No abstract

Short-duration pigeonpea [Cajanus cajan (L.) Millsp.] is being targeted for commercial cultivation in more diverse environments than traditional cultivars used in subsistence agriculture. As it is a relatively new crop, information on performance of recently evolved lines and hybrids across a range of environments is lacking. Thirty lines were compared for grain yield in 20 environments representing major areas of cultivation [Patancheru (178N and 728E), Gwalior (268N and 788E) and Hisar (298N and 758E)], soil types and sowing times. Grain yield across environments varied widely from 0.36 to 2.09 t ha À1. Average yield was highest, 1.53 t ha À1 , for hybrid ICPH 8. The genotype-by-environment interaction (GEI) effect analyzed using the additive main effects and multiplicative interaction (AMMI) statistical model was highly signi®cant and was three times more important than the line effects. Line ICPL 83006 was highest 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 homogeneous crop growing environments in which the same genotypes performed best (mega-environments). The average yield with the highest-yielding lines planted in the respective mega-environment was 12.5% higher than when ICPH 8 was planted across all the environments. Signi®cant correlations of crop growth rate, duration of reproductive phase, partitioning and growth habits of lines with GEI patterns suggest that variable performance of the lines across the 20 environments could be due to variation in the physiological components of yield. The results suggest the presence of signi®cant GEI and that its systematic exploitation through selection of the appropriate physiological components for each mega-environment can result in higher average yield across growing environments.

Variation in the trypsin inhibitors (TIs) and the chymotrypsin inhibitors (CIs) among 69 pigeonpea [Cajanus cajan (L.) Millsp.] strains from a wide geographical distribution and among 17 accessions representing seven wild Cajanus species was studied by electrophoretic banding pattern comparisons and by spectrophotometric activity assays. The TI and CI electrophoretic migration patterns among the pigeonpea strains were highly uniform but varied in the inhibitor band intensities. The migration patterns of the inhibitors in the wild Cajanus species were highly species specific. The mean TI activity of pigeonpea strains (2279 units) was significantly higher than that of the wild Cajanus species (1407 units). However, the mean CI activity in the pigeonpea strains (62 units) was much lower than that in the wild species (162 units). Kenya 2 and ICP 9151 were the lowest and the highest, respectively, in both the TI and CI activities among all the pigeonpea strains used in this study. A highly-significant positive correlation was observed between the TI and CI activities. The Bowman-Birk type inhibitors with both TI and CI activities were identified in all the pigeonpea strains and also in the accessions of all the wild species except C. volubilis (Blanco) Blanco. The C. volubilis accession ICPW 169 was found to be 'null' for both CI bands and CI activity. Environment, strain, and environment x strain interaction showed highly-significant effects on both the TI and CI activities. Growing the pigeonpea strains at a different environment from their area of adaptation increased TI and CI activities and also altered the maturity period.

SU M M A R YThe adaptation of extra short duration (ESD) pigeonpea (Cajanus cajan) genotypes to rainfed environments was studied on Alfisols and Vertisols at the ICRISAT Center between 1987 and 1989. Despite a slightly shorter crop duration, the grain yield of ESD genotypes was twice as large on Alfisols as on Vertisols. On both soil types, the rate of growth and grain yield were better in crops sown on time than in those where sowing was delayed. The population levels necessary to maximize yield varied among genotypes on Alfisols, where the grain yield of several ESD genotypes compared favourably with that of ICPL 87, a standard short duration genotype. However, none of the ESD genotypes yielded more than ICPL 87 on the Vertisols. Adaptation del Cajanus cajan de duration extra corta R E S U M E N Se estudio la adaptation de genotipos de Cajanus cajan de duracion extra corta (DEC) a ambientes con precipitaciones naturales en Alfisols y Vertisols, en el ICRISAT Center, entre 1987 y 1989. A pesardeuna duracion de cultivo ligeramente inferior, el rendimiento de grano de los genotipos de DEC fue el doble en Alfisols que en Vertisols. En ambos tipos de suelo el rndice de crecimiento y los rendimientos de grano fueron mejores para las cosechas sembradas a tiempo, que en las sembradas con retraso. Los niveles de poblacion necesarios para maximizar el rendimiento variaron con los' genotipos en los Alfisols, donde el rendimiento de grano promedio de diversos genotipos DEC se compare favorablemente con el del ICPL 87, un, genotipo de corta duracion estandar. No obstante, ninguno de estos genotipos DEC produjo mayor rendimiento que el ICPL 87 en los Vertisols. tPresent address: C/o OAU/STRC, JP 31 SAFGRAD, PO Box 39063, Nairobi, Kenya.ICRISAT journal article number 1268.

Natural out-crossing in pigeonpea (Cajanus cajan (L.) Millsp.) leads to genetic deterioration and in certain environments the out-crossing may be as high as 70%. Studies with partially cleistogamous lines derived from an inter-generic cross indicated that average natural out-crossing in these lines was much lower (2.5%) than that reported earlier for pigeonpea (36.5 %) at ICRISAT Center. Based on seed yield and disease resistance, potential parents such as ICPL 87154 in short-duration determinate, ICPL 87018 in short-duration indeterminate, and ICPL 87159 in medium-duration indeterminate groups have been identified for introgression of the partially cleistogamous trait into pigeonpea.