Sowing summer grain crops early in late winter or spring: Effects on root growth, water use, and yield

CONTEXT. Drought and extreme heat at flowering are common stresses limiting the yield of summer crops. Adaptation to these stresses could be increased by sowing summer crops early in late winter or spring, to avoid the overlap with critical crop stages around flowering. Though little is known about the effects of cold weather on root growth, water use and final grain yield in sorghum. OBJECTIVE. To research the effects of cold conditions in early sowing sorghum on crop and root growth and function (i.e., water use), and final grain yield. METHODS. Two years of field experiments were conducted in the Darling and Eastern Downs region of Qld, Australia. Each trial consisted of three times of sowing (late winter, spring, and summer), two levels of irrigation (i.e., rainfed and supplementary irrigated), four plant population densities (3, 6, 9 and 12 pl m⁻²), and six commercial sorghum hybrids. Roots and shoots were sampled at the flag leaf stage on three times of sowing, two levels of irrigation, and three replications, for a single hybrid and a single plant population density (9pl m⁻²). Crop water use and functional root traits were derived from consecutive electromagnetic induction (EMI) surveys around flowering. At maturity crop biomass, yield and yield components were determined across all treatments. RESULTS. The combinations of seasons, times of sowing and levels of irrigation created large variations in growth conditions that affected the growth and production of the crops. Early sowing increased yield by transferring water use from vegetative to reproductive stages increasing water use efficiency (kg mm⁻¹ available water). The larger yields in the early and spring sown crops were associated to larger grain numbers, particularly in tillers. Cold temperatures in the early sowing times tended to produce smaller crops with smaller rooting systems, smaller root-to-shoot ratios, and larger average root diameters. Total root length and root length density increased with increasing pre-flowering mean air temperatures up to 20°C. Linear relationships were observed between an EMI derived index of root activity and the empirically determined values of root length density (cm cm⁻³) at flowering. CONCLUSIONS. Sowing sorghum, a summer crop, early in late winter or spring transferred water use from vegetative stages to flowering and post-flowering stages increasing crop water use efficiency. The higher grain numbers in early sown crops were related to higher grain numbers in tillers. Root length and root length density were reduced by pre-flowering mean temperatures lower than 20°C, indicating a need to increase cold tolerance for early sowing. The EMI derived index of root activity has potential in the development of high throughput root phenotyping applications

Transformational agronomy by growing summer crops in winter: The cropping system and farm profits

The idea that “Yield is King” fails to acknowledge that what matters most to farmers is farm profits and risk, rather than yield. This is because decisions made in one season will affect options and crop performance over the next few years. Therefore, quantifying the longer-term impacts of innovation adoption is important. We used the Agricultural Production Simulation model (APSIM) to simulate and investigate the implications of adopting rain-fed winter sown sorghum in the Australian northern grains region. Results indicate that within a crop rotation early-planted sorghum will tend to decrease median sorghum crop yields but increase the following winter crop yields. This appears to have a marginal economic effect in Breeza and Dalby but encouraging results in Emerald. The inclusion of chickpea within the rotation increased returns in the best seasons with little change to downside risks in poor seasons

Transformational agronomy by growing summer crops in winter: The cropping system and farm profits

The idea that “Yield is King” fails to acknowledge that what matters most to farmers is farm profits and risk, rather than yield. This is because decisions made in one season will affect options and crop performance over the next few years. Therefore, quantifying the longer-term impacts of innovation adoption is important. We used the Agricultural Production Simulation model (APSIM) to simulate and investigate the implications of adopting rain-fed winter sown sorghum in the Australian northern grains region. Results indicate that within a crop rotation early-planted sorghum will tend to decrease median sorghum crop yields but increase the following winter crop yields. This appears to have a marginal economic effect in Breeza and Dalby but encouraging results in Emerald. The inclusion of chickpea within the rotation increased returns in the best seasons with little change to downside risks in poor seasons

Seed exchange among common bean producers in Uganda: Examples of networks that stimulate adoption and market participation

Seed exchange networks represent the patterns and processes of seed movement in society, a fundamental component of crop production with major biological and social implications. These networks can furthermore explain patterns in household willingness to experiment with and adopt new and unusual varieties. This body of research focused on common bean (Phaseolus vulagris) seed exchange networks among household producers in western Uganda, where household producers represented over 70% of the population. Among these household producers, nearly all produced beans for either subsistence or commercial purposes and exchanged seeds through social networks. This study provided evidence that regional- and community-level seed exchange networks contributed to unique patterns of seed adoption and adoption-related outcomes. Households with different regional- and community-level seed exchange networks had distinct seed management practices and seed security constraints. Adoption, in situ genetic diversity and evidence of landrace replacement varied across households that participated in different seed exchange networks. Finally, the impact of public sector breeding activities on adoption and household market participation also varied across households that participated in different seed exchange networks. The study found a unique example among one community-level seed exchange network (Kakindo Sustainable Cooperative) of seed management practices that achieved both diversification and conservation of bean varieties and stimulated participation in local seed markets. The analysis suggests that a households' ability to simultaneously increase diversity of household seed stocks and conserve landraces was accomplished through a combination of conservative management of the more historically predominant Andean varieties and willingness to adopt and experiment with rare Mesoamerican varieties

Enhancing the benefits of value chain development: Addressing gender disparities in Kenyan and Ugandan common bean value chains

This study contributed to a better understanding of current gender disparities that can help to ensure future inclusive market development and associated benefits. The analysis is based on empirical evidence from female and male small and medium enterprise (SME) owners along the common bean value chain that served urban and peri-urban bean markets in Kenya and Uganda. The value chain was evaluated based on cross-sectional data collected from 349 interconnected small and medium enterprises (SMEs). SMEs spanned three value chain levels, namely traders and wholesalers, which were dominated by male proprietors, and shopkeepers, which were dominated by female-proprietor

Value chain development to reach the nutritional needs of the urban poor: The role of brokers and SMEs for the commercialization of common beans in East Africa

This study addresses the need to empirically determine the effect of brokers on the performance of SMEs in the common bean value chains of Uganda and Kenya. Contrary to the conventional portrayal of brokers as scam artists, this analysis determined that broker use benefited SMEs by increasing profit margins of bean traders, wholesalers and retailers along the value chain

Enhancing the benefits of value chain development: Addressing gender disparities in Kenyan and Ugandan common bean value chains

This study contributed to a better understanding of current gender disparities that can help to ensure future inclusive market development and associated benefits. The analysis is based on empirical evidence from female and male small and medium enterprise (SME) owners along the common bean value chain that served urban and peri-urban bean markets in Kenya and Uganda. The value chain was evaluated based on cross-sectional data collected from 349 interconnected small and medium enterprises (SMEs). SMEs spanned three value chain levels, namely traders and wholesalers, which were dominated by male proprietors, and shopkeepers, which were dominated by female-proprietor

Value chain development to reach the nutritional needs of the urban poor: The role of brokers and SMEs for the commercialization of common beans in East Africa

This study addresses the need to empirically determine the effect of brokers on the performance of SMEs in the common bean value chains of Uganda and Kenya. Contrary to the conventional portrayal of brokers as scam artists, this analysis determined that broker use benefited SMEs by increasing profit margins of bean traders, wholesalers and retailers along the value chain