Alternative, recycled sources for mined phosphorus (P) fertilizers are needed to sustain future crop growth. Quantification of phenotypic adaptations and performance of plants with a recycled nutrient source is required to identify breeding targets and agronomy practices for new fertilization strategies. In this study, we tested the phenotypic responses of wheat (Triticum aestivum) and its genetic model, Brachypodium (Brachypodium distachyon), to dried algal biomass (with algae or high or low mineral P) under three growing conditions (fabricated ecosystems (EcoFABs), hydroponics, and sand). For both species, algal-grown plants had similar shoot biomass to mineral-grown plants, taking up more P than the low mineral P plants. Root phenotypes however were strongly influenced by nutrient form, especially in soilless conditions. Algae promoted the development of shorter and thicker roots, notably first and second order lateral roots. Root hairs were 21% shorter in Brachypodium, but 24% longer in wheat with algae compared to mineral high P. Our results are encouraging to new recycled fertilization strategies, showing algae is a nutrient source to wheat and Brachypodium. Variation in root phenotypes showed algal biomass is sensed by roots and is taken up at a higher amount per root length than mineral P. These phenotypes can be selected and further adapted in phenotype-based breeding for future renewal agriculture systems.

Background and Aims: Natural rainfed conditions present drought episodes interspersed with periods of moderate to high soil moisture levels. This study investigates the genetic variation in root-to-shoot growth in response to a wet–drought–wet cycle and aims to identify rice (Oryza sativa) lines differing in drought recovery, focusing on detailed root trait investigations. Methods: In total, 100 different rice accessions were screened under fluctuating moisture across three field seasons for GWAS (genome-wide association study) analysis. In a subset of 20 genotypes, crown root number and leaf length were recorded regularly to calculate a water recovery index (WRI). Two lines contrasting in WRI were grown in a glasshouse experiment to resolve detailed root phenotypes in simulated field drought and re-watering. Key Results: GWAS co-locations indicated drought recovery-associated loci that included candidate genes previously reported for several abiotic stressors. In the subset of 20 genotypes, crown root growth was impacted most by the transition from drought to re-watering. The calculated WRI distinguishes different responses to drought and re-watering. A glasshouse study reproduced the contrasting growth of two selected lines, with ‘ADT 12’ shoot and root growth being strongly impaired by drought, while ‘ARC 18202’ growth was not suppressed. Drought caused a significant decrease in S-type lateral root production in both lines, while a significant increase in L-type lateral root proportion was only found for ‘ADT 12’. These phenotypes were reversed 7 d after re-watering to values of the well-watered control plants. Conclusions: Overall, in-depth root phenotyping confirmed the drought-resistance and recovery ability of ‘ARC 18202’ in the field and highlighted the importance of S-type and L-type lateral root formation already under well-watered conditions prior to drought. ‘ARC 18202’ had a higher amount of thick lateral roots before drought and, therefore, less change in lateral root formation under drought and re-watering conditions.

Cassava is a root storage crop that is important to the starch industry and food security. In this study, the sustainable fertilization of cassava using local placement of struvite, a fertilizer recovered from wastewater, rich in nitrogen, phosphorus, and magnesium, was investigated. It was asked if struvite is a suitable fertilizer for cassava, if it is likely to spread through the substrate (leach), and if roots can proliferate and utilize a concentrated placement of struvite. Cassava was grown in rhizoboxes under different fertilizer placement strategies: unfertilized control, homogeneous fertilizer distribution in the top 20 cm (‘homogenized’), a strip placement (‘layer’) at 20 cm depth, and a localized ‘depot’ at the same depth. Shoot and root growth responses were monitored over 8 weeks. Cassava growth was significantly improved with struvite fertilization. The fertilizer remained localized, with minimcnal spread during the 8 weeks of experimentation. Both the ‘layer’ and ‘homogenized’ struvite placements resulted in comparable biomass production, significantly greater than the unfertilized treatment. Plants in the ‘depot’ placement initially grew similar to the unfertilized treatment as roots took time to locate and proliferate into the fertilizer depot. Afterward, plants in the ‘depot’ treatment grew quickly, resulting in an intermediate biomass at harvest. Notably, cassava exhibited strong root proliferation in response to concentrated struvite, which did not compromise deep rooting but instead appeared to enhance it, increasing specific root length. These findings suggest that strip fertilization with struvite may offer a sustainable fertilization strategy for cassava, warranting further investigation in field trials.

Cassava is a root storage crop that is important to the starch industry and food security. We studied sustainable fertilization of cassava using local placement of struvite, a fertilizer recovered from wastewater, rich in nitrogen, phosphorus, and magnesium. We asked if struvite is a suitable fertilizer for cassava, if it is likely to spread through the substrate (leach), and if roots can proliferate and utilize a concentrated placement of struvite. Cassava was grown in rhizoboxes under different fertilizer placement strategies: unfertilized control, homogenous fertilizer distribution in the top 20 cm (‘homogenized’), a strip placement (‘layer’) at 20 cm depth, and a localized ‘depot’ at the same depth. Shoot and root growth responses were monitored over 8 weeks. Cassava growth was significantly improved with struvite fertilization. The fertilizer remained localized, with minimal spread during the 8 weeks of experimentation. Both the ‘layer’ and ‘homogenized’ struvite placements resulted in comparable biomass production, significantly greater than the unfertilized treatment. Plants in the ‘depot’ placement initially grew similar to the unfertilized treatment as roots took time to locate and proliferate into the fertilizer depot. Afterwards, plants in the ‘depot’ treatment grew quickly resulting in an intermediate biomass at harvest. Notably, cassava exhibited strong root proliferation in response to concentrated struvite, which did not compromise deep rooting but instead appeared to enhance it, increasing specific root length. These findings suggest that strip fertilization with struvite may offer a sustainable fertilization strategy for cassava, warranting further investigation in field trials.