Phenology of fine roots and shoots using high frequency temporal resolution images in a temperate larch forest

Purpose Understanding tree phenology reveals the underlying mechanisms through plant functional and productive activities and carbon sinks in forest ecosystems. However, previous research on tree phenology has focused on shoot dynamics rather than tree root dynamics. We aimed to explore seasonal temperature patterns of daily-based root and shoot dynamics by capturing high frequency plant images in a larch forest. Methods We monitored continuous images using an automated digital camera for shoot dynamics and a flatbed scanner for the fine root dynamics in the larch. Using the images, we analyzed the relationship between temperature and plant area index as shoot growth status and total root-area proportion of white and brown roots. Results Larch shoot production had a single mountain-shaped peak with a positive correlation between plant area index and air temperature. Fine root production had two peaks in the bimodal root-growth pattern in early summer and late autumn. Soil temperature was positively correlated with white root proportion and negatively correlated with brown root proportion. Conclusion We found differences between shoots and roots regarding temperature relationships. In particular, the automated flatbed scanner method for the root dynamics allowed the collection of detailed bimodal patterns of root production with shift from whitening to browning color, which had been previously overlooked. Such high frequency temporal resolution analysis can provide an in-depth of mechanisms of fine-root and shoot phenology through different stages of plant development in terms of growth and senescence.

Spatial and Temporal Variation in Fine Root Biomass, Productivity and Turnover in Shorea Robusta Along the Gradient of Tree Girth Size

Fine roots (≤ 2 mm of diameter) contribute diminutive fractions of the overall tree biomass but are highly zestful and functionally remarkable component for assessing forest carbon and nutrient budgets. This study assessed how tree girth influenced fine root biomass (FRB), production (FRP) and turnover rate (FRT) in sub tropical sal forest.Four sites (S1, S2, S3, S4) were established in the bhabhar region of Nainital district, Uttarakhand, India within an elevational range of 405m and 580m. On the basis of girth size, sal trees were categorized in five girth size classes. Fine roots were sampled seasonally to a depth of 60 cm and divided into 3 layers (0-20, 20-40 and 40-60 cm).FRB was significantly affected by tree girth size (p< 0.05) while FRP and FRT showed insignificant effect. FRB was higher in lower girth classes (A-C) as compared to higher girth classes (D-E).Seasonal variation of FRB in all girth sizes showed a keen resemblance as the standing FRB reached pinnacle during rainy season and reached bottom-line in the winter season. Maximum FRB was reported for uppermost organo-mineralic soil depth (0-20 cm) at 1 m distance from tree bole and decreased with increasing soil depth and distance from tree bole while FRT showed a reverse trend. The present study will provide a holistic outlook on variations in FRB, FRP and FRT and the impact of edaphic characteristics and tree girth on fine root dynamics with respect to the studied forest stands.

Electrical Capacitance Versus Minirhizotron Technique: A Study of Root Dynamics in Wheat–Pea Intercrops

This study evaluated the concurrent application and the results of the root electrical capacitance (CR) and minirhizotron (MR) methods in the same plant populations. The container experiment involved three winter wheat cultivars, grown as sole crops or intercropped with winter pea under well-watered or drought-stressed conditions. The wheat root activity (characterized by CR) and the MR-based root length (RL) and root surface area (RSA) were monitored during the vegetation period, the flag leaf chlorophyll content was measured at flowering, and the wheat shoot dry mass (SDM) and grain yield (GY) were determined at maturity. CR, RL and RSA exhibited similar seasonal patterns with peaks around the flowering. The presence of pea reduced the maximum CR, RL and RSA. Drought significantly decreased CR, but increased the MR-based root size. Both intercropping and drought reduced wheat chlorophyll content, SDM and GY. The relative decrease caused by pea or drought in the maximum CR was proportional to the rate of change in SDM or GY. Significant linear correlations (R2: 0.77–0.97) were found between CR and RSA, with significantly smaller specific root capacitance (per unit RSA) for the drought-stress treatments. CR measurements tend to predict root function and the accompanying effect on above-ground production and grain yield. The parallel application of the two in situ methods improves the evaluation of root dynamics and plant responses.

Dynamics of the Potato Root (Solanum Spp.) Under Different Levels of Soil Moisture, in the Geographical Region of Riobamba, Ecuador

The root system of the potato (Solanum spp.) is often characterized as superficial and inefficient, with little capacity to extract water from the soil. Through a geographical study of the study area and root dynamics, the root behavior of the Victoria variety in Riobamba, Ecuador was evaluated, with the aim of assessing the applicability of “drip irrigation strategies with different levels of soil moisture” that allow the optimization of the water resource and the degree of tolerance of the crop to the lack of water through three treatments, 25%, 50% and 75%, between the levels of field capacity and permanent wilting point that are equivalent to 12.25% (T1), 10.5% (T2) and 8.75% (T3) of sandy loam soil moisture. Through front-wall rhizotrons the gravimetric method for recording soil moisture, and the Scheffé test, with a randomized block experimental design, were completed. The maximum root development was reached 110 days after the cultivation was established, with 77.5 cm (T3) at lower water availability. The maximum yield was reached at 132 days, with 34.72 t/ha (T1), followed by 32.11 t/ha (T2) with 126 days, and 28.45 t/ha (T3) with 121 days. Therefore, it is concluded that the maximum permissible humidity level for the variety is 10.5%, since lower levels would generate large losses. Keywords: rizotron, drip irrigation, soil moisture, geographical analysis. Resumen El sistema de raíces de la papa (Solanum spp.) a menudo se caracteriza por ser superficial e ineficiente, con poca capacidad para extraer agua del suelo. Mediante un estudio geográfico del área de estudio y la dinámica radicular se evalúa el comportamiento radicular de la variedad victoria en Riobamba-Ecuador, con el objetivo de valorar la aplicabilidad de estrategias de “riego por goteo con diferentes niveles de humedad en el suelo” que permitan la optimización del recurso hídrico y el grado de tolerancia del cultivo a la falta de agua mediante tres tratamientos 25%, 50% y 75% entre los niveles de capacidad de campo y punto de marchitez permanente que equivalen a 12,25%(T1), 10,5%(T2) y 8,75%(T3) de humedad del suelo franco arenoso. A través de rizotrones de pared frontal, el método gravimétrico para el registro de la humedad del suelo y la prueba de Scheffé, con un diseño experimental de bloques completos al azar. El máximo desarrollo radicular se alcanzó a los 110 días de establecido el cultivo con 77,5cm (T3) a una menor disponibilidad de agua. El rendimiento máximo se alcanzó a los 132 días con 34,72t/ha (T1), seguido de 32,11t/ha (T2) con 126 días y 28,45t/ha (T3) con 121 días. Por lo tanto, se concluye que el máximo nivel de humedad permisible para la variedad es 10,5%, ya que niveles inferiores generarían grandes pérdidas. Palabras claves: rizotrón, riego por goteo, humedad del suelo, análisis geográfico.

Multiple responses of fine root resource uptake strategies to gravel content in a subtropical plantation

Most forest soils contain substantial amounts of gravel. However, unlike the more widely known root resource uptake behaviors which respond to resource patches in substrate without gravels, how roots respond to substrate containing different gravel levels is poorly understood. We grew roots in substrates with five gravel levels (0, 10, 20, 30, and 40% of volume) in a subtropical Schima superba plantation, determined fine root dynamics and turnover rate with minirhizotrons, measured fine root morphological, architectural, mycorrhizal colonization, chemistry, and mass allocation. The presence of gravel in the substrate delayed the timing of peak root growth. In the substrate with higher gravel content, plants produced more in roots in autumn, but there were fewer roots in summer and the roots tended to exhibit lower fine root turnover rate and mycorrhizal colonization, but higher root biomass allocation. The higher root biomass in the substrate with higher gravel content was associated with higher root carbon/nitrogen ratio. Our findings emphasize the complexity of root resource uptake behavior in response to gravel content and suggest that incorporating substrate gravel content into root studies may help to improve the prediction of patch exploitation and nutrient acquisition in stony soils.