Evaluation of traits related to bread wheat (Triticum aestivum L.) root in drought tolerance applied at the beginning of vegetative and reproductive stages

<p class="042abstractstekst">Roots play an important role in wheat grain yield, especially under drought stress conditions. To investigate root characteristics under drought stress conditions in bread wheat, 90 lines F10 obtained from the crossing (‘Yecora Rojo’ × ‘Chinese Spring’) randomly with the parents of the population were examined. The study was conducted in the form of a split-plot design with a randomized complete block base in three conditions including: 1. no stress, 2. application of drought stress at the beginning of the vegetative stage, and 3. application of drought stress at the beginning of the reproductive stage. The results showed, interaction between genotype and condition of drought was significant for all root-related traits, except shallow root dry mass, at the level of 1 % probability. The response of root-related traits to different types of drought stress was very complex. The longest root length, decrease for 13.3 % was during stress at the beginning of the vegetative stage in comparison to non-stress conditions, while the same trait increased for 4.9 % during stress at the beginning of the reproductive stage, comparison to non-stress conditions. The results of principal component analysis under non-stress conditions showed that by considering the distribution of genotypes compared to the first two components, genotypes can be identified that have more yield with the proper root condition and vice versa.</p>

Improvement of Root Characteristics Due to Nitrogen, Phosphorus, and Potassium Interactions Increases Rice (Oryza sativa L.) Yield and Nitrogen Use Efficiency

Although nitrogen (N), phosphorus (P), and potassium (K) co-application improves crop growth, yield, and N use efficiency (NUE) of rice, few studies have investigated the mechanisms underlying these interactions. To investigate root morphological and physiological characteristics and determine yield and nitrogen use parameters, rhizo-box experiments were performed on rice using six treatments (no fertilizer, PK, N, NK, NP, and NPK) and plants were harvested at maturity. The aboveground biomass at the elongating stage and grain yield at maturity for NPK treatment were higher than the sum of PK and N treatments. N, P, and K interactions enhanced grain yield due to an increase in agronomic N use efficiency (NAE). The co-application of N, P, and K improved N uptake and N recovery efficiency, exceeding the decreases in physiological and internal NUE and thereby improving NAE. Increases in root length and biomass, N uptake per unit root length/root biomass, root oxidation activity, total roots absorption area, and roots active absorption area at the elongating stage improved N uptake via N, P, and K interactions. The higher total N uptake from N, P, and K interactions was due to improved root characteristics, which enhanced the rice yield and NUE.

Oilseed Rape Cultivars Show Diversity of Root Morphologies with the Potential for Better Capture of Nitrogen

The worldwide demand for vegetable oils is rising. Oilseed rape (Brassica napus) diversifies cereal dominated crop rotations but requires important nitrogen input. Yet, the root organ is offering an untapped opportunity to improve the nitrogen capture in soil. This study evaluates three culture systems in controlled environment, to observe root morphology and to identify root attributes for superior biomass production and nitrogen use. The phenotypic diversity in a panel of 55 modern winter oilseed rape cultivars was screened in response to two divergent nitrate supplies. Upon in vitro and hydroponic cultures, a large variability for root morphologies was observed. Root biomass and morphological traits positively correlated with shoot biomass or leaf area. The activities of high-affinity nitrate transport systems correlated negatively with the leaf area, while the combined high- and low-affinity systems positively with the total root length. The X-ray computed tomography permitted to visualize the root system in pipes filled with soil. The in vitro root phenotype at germination stage was indicative of lateral root deployment in soil-grown plants. This study highlights great genetic potential in oilseed rape, which could be manipulated to optimize crop root characteristics and nitrogen capture with substantial implications for agricultural production.

Genetic Dissection of Mature Root Characteristics by Genome-Wide Association Studies in Rapeseed (Brassica napus L.)

Roots are complicated quantitative characteristics that play an essential role in absorbing water and nutrients. To uncover the genetic variations for root-related traits in rapeseed, twelve mature root traits of a Brassica napus association panel were investigated in the field within three environments. All traits showed significant phenotypic variation among genotypes, with heritabilities ranging from 55.18% to 79.68%. Genome-wide association studies (GWAS) using 20,131 SNPs discovered 172 marker-trait associations, including 103 significant SNPs (−log10 (p) > 4.30) that explained 5.24–20.31% of the phenotypic variance. With the linkage disequilibrium r2 > 0.2, these significant associations were binned into 40 quantitative trait loci (QTL) clusters. Among them, 14 important QTL clusters were discovered in two environments and/or with phenotypic contributions greater than 10%. By analyzing the genomic regions within 100 kb upstream and downstream of the peak SNPs within the 14 loci, 334 annotated genes were found. Among these, 32 genes were potentially associated with root development according to their expression analysis. Furthermore, the protein interaction network using the 334 annotated genes gave nine genes involved in a substantial number of interactions, including a key gene associated with root development, BnaC09g36350D. This research provides the groundwork for deciphering B. napus’ genetic variations and improving its root system architecture.

Raising Climate-Resilient Embolden Rice (Oryza sativa L.) Seedlings during the Cool Season through Various Types of Nursery Bed Management

Facing cold stress is amajor constraint in seedling production during the winter season as, most particularly in recent times due to uncertain climatic conditions, no sustainable technology has been reported that could be easily adopted by farmers withlimited resources. Therefore, field experiments were carried out during winter 2017–2018 and 2018–2019 at the Central Research Farm of Bidhan Chandra KrishiViswavidyalaya, West Bengal, India to study the growth, survival potential, yield and nutritional and biochemical properties of boro rice seedlings as influenced by two seedbed management practices viz. conventional seedbed (farmers’ practice) and improved seedbed (polythene protected with micronutrient supplementation). The major objective was to lower the nurserybed duration without compromising seedlings’ health and to studythe economic viability during the winter season. The experiment was laid out in ten experimental units and deployed anindependent-sample t-test to compare the performance of the seedlings. The microclimatic changes were also itemized from both seedbeds. The seeds sownunder improved nursery conditions resulted in better seedling emergence (~90%) and survival percentage (~85%) as compared to the conventional seedbed (~70% and 65%). Growth attributes in terms of plant height, biomass accumulation, root characteristics, tiller count, and growth rate were observed to be better from the polythene-protected nursery bed. Theimproved nursery bed accounted for 20% higher seedling count at the time of transplantation over the conventional bed. The microclimatic situation under a polythene covering was also favorable for germination and seedling growth. Maximum nutrient (N, P, and K) concentrations, as well as chlorophyll content, wererecorded from improved seedlings. Results suggested that the improved seedbed management was apotential alternative toearly embolden seedling production during the winter to avoid climatic abnormalities. Most importantly, improved seedbeds ensured a comprehensive route from germination to healthy seedling production without any failure in thesmalltime window, which involvedless input as well as cost involvement. This technique could diffusethe problem oflate sowing conditions in the rice–rice cropping system.