The hidden half of the plants for ‘deep-rooted’ organic agriculture

How can deep roots contribute to organic system

The effect of Intercropping on the Deep Root Development and Nutrient Uptake in a Sugar Beet – Chicory Mixture.

Sustaining an increasing human population with decreasing soil resources is a great challenge of the 21st century. Suboptimal availability of water and N are primary limitations to plant growth in the low-input agroecosystems in developing nations, whereas intensive fertilization at the cost of substantial environmental pollution is a problem in rich countries. The development of crops with greater rooting depth addresses these challenges. Deeper rooting improves water and nutrient uptake, which in turn reduces the need of application of external resources. In our study, we investigate the effect of intercropping on the deep root development and nutrient uptake in sugar beet – chicory mixture. The crops were chosen due to their deep roots and similar growing periods. We hypothesize that in the intercropping system one of the component crops develops roots below the root surface of the other crop, which results in deeper nutrient uptake in comparison to crops growing in pure stands. Crops will be grown in the field as monocultures and in mixture. Root growth will be monitored with minirhizotron method up to 4 m depth. Nutrient uptake will be studied using stable isotopes and ingrowth core methods. Additionally, root biomass estimation through DNA extraction from soil will be investigated. We expect that the results will help to answer the questions of whether the intercropping enhances deeper root growth and nutrient uptake in comparison to sole crops. With this knowledge, exploitation of the subsoil resources by deep roots would contribute to enhanced food production in a sustainable way. The study will start in spring 2018 and preliminary results will be presented

Determining deep root activity in arable fields by the core-labelling technique (CLT)

Introduction: Deep roots have the potential to exploit plant resources otherwise inaccessible. The aim of this study was to develop a method, the Core-Labelling Technique (CLT), to measure root activity down to 2.5 m of soil depth under field conditions. Materials and Methods: Two stainless steel ingrowth-cores, 0.1 m in diameter and 0.55 m in length, were filled with soil labelled with nutrient tracers, i.e., LiCO3, CsCO3, Na2SeO4, RbCO3 and 15NH4Cl. The labelled cores were placed into an access-tube having openings at 1.0 m and 2.5 m of soil depth. They were kept under a lucerne (Medicago sativa) crop for 60 days, after which, the root length density (RLD) and concentration of tracers in shoot biomass (including a control) were measured. Results: RLD of lucerne measured at 1.0 m and 2.5 m of soil depth were 0.022 and 0.007 cm cm-3, respec-tively. Effects of core-labelling on shoot samples were significant for 15N, Li, Cs and Se across the soil depth but not for Rb. On average 6 times higher concentration of 15N (‰) was found at the labelled spot compared to the control. Li and Cs (mg kg-1) at the labelled area showed 2 and 3 times higher concentration than the control, respectively. Regardless of the treatment, core-labelling at 1 m of soil depth resulted in higher concentration of 15N and Cs in comparison to 2.5 m of soil depth. Discussion: To our knowledge, this report illustrates the deepest application of an ingrowth-core method as well as its first adoption of the tracer technique. Our results suggest that 15N, Li, Cs and Se can be feasible tracers for root activity detection in arable subsoil. Conclusions: The CLT can be used as an effective tool for determination of root activity in arable subsoil. We suggest that root research should progress beyond the generic depth-scale in order to discover the relevant yet hidden function of deep roots in crops in the field

Effects of Biodynamic Preparation 500 (P500) Cow Horn Manure on Early Growth of Barley, Pea, Quinoa, and Tomato under Saline Stress Conditions

Large areas of salt-affected soils are found in tropics, especially in Africa, South America and the Middle East. While soil salinity might lead to food insecurity in those regions and affect farmers who are most vulnerable to environmental stress, however, little is known how the abiotic stress can be managed with locally available resources without involving high cost. Decades of practical evidence have demonstrated the benefits of the farm input, called biodynamic preparation 500 (P500) cow horn manure, such as improving crop performance and providing resilience against various stress conditions. Organic agriculture is already seen as an important issue in sustainable crop production in the tropics, but also biodynamic philosophy and agricultural practices are discovering tropical countries. Biodynamic preparations in tropical crop production are already in use, while there is a lack of research concerning their performance. This study was conducted to quantitatively determine the effects of P500 on the early growth of different crops under saline condition. A randomised block design with six replicates in a green house chamber pot trial consisting of two factors, viz., SALT (stressed and control) and PREP (P500 and blank) was run with four crop species that have importance in temperate and tropical countries, viz., barley, pea, quinoa and tomato. Plants were harvested 38 days after sowing and aerial biomass dry matter (DM g) was measured. Results suggest that the application of P500 significantly enhanced the initial biomass production of all tested crops, even under saline conditions (except for tomato). In all crops the biomass yield was significantly improved, average 18.5 % and 16.7 % for non-saline and saline treatments, respectively. Findings suggest that P500 may be a measure to mitigate the stress from adverse environmental conditions for crop plants. Thus, future research with more genotypes, varieties, and crop species, in field conditions where the soils suffer from extreme abiotic stress, should be followed

Identification of deep-rooting crop species in arable subsoil by the minirhizotron technique

Our current understanding of the plant deep root system and its relevance for crop production is limited. A field trial was established in order to monitor the root growth of various deep-rooted crops down to 5 m of soil depth with the minirhizotron technique. Root intensity (RI: intersections m-1) and maximum rooting depth (m) of seven different crop species indicate varying degree of root penetration capacity among the tested crops. Overall, within one season over 89 % of RI was concentrated at 0-1.0 m of soil depth. Sugar beet (1.4 m) as an annual crop showed the most rapid root growth rate (10.6 mm day-1). On average the perennials resulted in 0.7 m of maximum rooting depth (5.6 mm day-1), which indicates their potential to establish deep root systems in coming seasons

Strip Intercropping Promotes Nutrient-Snatching By Deep Roots

The potential of intercropping systems for acquisition of deep-placed nutrients is still not well-known. We examined root growth and nutrient uptake potential of a strip intercropping system with a deep-rooted perennial and a shallow-rooted annual crop species. We compared root growth of sole-cropped winter rye (Rye), rye “intercropped” with an adjacent lucerne strip (Rye|Luc), and sole-cropped lucerne (Luc). Tracer uptake of the crops were measured, including tracer uptake of lucerne grown adjacent to winter rye (Luc-Rye) was determined to reveal the possibility of nutrient-snatching. Our results showed that roots recovered from below the rye in the Rye|Luc intercropping contained roots from both crop species and did not reduce overall root growth. Nutrient uptake potential by Rye|Luc was equivalent to rye as a sole crop, meaning that no competition were observed. Lucerne grown adjacent to labelled rye (Luc-Rye) was able to reach the nutrient source under winter rye by its deep roots. We conclude that strip intercropping shall consider the contrasting root systems of cropping components in order to maximize the resource use efficiency from deep-soil layers

RootPainter: Deep Learning Segmentation of Biological Images with Corrective Annotation

We present RootPainter, a GUI-based software tool for the rapid training of deep neural networks for use in biological image analysis. RootPainter facilitates both fully-automatic and semiautomatic image segmentation. We investigate the effectiveness of RootPainter using three plant image datasets, evaluating its potential for root length extraction from chicory roots in soil, biopore counting and root nodule counting from scanned roots. We also use RootPainter to compare dense annotations to corrective ones which are added during the training based on the weaknesses of the current model

Core-labelling technique (CLT):a novel combination of the ingrowth-core method and tracer technique for deep root study

Background Ingrowth-core method is a useful tool to determine fine root growth of standing crops by inserting root-free soil in mesh-bags for certain period of time. However, the root density observed by the method does not directly explain the nutrient uptake potential of crop plants as it varies over soil depth and incubation time. We have inserted an access-tube up to 4.2 m of soil depth with openings directly under crop plants, through which ingrowth-cores containing labelled soil with nutrient tracers were installed, called core-labelling technique (CLT). The main advantage of CLT would be its capacity to determine both root density and root activity from the same crop plants in deep soil layers. We tested the validity of the new method using a model crop species, alfalfa (Medicago sativa) against three depth-levels (1.0, 2.5 and 4.2 m), three sampling spots with varying distance (0–0.36, 0.36–0.72 and > 5 m from core-labelled spot), two sampling times (week 4 and 8), and two plant parts (young and old leaves) under two field experiments (spring and autumn). Results Using CLT, we were able to observe both deep root growth and root activity up to 4.2 m of soil depth. Tracer concentrations revealed that there was no sign of tracer-leakage to adjacent areas which is considered to be advantageous over the generic tracer-injection. Root activity increased with longer incubation period and tracer concentrations were higher in younger leaves only for anionic tracers. Conclusions Our results indicate that CLT can lead to a comprehensive deep root study aiming at measuring both deep root growth and root activity from the same plants. Once produced and installed, the access-tubes and ingrowth-cores can be used for a long-term period, which reduces the workload and cost for the research. Therefore, CLT has a wide range of potential applications to the research involving roots in deep soil layers, which requires further confirmation by future experiments