Dynamics of productivity in pigeonpea [Cajanus cajan (L.) Millsp.] in subtropical Australia

Pigeonpea productivity can be enhanced by optimally matching the physiology of genotypes to environmental conditions. Information on crop responses to the environment has been lacking for the short-duration pigeonpea genotypes, which are being trialed to develop the Australian pigeonpea industry. The objective of this study was to examine the dynamics of productivity in relation to radiation use efficiency (RUE) and its influence on yield partitioning. Seven field trials, employing three pigeonpea [Cajanus cajan (L.). Millsp.] genotypes, were established at the Gatton Campus, the University of Queensland, Australia, in 2017/2018 and 2018/2019 summer seasons. The study reveals that leaf area development, influenced by growing environment, genotypes, and their interactions, were the key factors for the differences in leaf area duration and RUE. Pigeonpea planted in December had higher seasonal (1.11 g MJ−1) as well as reproductive (0.71 g MJ−1) RUE, resulting in significant differences in total dry matter (TDM) and grain yield (GY). GY was positively associated with seasonal RUE (R2 = 0.62), and the relationship was stronger (R2 = 0.83) for the reproductive phase (RUE(R)). The positive association between GY and RUE(R) suggested that maintaining optimum leaf area during the grain filling period is crucial to achieve higher productivity. Variations in GY were related to amount and rate of TDM accumulation before flowering (R2 = 0.51 and R2=0.53, respectively). Hence, achieving greater TDM before flowering was determinant for achieving higher productivity. The present study provided updated information on dynamics of productivity that will enable more comprehensive modelling of pigeonpea adaptation under subtropical conditions.