYPE-BY-ENVIRONMENT INTERACTION EFFECT ON YIELD AND ITS PHYSIOLOGICAL BASES IN SHORT-DURATION PIGEONPEA

Short-duration pigeonpea [Cajanus cajan (L.) Millsp.] is being targete d for commercial cultivation in more diverse environments than traditi onal cultivars used in subsistence agriculture. As it is a relatively new crop, information on performance of recently evolved lines and hyb rids across a range of environments is lacking. Thirty lines were comp ared for grain yield in 20 environments representing major areas of cu ltivation [Patancheru (17 degrees N and 72 degrees E), Gwalior (26 deg rees N and 78 degrees E) and Hisar (29 degrees N and 75 degrees E)], s oil types and sowing times. Grain yield across environments varied wid ely from 0.36 to 2.09 t ha(-1). Average yield was highest, 1.53 t ha(- 1), for hybrid ICPH 8. The genotype-by-environment interaction (GEI) e ffect analyzed using the additive main effects and multiplicative inte raction (AMMI) statistical model was highly significant and was three times more important than the Line effects. Line ICPL 83006 was highes t yielding in one, ICPL 87101 in two, hybrids ICPH 9 in four and ICPH 8 in 13 environments. Based on the range of adaptation of the highest yielding lines, the 20 environments were grouped into four fairly homo geneous crop growing environments in which the same genotypes performe d best (mega-environments). The average yield with the highest-yieldin g lines planted in the respective mega-environment was 12.5% higher th an when ICPH 8 was planted across all the environments. Significant co rrelations of crop growth rate, duration of reproductive phase, partit ioning and growth habits of lines with GEI patterns suggest that varia ble performance of the lines across the 20 environments could be due t o variation in the physiological components of yield. The results sugg est the presence of significant GEI and that its systematic exploitati on through selection of the appropriate physiological components for e ach mega-environment can result in higher average yield across growing environments. (C) 1998 Elsevier Science B.V. All rights reserved.