Search

Establishing desirable cropping systems with higher fertilizer-use efficiency and lower risk of environmental pollution is a promising approach for more sustainable agriculture development. Intercropping may facilitate phosphorus (P) uptake and reduce P-fertilizer application rates. However, how root-root interactions mediate enhanced P-fertilizer-use efficiency in intercropping under field conditions remains poorly understood. Using a long-term field experiment established in 2009, where there have been three P-fertilizer application rates (0, 40, and 80 kg P ha−1) and nine cropping systems (four intercropping combinations and corresponding monocultures), we calculated aboveground biomass, grain yield, aboveground P content, P-use efficiency indicators, e.g., the apparent recovery efficiency of applied P, and diversity effects. We also investigated the P-related physiological and morphological traits of crop species and linked root traits with agronomic indicators. We found that 12 years of intercropping significantly increased productivity, shoot P content, agronomic efficiency of applied P, and the apparent recovery efficiency of applied P in all combinations compared with the weighted means of corresponding monocultures; intercropping with 40 kg P ha−1 application showed relatively high productivity, P content and P-use efficiency. The P-uptake advantage in intercropping was mainly related to the positive complementarity effect. The companion crop species (i.e. faba bean, oilseed rape, chickpea, and soybean) exhibited greater P-mobilizing capacity than sole maize. Intercropped maize exhibited greater root physiological, e.g., rhizosheath phosphatase activity and carboxylates (proxied by leaf manganese concentration), and morphological traits (e.g., specific root length) than sole maize, partly related to facilitation by efficient P-mobilizing neighbors. The greater P-use efficiency was mainly contributed by morphological traits of maize rather than traits of companion crop species. We highlight that the enhanced P-use efficiency in intercropping systems is partly mediated by belowground facilitation, and desirable intercropping systems have the potential to save P-fertilizer input and improve the sustainability of P management in agroecosystems. [ABSTRACT FROM AUTHOR]

Arbuscular mycorrhizal (AM) fungi can affect plant growth by regulating competition. Nutrient-deficient karst habitats contain abundant plants that compete for nutrients through interspecific or intraspecific competition, involving the nutritional transformation of litter decomposition. However, how plant competition in the presence of AM fungi and litter affects root development and nutrition remains unclear. A potted experiment was conducted, including AM fungus treatment with or without Glomus etunicatum, the competition treatment concerning intraspecific or interspecific competition through planting Broussonetia papyrifera and Carpinus pubescens seedlings, and the litter treatment with or without the mixture of B. papyrifera and C. pubescens litter leaves. The root morphological traits were analyzed, and nitrogen (N), phosphorus (P), and potassium (K) were measured. The results showed that AM fungus differently affected the root morphological development and nutrition of both competitive plants, significantly promoting B. papyrifera roots in the increase of dry weight, length, volume, surface area, tips, and branches as well as N, P, and K acquisitions regardless of litter addition. However, there was no apparent influence for C. pubescens roots, except for the diameter in the interspecific competition with litter. The root dry weight, length, volume, surface area, and tips of B. papyrifera under two competitive styles were significantly greater than C. pubescens regulated by AM fungus, presenting significant species differences. The responses of the relative competition intensity (RCI) on root morphological and nutritional traits indicated that AM fungus and litter both asymmetrically alleviated more competitive pressure for B. papyrifera than C. pubescens, and the interspecific competition facilitated more root morphological development and nutrition utilization by endowing B. papyrifera root superiority relative to C. pubescens compared with the intraspecific competition. In conclusion, interspecific competition is more beneficial for plant root development and nutrition than intraspecific competition in the presence of AM fungus and litter via asymmetrically alleviating competitive pressure for different plants. [ABSTRACT FROM AUTHOR]

Understanding the response of plant community to degradation is fundamentally important for grassland conservation and management. The objective of this study is to examine the changes in soil properties and plant characteristics along a degradation gradient in alpine steppe, and explore the potential mechanisms that biotic and abiotic controls regulate plant community variations. We chose seven sequent degrees of degradation, and conducted a field survey as well as soil and plant samplings in an alpine steppe in Northern Tibet. The results showed that soil water content (SWC), soil compaction (SCOM), soil total carbon (STC), and total nitrogen (STN) dramatically decreased along the degradation gradient. The species richness, overall aboveground biomass (AGB), and AGB of graminoids were apparently reduced with increasing degradation, while AGB of forbs slightly increased. The increasing degradation levels induced a significant increase in the trade-off value of AGB of forbs, which was negatively associated with SWC, SCOM, STC, STN, and soil available nitrogen. The mean root length of forbs was significantly longer than that of graminoids (P < 0.05). Moreover, the mean root diameter of the top 1/3 part of forbs was remarkably thicker than that of graminoids (P < 0.05). These findings indicate that the degradation-induced cohesionless soils with insufficient water and nutrients together with the divergent root morphological traits of graminoids and forbs determine the plant community structure shift with grassland degradation. This study can improve the understanding of community succession of grassland degradation, and provide guidance for the management of degraded alpine steppe on the Tibetan Plateau.

Root system architecture and morphological diversification in wild accessions are important for crop improvement and productivity in adzuki beans. In this study, via analysis using 2-dimensional (2D) root imaging and WinRHIZO Pro software, we described the root traits of 61 adzuki bean accessions in their early vegetative growth stage. These accessions were chosen for study because they are used in Korea’s crop improvement programs; however, their root traits have not been sufficiently investigated. Analysis of variance revealed a significant difference between the accessions of all measured root traits. Distribution analysis demonstrated that most of the root traits followed normal distribution. The accessions showed up to a 17-fold increase in the values in contrasting accessions for the root traits. For total root length (TRL), the values ranged from 82.43 to 1435 cm, and for surface area (SA), they ranged from 12.30 to 208.39 cm2. The values for average diameter (AD) ranged from 0.23 to 0.56 mm. Significant differences were observed for other traits. Overall, the results showed that the accession IT 305544 had the highest TRL, SA, and number of tips (NT), whereas IT 262477 and IT 262492 showed the lowest values for TRL, SA, and AD. Principal component analysis showed an 89% variance for PC1 and PC2. K-mean clustering explained 77.4% of the variance in the data and grouped the accessions into three clusters. All six root traits had greater coefficients of variation (≥15%) among the tested accessions. Furthermore, to determine which root traits best distinguished different accessions, the correlation within our set of accessions provided trait-based ranking depending on their contribution. The identified accessions may be advantageous for the development of new crossing combinations to improve root features in adzuki beans during the early growth stage. The root traits assessed in this study could be attributes for future adzuki bean crop selection and improvement.

Root system architecture and morphological diversification in wild accessions are important for crop improvement and productivity in adzuki beans. In this study, via analysis using 2-dimensional (2D) root imaging and WinRHIZO Pro software, we described the root traits of 61 adzuki bean accessions in their early vegetative growth stage. These accessions were chosen for study because they are used in Korea's crop improvement programs; however, their root traits have not been sufficiently investigated. Analysis of variance revealed a significant difference between the accessions of all measured root traits. Distribution analysis demonstrated that most of the root traits followed normal distribution. The accessions showed up to a 17-fold increase in the values in contrasting accessions for the root traits. For total root length (TRL), the values ranged from 82.43 to 1435 cm, and for surface area (SA), they ranged from 12.30 to 208.39 cm2. The values for average diameter (AD) ranged from 0.23 to 0.56 mm. Significant differences were observed for other traits. Overall, the results showed that the accession IT 305544 had the highest TRL, SA, and number of tips (NT), whereas IT 262477 and IT 262492 showed the lowest values for TRL, SA, and AD. Principal component analysis showed an 89% variance for PC1 and PC2. K-mean clustering explained 77.4% of the variance in the data and grouped the accessions into three clusters. All six root traits had greater coefficients of variation (≥15%) among the tested accessions. Furthermore, to determine which root traits best distinguished different accessions, the correlation within our set of accessions provided trait-based ranking depending on their contribution. The identified accessions may be advantageous for the development of new crossing combinations to improve root features in adzuki beans during the early growth stage. The root traits assessed in this study could be attributes for future adzuki bean crop selection and improvement. [ABSTRACT FROM AUTHOR]

The current unpredictable climate changes are causing frequent and severe droughts. Such circumstances emphasize the need to understand the response of plants to drought stress, especially in rice, one of the most important grain crops. Knowledge of the drought stress response components is especially important in plant roots, the major organ for the absorption of water and nutrients from the soil. Thus, this article reviews the root response to drought stress in rice. It is presented to provide readers with information of use for their own research and breeding program for tolerance to drought stress in rice. [ABSTRACT FROM AUTHOR]