Testing pearl millet and cowpea intercropping systems under high temperatures

With the potential threat of more frequent climate extremes putting semi-arid crop production in jeopardy, there is a need to establish more climate resilient cropping practices. Intercropping is often practiced by farmers in semi-arid regions and is perceived as a risk reducing practice. However, there is little knowledge of how and to what extent it can be a viable option under future conditions. As testing a complex adaptation strategy in controlled environments is difficult, conducting field experiments in the dry season offers opportunities to test cropping systems under extreme but real-world conditions. Consequently, a field trial was run in semi-arid India over a two-year period (2015 and 2016) in the dry and hot (summer) season. These trials were set up as a split-split-plot experiment with four replicates to assess the performance of simultaneously sown sole versus intercropped stands of pearl millet and cowpea, with two densities (30 cm and 60 cm spacing between rows - both with 10 cm spacing within rows), and three water treatments (severe stress, partial stress, and well-watered) applied with drip irrigation. Results showed that intercropping pearl millet led to a significantly lower total grain yield in comparison to the sole equivalent. Pearl millet’s highest yields were 1350 kg ha−1 when intercropped and 2970 kg ha−1 when grown as a sole crop; for cowpea, 990 kg ha−1 when intercropped, and 1150 kg ha−1 as a sole crop. Interestingly, even when maximum daily temperatures reached up to 42.2 °C (on Julian day 112 in 2016), well-watered, pearl millet produced reasonable yields. Cowpea yields were often lower than 1000 kg ha−1. Only under the highest irrigation treatment (well-watered) sole cropped, low density were yields of 1150 and 1110 kg ha−1 achieved in 2015 and 2016, respectively. We conclude that successful intercropping systems must be highly specific to conditions and demands. More research would be needed to identify suitable cowpea genotypes and planting densities that could allow for higher intercropped pearl millet yields

Methods for environment: productivity trade-off analysis in agricultural systems

Trade-off analysis has become an increasingly important approach for evaluating system level outcomes of agricultural production and for prioritising and targeting management interventions in multi-functional agricultural landscapes. We review the strengths and weakness of different techniques available for performing trade-off analysis. These techniques, including mathematical programming and participatory approaches, have developed substantially in recent years aided by mathematical advancement, increased computing power, and emerging insights into systems behaviour. The strengths and weaknesses of the different approaches are identified and discussed, and we make suggestions for a tiered approach for situations with different data availability. This chapter is a modified and extended version of Klapwijk et al. (2014)

Adapting to climate change in The Netherlands: an inventory of climate adaptation options and ranking of alternatives

In many countries around the world impacts of climate change are assessed and adaptation options identified. We describe an approach for a qualitative and quantitative assessment of adaptation options to respond to climate change in the Netherlands. The study introduces an inventory and ranking of adaptation options based on stakeholder analysis and expert judgement, and presents some estimates of incremental costs and benefits. The qualitative assessment focuses on ranking and prioritisation of adaptation options. Options are selected and identified and discussed by stakeholders on the basis of a sectoral approach, and assessed with respect to their importance, urgency and other characteristics by experts. The preliminary quantitative assessment identifies incremental costs and benefits of adaptation options. Priority ranking based on a weighted sum of criteria reveals that in the Netherlands integrated nature and water management and risk based policies rank high, followed by policies aiming at 'climate proof' housing and infrastructure

Evidence for increasing global wheat yield potential

Wheat is the most widely grown food crop, with 761 Mt produced globally in 2020. To meet the expected grain demand by mid-century, wheat breeding strategies must continue to improve upon yield-advancing physiological traits, regardless of climate change impacts. Here, the best performing doubled haploid (DH) crosses with an increased canopy photosynthesis from wheat field experiments in the literature were extrapolated to the global scale with a multi-model ensemble of process-based wheat crop models to estimate global wheat production. The DH field experiments were also used to determine a quantitative relationship between wheat production and solar radiation to estimate genetic yield potential. The multi-model ensemble projected a global annual wheat production of 1050 +/- 145 Mt due to the improved canopy photosynthesis, a 37% increase, without expanding cropping area. Achieving this genetic yield potential would meet the lower estimate of the projected grain demand in 2050, albeit with considerable challenges