Submitted to: Biotronics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/10/2003
Publication Date: 12/31/2002
Citation: RAO, S.C., SAXENA, K.B., PACHEPSKY, L.B., REDDY, V.R. MODELING PIGEONPEA PHENOLOGY. International Journal of Biotronics. 2002. v. 72. p. 85-100. Interpretive Summary: Pigeonpea is an important forage and grain crop in tropical and subtropical environments. It has potential for use as a summer forage in the southern Great Plains. Quantitative information on the effects of environmental variables like temperature and daylength on pigeonpea growth and development is essential for selection of proper cultivars and planting dates for each climatic region in the Great Plains. A computer model was developed from field data collected at two locations with varying climatic conditions in India and a third site in the U.S. The physiology-based model simulates growth and development of pigeonpea in response to temperature, photoperiod, and precipitation. This model provides a framework for a decision support system (DSS) for cultivar selection and input optimization.
Technical Abstract: Pigeonpea (Cajanus cajan (L.) Millsp.) is a widely grown legume in tropical and subtropical areas. A crop simulation model that can assist in farmer decision-making was developed. The phenological module is one of the major elements of the crop model because accurate prediction of the timing of growth stages is essential for correct modeling of physiological responses under variable field conditions. Phenological observations were conducted during 7 years on 14 early maturing genotypes at three different locations, ICRISAT(17 degrees 32' N, 78 degrees 16' E), Hissar (29 degrees 10' N, 75 degrees 16' E), in India, and at El Reno, OK (35 degrees 40' N, 98 degrees 02' W). Rates of vegetative and reproductive development of pigeonpea, in response to temperature and photoperiod, were developed, parameterized for these three locations and tested with published controlled-environment experimental data. The effects of temperature on growth and development were linear. The effect of photoperiod on both vegetative and reproductive development were nonlinear with five parameters, one of which was a function of location. Analysis showed that interactions between the two major factors of pigeonpea development, temperature and photoperiod, are significant and must be accounted for in the model.