Simulated yield advantages of extending post-flowering development at the expense of a shorter pre-flowering development in soybean

Abstract: Field experiments with soybean demonstrated that the extension of photoperiod after flowering increases both the duration of the post-flowering phase and the production of seeds. These results suggest that cultivars with increased duration of the post-flowering phase could be selected to improve soybean yields. The aims of this paper were to: (a) evaluate the ability of the CROPGRO-soybean model to reproduce the experimental relationships between seed number and duration of the critical phase between first and last pod, and (b) assess the putative benefits and trade-offs of variable durations of the critical phase in a south–north transect in the Pampas of Argentina. We varied the genetic coefficients accounting for photothermal requirements and photoperiod sensitivity of soybean A5409-RG (maturity group V), reducing pre-flowering phase while maintaining time to maturity. The model produced sound estimates of crop phenology and reproduced the positive relationship between seed production and the duration of the critical period between first and last pod found in field studies. Linking the model with long-term climate records for six locations between 31 and 37°S, indicated that substantial yield gains could result from increasing the relative duration of post-flowering phases. A hypothetical cultivar with flowering time typical of cultivars of maturity group III and total cycle typical of cultivars of group V, outyielded the traditional cultivar of group V in most cases. For well-watered crops, extension of the critical period had a positive effect in yield in all seasons and locations, whereas for rainfed crops, the extension of the critical period increased yield in 95% of the simulated scenarios. The magnitude of the effect was strongly asymmetric: yield gains were up to 1Mgha−1 whereas losses were below 0.2Mgha−1. The modelled results in this paper indicate that shortening pre-flowering period without changing the duration of the whole cycle should increase yields in a broad range of latitudes and environmental conditions. [Copyright &y& Elsevier]