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Analysis of Distribution of Root Length Density of Apple Trees on Different Dwarfing Rootstocks

Nondestructive evaluations of turfgrass root systems have been limited to large rhizotrons. Recent developments in the minirhizotron and associated microvideo camera technologies provide opportunities for quantifying in situ root systems of turfgrass field plots. Minirhizotron root counts were compared with destructive core sampling for root length and weight densities of ‘Penncross’ creeping bentgrass (Agrostis palustris Huds.) grown under putting green and fairway conditions, and annual bluegrass [Poa annua L. var. reptans (Hausskn.) Timm] grown under fairway conditions. Correlations between minirhizotron root counts and root length density (cm root/cm3 soil), minirhizotron root counts and root weight density (mg root/cm3 soil), and root weight density and root length density (r2 = 0.861, 0.843, and 0.955, respectively) were very highly significant when data were combined across all depth zones for an October sampling of the bentgrass green. Total root numbers observed along minirhizotrons were greatest early in the growing season, followed by a decline during July. Annual bluegrass root measurements were lower than either of the creeping bentgrass turfs. The root system of the creeping bentgrass turfs recovered during late summer, whereas the annual bluegrass turf showed little recovery from summer root decline. Data indicated that minirhizotron estimates provided an acceptable means for characterizing the profile distribution of turfgrass root systems from the soil surface to 300 mm, and possibly deeper into the soil profile.

干旱区棉田残膜污染日益严重, 秸秆覆盖能从根本上杜绝农田残膜增量。为探索秸秆覆盖代替塑料薄膜与滴灌结合的可行性, 需了解秸秆覆盖对滴灌棉田土壤水盐分布及棉花根系的影响特点, 同时探索耕作层以下30 cm处埋设一层秸秆进行深层秸秆覆盖与滴灌结合的效果。本文采用测坑试验研究了3种秸秆覆盖方式(表层覆盖、30 cm深层覆盖和无覆盖)与滴灌结合在2种土壤条件下(非盐碱土和盐碱土), 棉花根系分布稳定后的絮期土壤水盐运移及棉花根系分布特征。结果表明: 表层覆盖对于土壤整体保水性较好, 能有效抑制耕层水分散失和盐分聚集; 30 cm深层覆盖整体保水性优于无覆盖, 相对表层覆盖仅在秸秆层以下靠近滴灌带的有限范围内具有优势, 并显著提高耕层以下土壤水分含量, 但在棉花絮期对于盐分抑制作用不明显。秸秆覆盖通过对水盐运动的影响而显著影响棉花根系分布, 尤其对深层根系分布影响更大。非盐碱土条件下, 0~28 cm土层, 无覆盖处理根长密度、根重密度、根长密度比重均最大, 表层覆盖根长密度最小, 但根重比重最大, 30 cm深层覆盖根重密度最小; 在28~70 cm土层, 30 cm深层覆盖根长密度最大, 表层覆盖根长密度最小, 但根长密度比重最大, 无覆盖根长密度比重最小, 其中在28~56 cm土层30 cm深层覆盖根重密度和根重比重均最大。盐碱土条件下, 0~28 cm土层, 表层覆盖与30 cm深层覆盖根长密度和根长比重均高于无覆盖处理, 同时表层覆盖根重密度最高, 30 cm深层覆盖根重密度和根重比重均最低; 在28~70 cm土层情况相反, 30 cm深层覆盖处理根重比重最大, 但根重密度最小。说明表层覆盖可促进非盐碱土及盐碱土耕作层根系发育, 30 cm深层覆盖限制上层根系发育, 但促进30 cm以下土层根系发育, 在盐碱逆境下秸秆覆盖可促进根系向更细更长方面发育。秸秆覆盖与滴灌结合在干旱区具有良好应用前景。

Palm oil mill effluent (POME) sludge is a nutrient-rich organic byproduct with potential application in sustainable agriculture. However, limited information about POME sludge deserves serious attention since its application in agriculture could enhance plant growth and productivity. This study assesses the effects of raw POME sludge and alginate-encapsulated POME sludge as soil amendments on the growth and productivity of Brassica rapa subsp. chinensis L. A field experiment was conducted using a Completely Randomized Design with three treatments: control (no amendment), POME sludge, and POME sludge encapsulated with sodium alginate. Key agronomic parameters including plant height (cm), chlorophyll content (SPAD), leaf width (cm), shoot and root biomass, total yield (g), and shoot-to-root ratio were measured at biweekly intervals. Statistical analysis was performed using ANOVA and post-hoc least significant difference (LSD) tests at p < 0.05. The results indicated no significant differences in plant height, SPAD, or leaf width among these treatments. In contrast, yield, shoot biomass, and shoot-to-root ratio were significantly improved, with the highest values observed in the alginate-encapsulated POME sludge treatment. Yield increased from 154.00 g in the control to 340.16 g in the encapsulated treatment. Correlation analysis further supported strong associations between shoot biomass, yield, and shoot‑to-root ratio. The findings demonstrate that alginate-encapsulated POME sludge is an effective organic amendment for enhancing yield and biomass accumulation in Brassica rapa subsp. chinensis L. production.

Water transmission characteristics of a Vertisol and water use efficiency of rainfed soybean ( Glycine max (L.) Merr.) under subsoiling and manuring

Growing catch crops is one of the possible strategies to decrease erosion and nitrogen loss from soil profiles. Biomass yield and root system size have significant impacts on the soil nitrogen content. a three‑year field experiment with eight varieties of white mustard (Sinapis alba L.) was established to evaluate the effects of genotype and environment on biomass yield, soil nitrogen content and rooting parameters. Significant effects of genotype were found for root length density (RLD), root surface density (RSD) and specific root length (SRL) in the plow layer (0 – 20 cm) and for root system size (RSS), measured by electrical capacitance method, during three phenological phases. Higher biomass yield in varieties with higher RLD and RSD values during ripening and a larger RSS during flowering were found in dry conditions. Relationship of the root system and biomass yield to nitrate and ammonia nitrogen content varied in different environments. We found a significant relation between the RSS and ammonia nitrogen content in more fertile environment on average over the three years. The nitrate nitrogen content was related to the RLD, RSD and SRL in favorable year at shallow soil depths (0 – 20 cm).

Background and aims Benefits for soil health associated with crop rotations can improve plant aboveground biomass, although the effect on root traits is unclear. The aim of this study was to measure the legacy effect of crop rotations typical of dairy farms on root traits of subsequent forage corn (Zea mays L.) and soybean (Glycine max [L.] Merr.). Methods On a silty clay in eastern Canada, six rotations were compared, varying in crop species (perennials and/or annuals) and fertilizer sources (dairy cattle slurry and/or mineral fertilizer) for 5 years. Roots of subsequent corn and soybean were sampled by coring (0–45 cm), washed, and digitized for image analysis. Results Crop rotations including perennial crops rather than only annual crops resulted in greater total net annual productivity in corn (+ 20%) and soybean (+ 21%), corn root biomass (+ 31%) and length density (+ 106%), and proportion of fine roots. Compared to the alfalfa-grass mixture, grass-only mixtures resulted in a greater corn root biomass (+ 23%) and length density (+ 54%). A longer duration (5 vs. 3 years) of the alfalfa-grass mixture improved corn root length density (+ 37%) and corn and soybean fine root proportion at depth, suggesting benefits from maintaining perennial forage stands over time. Mineral fertilizer versus slurry improved root traits of subsequent corn and soybean when applied to perennial but not annual crops. Conclusion Our results highlight the positive response of corn and soybean root traits to the presence, species composition, and duration of perennial forage crops, extending further their benefits within rotations.

The allocation of resources among roots and shoots represents the largest flux of resources within a plant and therefore should have been selected to maximize benefits to plants. Yet, it is unclear why some species like temperate grasses have such high root length density (RLD). Either the slow rate of diffusion of inorganic N in soils or interplant competition could explain the high RLD of temperate grasses. Using a fine-scale model of nutrient dynamics in the soil and plant growth, a cost–benefit approach was used to assess optimal allocation rates for plants that accounted for value of both carbon and nitrogen. In the absence of interplant competition, resource benefits are maximized with very little root length except in extremely dry soils for ammonium. In the presence of a competitor, optimal allocation of N to roots is much greater and increases as ability of competitors to produce root length increase. Competition for inorganic nitrogen generates a classic aspect of the tragedy of the commons, the “race for fish”, where plants must allocate more resources to acquisition of the limiting resource than is optimal for plants in the absence of competition. As such, nutrient competition needs to be directly addressed when understanding plant- and ecosystem-level resource fluxes as well as the evolution of root systems.

Generalization of the root length density distribution of cotton under film mulched drip irrigation

Aim of study: The study was conducted to characterize the impacts of plant roots systems (e.g., root length density and root biomass) on soil preferential flow in forest ecosystems.Area of study: The study was carried out in Jiufeng National Forest Park, Beijing, China.Material and methods: The flow patterns were measured by field dye tracing experiments. Different species (Sophora japonica Linn, Platycladus orientalis Franco, Quercus dentata Thunb) were quantified in two replicates, and 12 soil depth were applied. Plant roots were sampled in the sieving methods. Root length density and root biomass were measured by WinRHIZO. Dye coverage was implied in the image analysis, and maximum depth of dye infiltration by direct measurement.Main results: Root length density and root biomass decreased with the increasing distance from soil surface, and root length density was 81.6% higher in preferential pathways than in soil matrix, and 66.7% for root biomass with respect to all experimental plots. Plant roots were densely distributed in the upper soil layers. Dye coverage was almost 100% in the upper 5-10 cm, but then decreased rapidly with soil depth. Root length density and root biomass were different from species: Platycladus orientalis Franco > Quercus dentata Thunb > Sophora japonica Linn.Research highlights: The results indicated that fine roots systems had strong effects on soil preferential flow, particularly root channels enhancing nutrition transport across soil profiles in forest dynamics.Key words: soil preferential flow; preferential pathways; soil matrix; root length density; root biomass.

Partial root-zone irrigation (PRI) has been practiced worldwide, but little information is available on nitrogen (N) supply methods influence on fate of applied N fertilizer for crop production under PRI. A field experiment was conducted to investigate effect of N supply methods on the uptake, residual, and loss of applied N fertilizer in maize (Zea mays L.) under alternate PRI at Wuwei, northwest China in 2014. 15N-labeled urea was used as N fertilizer. Two irrigation methods included alternate furrow irrigation (AI) and conventional furrow irrigation (CI). Two N fertilizer supply methods included conventional N supply (CN) and alternate N supply (AN), were applied in combination with each irrigation method. Grain yield, root length density (RLD), N uptake by maize at the maturity stage, and atom % of 15N excess, residual 15N and residual NO3-N in the 0-100 cm soil layer after maize harvest were determined. Results shown that compared to CI coupled with CN, AI coupled with AN or CN significantly increased the grain yield, harvest index, RLD, N uptake by maize, 15N accumulation in grain, atom % of 15N excess in the 0-60 cm soil layer, the residual 15N and 15N uptake rates; but significantly decreased the residual NO3-N in the 0-100 cm soil layers and 15N loss rate. Moreover, the synchronized rather than separation supply of N fertilizer and water enhanced the most above parameters under AI. 15N uptake rate was positively correlated with RLD in the 0-40 cm soil layer, suggesting that the enhanced RLD contributed to the improved 15N uptake rate. Therefore, alternate furrow irrigation coupled with conventional or alternate nitrogen supply (synchronized supply of N fertilizer and water) could help improve 15N uptake rate and reduce the 15N loss rate. Keywords: 15N-labeled technology, root length density, nitrogen fertilizer fate, nitrogen management, residual nitrogen DOI: 10.25165/j.ijabe.20201303.5287 Citation: Qi D L, Hu T T, Song X. Effects of nitrogen supply methods on fate of nitrogen in maize under alternate partial root-zone irrigation. Int J Agric & Biol Eng, 2020; 13(3): 129–135.

Sorghum root growth and water-use as affected by water supply and growth duration

The spatial distribution of root length density (RLD) is important for water and nutrient uptake by plants and biomass allocation in the soil. Experimental root assessment is, however, mostly based on methods that encompass only small fractions of the soil volume. The aim of this study was to characterize the three dimensional (3D) spatial distribution of RLD in the soil of a maize crop for plots of 37.5 and 75 cm row spacing. At each plot, a 3D soil monolith of 70 × 40 × 30 (=84,000) cm3 was completely sampled in form of 84 cubic samples of 10 cm edge length. Roots were washed from the soil and RLD was determined using the line intersect method. In 2004, mean RLD values were 0.41 cm cm−3 for narrow and 0.34 cm cm−3 for wide row spacing at row closure (55 days after planting; DAP) and 0.74 cm cm−3 (1.37 cm cm−3 in 2003) for narrow and 0.77 cm cm−3 (0.96 cm cm−3 in 2003) for wide row spacing at tasseling (104 DAP). The CV values for RLD of 48% to 72% in 2004 were first higher for wide than for narrow row spacing but at the later growth stage (tasseling) lower for wide than for narrow. For individual vertical soil slices, CV values for RLD were about 40–60%, irrespective of the orientation of the slice. The results suggest that RLD was related mainly to the spatial location and the plant row structure, and not governed unambiguously by SBD or SWC. The spatially distributed maize root data suggest that variability of RLD parallel to plant rows is not negligible. Any simplified use of 1D or 2D vertical samples at separate locations may lead to erroneous estimations of RLD profiles.

Fusarium root rot is a major limiting factor in snap bean ( Phaseolus vulgaris L.) production. The level of genetic resistance in commercial bean cultivars is minimal and disease is frequently exacerbated by environmental factors. We investigated the contribution of vigorous, adventitious roots to enhancing root rot tolerance in snap bean. Seedling root system architecture was evaluated in 17 recombinant inbred lines (RILs) from a cross of a resistant snap bean line (FR266) and a susceptible dry bean cultivar (Montcalm). The RILs varied in tolerance to Fusarium root rot. Although overall length and branching density (as measured by fractal dimension and meristem numbers) of root systems were not related to root rot resistance, the lateral root number at the root: shoot interface was positively correlated with genotype tolerance ( R 2 = 0.6 * ). Root diameter was also positively correlated with tolerance; this is consistent with the hypothesis that larger adventitious and basal roots are beneficial under disease stress. A field-based study of commercial snap bean cultivars compared raised and flat-bed systems of production, in a soil inoculated with Fusarium solani f. sp. phaseoli. Substantially greater yields (40% to 90%) were observed in raised beds. Root vigor was relatively high (root length density >0.2 cm·cm −3 ) and root rot scores were lower with raised than with flat-beds, in 2001, but not in 2000. Overall, this is suggestive that integrated crop management practices can improve lateral root vigor and reduce root rot severity.

The main objective of the experiment was to compare the phosphorus efficiency of three CIMMYT bred genotypes of wheat (‘ChilWuh’, ‘BauKauz’, and ‘PgoSeri’) with the old Mexican variety ‘Curinda’. These four strains of wheat genotypes were cultivated in the field (sandy clay, 3.7 ppm Olsen P, in Mexico) at two P levels (0 and 80 kg P2O5/ha). All four genotypes responded positively to P fertilization. In comparison with P-0, the yield of P-80 was 78 % higher. The three new genotypes ‘ChilWuh’, ‘BauKauz’, ‘PgoSeri’ showed significantly higher yields when compared with the old variety ‘Curinda’. The yield difference was 54 % at P-0 and 42 % at P-80. The higher yield was mainly due to a larger number of grains per ear, higher thousand grain weight (TGW) as well as a higher harvest index. The old variety ‘Curinda’ was superior with regard to the number of ears per unit area. As a result of this experiment, the new genotypes could be classified as P efficient. This high level of P efficiency is mainly due to a more effective P uptake, however, there was little change with respect to P utilisation between old and new varieties. The P uptake at harvest averaged 35 % and 24 % more as the old variety ‘Curinda’ at P-0 and P-80 respectively. These results show that at P-0 level, the morphology of the root system played a greater role when compared with conditions of higher P fertilization. Due to their higher root length density after flowering, the new varieties showed an improved P uptake even at P-0 fertilization levels, while at P-80, a higher P influx per unit root length played a more important role than root length density.