Dry Matter Dynamics Research Articles

Post-anthesis dry matter dynamics in the internodes of wheat cultivars grown under contrasting conditions: associations among agro-physiological traits

Post-anthesis dry matter dynamics in the internodes of wheat cultivars grown under contrasting conditions: associations among agro-physiological traits

Ground Cover Rice Production System Affects Soil Water, Nitrogen Dynamics and Crop Growth Differentially with or without Climate Stress.

The ground cover rice production system (GCRPS) has been proposed as a potential solution to alleviate seasonal drought and early low-temperature stress in hilly mountainous areas; clarifying its impact on crop growth is crucial to enhance rice productivity in these areas. A two-year (2021-2022) field experiment was conducted in the hilly mountains of southwest China to compare the effects of the traditional flooding paddy (Paddy) and GCRPS under three different nitrogen (N) management practices (N1, zero-N fertilizer; N2, 135 kg N ha-1 as a urea-based fertilizer; and N3, 135 kg N ha-1 with a 3:2 base-topdressing ratio as urea fertilizer for the Paddy or a 1:1 basal application ratio as urea and manure for GCRPS) on soil water storage, soil mineral N content and crop growth parameters, including plant height, tiller numbers, the leaf area index (LAI), aboveground dry matter (DM) dynamics and crop yield. The results showed that there was a significant difference in rainfall between the two growth periods, with 906 mm and 291 mm in 2021 and 2022, respectively. While GCRPS did not significantly affect soil water storage, soil mineral N content, and plant height, it led to a reduction in partial tiller numbers (1.1% to 31.6%), LAI (0.6% to 20.4%), DM (4.4% to 18.8%), and crop yield (7.4% to 22.0%) in 2021 (wet year) compared to the Paddy. However, in 2022 (dry year), GCRPS led to an increase in tiller numbers (13.7% to 115.4%), LAI (17.3% to 81.0%), DM (9.0% to 62.6%), and crop yield (2.9% to 9.2%) compared to the Paddy. Structural equation modeling indicated that GCRPS significantly affected tiller numbers, plant height, LAI, DM, and productive tiller numbers, which indirectly influenced crop yield by significantly affecting tiller numbers and productive tiller numbers in 2022. Overall, the effects of GCRPS on soil water and N dynamics were not significant. In 2021, with high rainfall, no drought, and no early, low-temperature stress, the GCRPS suppressed crop growth and reduced yield, while in 2022, with drought and early low-temperature stress and low rainfall, the GCRPS promoted crop growth and increased yield, with tiller numbers and productive tiller numbers being the key factors affecting crop yield.

Fodder Galega—Persistence as a Special Asset in Sustainable Agriculture

Perennial crops, especially legumes, have a crucial role in the development of sustainable agriculture. One such species may be fodder galega (Galega orientalis Lam.), whose utility values, including persistence and multi-directional use, are still not sufficiently known and appreciated. The aim of this study was to evaluate fodder galega yield dynamics, taking into account some indices of fodder value and the accumulation of mineral components in long-term use in light soil under moderate climate conditions with periodic shortages of precipitation. The results of six long-term experiments conducted at the Mochełek Research Station (53°120′ N, 17°510′ E) were evaluated. The dynamics of dry matter, total protein yield, and accumulation of minerals were best reflected by trend lines in the form of logarithmic functions, where during the first 4–5 years of use, a significant increase in the assessed values was noted, and in subsequent years, the increase continued but at a lower rate. The advancement in plant development in the establishment year had a significant impact on yields in the first production year. On average, during 10 production years, the dry matter yield obtained was 936 g m2, and the total protein yield was 177 g m2. Between 50% and 60% of the yield was determined by herbage accumulation in the first cut. Among minerals, the highest accumulation level was achieved for potassium. The height of shoots and the content of crude fiber in the plants increased linearly in the following years. The shoot density, leafiness, and content of minerals did not depend on the age of the galega stand, and their values were different among growth periods within a season. The number of shoots per 1 m2 in successive cuts was 170, 139, and 92, and their height was 79, 67, and 31 cm, respectively. The share of leaves in the first cut yield was 50%, and in the second and third cuts, it was 65% on average. In these conditions, over 10 years of use, galega turned out to be a valuable, persistent, and reliably yielding fodder crop.

Dry matter dynamics and carbon flux along riverine forests of Gori valley, Western Himalaya

IntroductionRiverine forests in the Himalaya represent a biodiverse, dynamic, and complex ecosystem that offers numerous ecosystem services to local and downstream communities and also contributes to the regional carbon cycle. However, these forests have not been assessed for their contribution to dry matter dynamics and carbon flux. We studied these parameters along three classes of riverine forests in eastern Uttarakhand, dominated by Macaranga, Alnus, and Quercus-Machilus forest.MethodsUsing volume equations, we assessed tree biomass, carbon storage, and sequestration in the study area.ResultsThe total standing tree biomass in Macaranga, Alnus, and Quercus-Machilus forest ranged from 256.6 to 558.1 Mg ha−1, 460.7 to 485.8 Mg ha−1, and 508.6 to 692.1 Mg ha−1, respectively. A total of 77.6–79.6% of vegetation biomass was stored in the aboveground biomass and 20.4–22.4% in belowground plant parts across the riverine forests. The carbon stock in Macaranga forest ranged from 115.5 to 251.1 Mg ha−1, in Alnus forest from 207.3 to 218.6 Mg ha−1, and in Quercus-Machilus forest from 228.9 to 311.4 Mg ha−1. The mean annual litterfall was accounted maximum for Quercus-Machilus forest (5.94 ± 0.54 Mg ha−1 yr.−1), followed by Alnus (5.57 ± 0.31 Mg ha−1 yr.−1) and Macaranga forest (4.67 ± 0.39 Mg ha−1 yr.−1). The highest value of litterfall was recorded during summer (3.40 ± 0.01 Mg ha−1 yr.−1) and the lowest in winter (0.74 ± 0.01 Mg ha−1 yr.−1). The mean value of net primary productivity and carbon sequestration was estimated to be highest in Quercus-Machilus forest (15.8 ± 0.9 Mg ha−1 yr.−1 and 7.1 ± 0.9 Mg C ha−1 yr.−1, respectively) and lowest in Alnus forest (13.9 ± 0.3 Mg ha−1 yr.−1 and 6.1 ± 0.3 Mg C ha−1 yr.−1, respectively).DiscussionThe results highlight that riverine forests play a critical role in providing a large sink for atmospheric CO2. To improve sustainable ecosystem services and climate change mitigation, riverine forests must be effectively managed and conserved in the region.

Dynamics of Structural Dry Matter, Water Soluble Carbohydrates and Leaf Senescence Mediate the Response of Winter Wheat Yield to Soil Cover and Water Availability

Plastic film mulching often increases the yield of winter wheat in the Loess Plateau of China, but the physiological mechanisms are unclear, especially in response to the interaction between mulch and water supply. In this study, we investigated the interactive effects of initial soil water (dry, moderate, and wet), soil cover (plastic mulch, bare soil), and seasonal conditions on the dynamics of dry matter partitioning, water-soluble carbohydrates (WSC), and flag leaf senescence, and their relations with yield and its components. Plastic mulch increased dry matter accumulation at anthesis and maturity relative to bare soil, with no interaction with season or initial soil water. Allocation of dry matter to leaf, stem, and spike did not change with soil cover. Compared with bare soil, mulch increased WSC accumulation by 14% at anthesis and its translocation by 16%. Soil cover did not influence the senescence of flag leaf after anthesis as indicated by similar dynamics of the C:N ratio. Grain yield was higher under plastic mulch than bare soil in two out of three seasons, and was associated with a higher translocation amount of WSC and post-anthesis dry matter that linked grain weight, grain number, and harvest index.

Features of the soybean photosynthetic productivity indicators formation depending on the foliar nutrition

The three-year research findings prove that foliar nutrition with trace elements influences the dynamics ofleaf surface formation, dry matter accumulation, and soybean photosynthetic net productivity under theWestern Forest-Steppe conditions of Ukraine. It was found out that foliar nutrition with the particular traceelements could enlarge the soybean leaf surface area, chlorophyll content and dry matter yield. During theexperimental studies, a positive effect on increasing the leaf surface area in soybean crops during the end offlowering was found in the variants where copper, iron and molybdenum-containing fertilizer were applied.The leaf surface area in the variant where copper was applied reached 46.3 thousand m-2 ha, which confirmsthe importance of copper in the formation of sugars and protein, direct participation in the process ofphotosynthesis. On the basis of the conducted researches it is established that in general on the amount ofchlorophyll in soybean leaves foliar feeding has a significant effect. The average chlorophyll content insoybean leaves was 1.10 mg-2 g of raw weight. The dynamics of dry matter by phases of growth anddevelopment of soybeans is established. Soybean produced the maximum amount of dry matter duringgrain ripening. Thus, 7.59 t-1 ha of dry matter was formed during the control.

Dry matter dynamics and CO2 mitigation in the herb layer of Central Himalayan agroecosystems along an altitudinal gradient, India

Dry matter dynamics and CO2 mitigation in the herb layer of Central Himalayan agroecosystems along an altitudinal gradient, India

Structure and functioning of Coriaria nepalensis dominated shrublands in degraded hills of Kumaun Himalaya. I. Dry matter dynamics

AbstractIn Kumaun Himalaya, the shrublands dominated by Coriaria nepalensis are present in patches and due to their facilitative nature enhance the restoration of degraded hills. This study deals with the dry matter dynamics of C. nepalensis shrublands. The equation for C. nepalensis was developed to measure the biomass and to understand the dry matter dynamics through compartmental models. Total biomass of tree, shrub and herb varied from 71.66 to 217.40 t ha−1, 43.65 to 77.55 t ha−1 and 11.11 to 64.55 t ha−1, respectively. The biomass of herbs was higher during monsoon and lowest during the summer season. Litter fall varied from 1.02–1.70 t ha−1 yr−1 and the highest value of litter fall was recorded during winter (52%) followed by rainy (29%) and summer season (19%). Order of contribution of different components to total litter fall was: foliage (45.32%–50.33%) > twigs (36.80%–42.22%) > miscellaneous litter (4.62%–6.97%) > Bark (3.56%–5.47%) > reproductive parts (2.13%–3.57%). Shrub floor biomass was recorded maximum during the rainy season (11.32–37.55 t ha−1) followed by the winter season (13.03–25.36 t ha−1) and minimum in the summer season (6.83–12.80 t ha−1). Net primary productivity in trees, shrubs and sapling was ranged from 0.94 to 11.01, 1.83 to 4.88 and 0.55 to 0.87, respectively. Due to less canopy cover, the litter fall was less than from the majority of the forest types of the region. Thus, proper conservation and management measures must be designed to improve the structural components and functional traits of the shrubland ecosystem to enhance the ecological services on sustained basis.

Sugarcane replaced by cactus cladodes improves the ruminal dynamics of sheep

We evaluated the effect of the sugarcane replacement (Saccharum officinarum L.) by cactus cladodes (Nopalea cochenillifera Salm-Dyck) at different levels (0, 180, 360, 540 and 720 g kg-1 on a dry matter (DM) basis) in the diet of sheep on nutrient intake and digestibility, ingestive behaviour, microbial protein synthesis, nitrogen and water balance, dry matter and fibre dynamics and ruminal parameters in sheep. Five castrated male crossbred sheep, with an initial average body weight (BW) of 63.38 ± 7.70 kg, were allocated in a 5 × 5 Latin square design. The intakes of DM (P < 0.001), crude protein (CP) (P = 0.009), neutral detergent fibre content adjusted for ash and nitrogen compounds (NDFcp) (P = 0.0016), non-fibre carbohydrates (NFC) (P < 0.001), indigestible NDF (iNDF) (P = 0.0018) and total digestible nutrients (TDN) (P < 0.001) showed a quadratic effect, and the replacement levels on DM did not affect nutrient digestibility. Rumination (P = 0.001) and idle (P = 0.001) times decreased with increasing levels of cactus cladodes. Plasma urea nitrogen (PUN) (P = 0.039) increased, and there was no effect on microbial nitrogen synthesis and microbial efficiency. The pools of DM (P = 0.037), NDF (P = 0.008) and indigestible NDF (iNDF) (P = 0.010) were reduced with increasing replacement levels. The DM ingestive (P = 0.005) and degradation (P = 0.005) rates increased, and the passage rate (P = 0.049) showed a quadratic response, with a maximum value of 0.035 h-1 estimated for 44% replacement. Intake (P = 0.004), degradation (P = 0.006) and passage (P = 0.016) rates of NDF, as well as the iNDF passage rate (P = 0.014), increased. The ruminal pH (P = 0.012) reduced with increasing replacement levels. Ruminal ammonia nitrogen (NH3-N) (P = 0.020) showed a quadratic response over time, presenting an estimated maximum value of 17.9 mg dL-1 at 0.68 h after feeding. Regarding volatile fatty acids, there was an increase for acetate (P < 0.001), whereas propionate was not influenced. The butyrate (P < 0.001) concentration demonstrated a quadratic effect, with a maximum value of 14.1 mmol L-1. Replacing up to 440 g kg-1 DM of sugarcane by cactus cladodes is recommended to maximise ruminal dynamics and parameters and to improve nutrient use in sheep.

Safflower assimilate remobilization, yield, and oil content in response to nitrogen availability, sowing time, and genotype

In rainfed cropping systems, crops are typically subjected to terminal stresses, which diminish the assimilation process. Information regarding safflower (Carthamus tinctorius L.) dry matter dynamics during the seed-filling period and its association with yield-forming components is lacking. Field experiments over two years were conducted to assess the influence of nitrogen (N) fertilization levels (0, 100 and 200 kg ha−1), sowing time (autumn vs. spring) and genotype (two hybrids and an open-pollinated variety) on growth, assimilate remobilization, achene- and oil yield of safflower, and to identify early crop attributes as predictors of yield. Greater than 100 kg N ha-1 were required to optimize achene yield (> 4 Mg ha-1). On average, N promoted early growth and increased capitula and achenes per unit area compared with the non-fertilized control. The higher the availability of assimilates at the source, the greater their remobilization to sink (r = 0.823, P < 0.01), which was in turn associated with achene yield (r = 0.53, P < 0.05), provided that a critical sink size (number of achenes) had been established during flowering. Dry matter remobilization efficiency ranged between 29.5 % and 39.1 %. Under favorable conditions, hybrids exhibited higher achene- and oil yield than the variety. Oil yield was almost entirely (98 %) determined by achene yield. Autumn sowing increased the average achene yield (28 %) and oil production (20 %) compared with spring sowing. Harvest index (HI) ranged from 0.17 to 0.35 and was associated with achene yield (r = 0.703, P < 0.01). Achene yield could be predicted by measurements of dry matter at anthesis, while the estimation of biomass from plant height measurements was not applicable in safflower. Findings highlight the value of properly designed cropping systems for safflower production based on environmental variables and crop management practices, which can support high yields and improve N management.

Microbial succession and changes in carbon and nitrogen during decomposition of leaf litters of Tephrosia candida (Roxb.) DC. and Oryza sativa L. under shifting cultivation in Mizoram, northeast India

The present study aims to understand microbial succession and dynamics of dry matter, carbon and nitrogen during the decomposition of leaf litters of Tephrosia candida (Roxb.) DC. and Oryza sativa L. in two fallow lands (FL) of 3 years (FL-3) and 8 years (FL-8) following shifting cultivation in Mizoram. A total of 64 microorganisms were isolated from two leaf litters by serial dilution method, out of which 13 microbes were identified as decomposers as they exhibited a positive response towards the enzyme activity. Among these 13 microorganisms, 4 (SKT 02, SKT 05, SKT 09 and SKT 020) were bacteria (Streptobacillus sp. and Bacillus sp.), 5 (SKT 033, SKT 034, SKT 035, SKT 040 and SKT045) were fungi (Microsporum sp., Rhizopus sp. and Aspergillus sp.) and 4 (SKT 030, SKT 052, SKT 053 and SKT 060) were actinomycetes (Streptomycetes sp.). T. candida leaf litter possessed low initial Carbon/Nitrogen (8.77) and Lignin/Nitrogen ratio (2.29) and considered a high-quality resource exhibiting higher decomposition rate. Mass loss of carbon and nitrogen (~ 40-80%) was maximum during the initial two months, which slowed down in the later period of decomposition. It was concluded that the number of bacteria, fungi and actinomycetes regulate organic matter and nutrient dynamics in the soil through various enzymatic actions on high- and low-quality litters. The combination of O. sativa and T. candida litter is recommended to manage soil fertility in shifting cultivation of Mizoram,Northeast India.

The effect of different sowing dates on dry matter and nitrogen dynamics for winter wheat: an experimental simulation study.

BackgroundTimely sowing is an important agronomic measure to ensure the normal germination, stable seedling establishment, and yield formation for winter wheat (Triticum aestivum L.). Delayed sowing frequently occurs in the current multi-cropping system and mechanized production of this crop. However, the ways in which different sowing dates affect yield and its potential mechanism is still unknown in the middle-lower Yangtze River Basin. We sought to provide a theoretical basis for these mechanisms to improve regional wheat production.MethodsWe investigated the wheat’s yield differences in a two-year field study under different sowing dates and took into account related growth characteristics including meteorological conditions, growth period, tillers, dry matter accumulation (DMA), and nitrogen accumulation (NA). We used the logistic curve model to simulate DMA and NA dynamics of single stem wheat under different sowing dates. We then analyzed and compared wheat accumulation for different sowing dates.ResultsOur results showed that grain yield declined by 0.97 ± 0.22% with each one-day change (either early or delayed) in sowing beyond the normal sowing date. The yield loss could be explained by the inhibition of crop growth, yield components, biomass and nitrogen (N) production. The negative effects of delayed sowing were caused by environmental limitations including adverse weather factors such as low temperature during vegetative growth, shortened duration of various phases of crop development, and increased temperature during the grain-filling period. The grain yield gap decreased between the late and normal sowing periods owing to a compensatory effect between the highest average rates (Vt) and the rapid accumulation period (T) of DMA and NA for single stem wheat. The grain yield was maintained at 6,000 kg ha−1 or more when the ratio of DMA at the mature-to-jointing stage (MD/JD) and the ratio of NA at the mature-to-jointing stage (MN/JN) was 4.06 (P < 0.01) and 2.49 (P < 0.05), respectively. The compensatory effect did not prevent the impact caused by delayed sowing, which caused biomass and N production to decrease. Physiological development reached a maximal accumulation rate (Tm) of NA earlier than DMA.

Developing perennial fruit crop models in APSIM Next Generation using grapevine as an example

AbstractA new model for grapevines (Vitis vinifera) is the first perennial fruit crop model using the Agricultural Production System sIMulator (APSIM) Next Generation framework. Modules for phenology, light interception, carbohydrate allocation, yield formation and berry composition were adapted or added into APSIM Next Generation to represent the nature of fruit-bearing vines. The simulated grapevine phenological cycle starts with the dormancy phase triggered by a critical photoperiod in autumn, and then goes through the subsequent phenophases sequentially and finally returns to dormancy for a new cycle. The canopy microclimate module within APSIM Next Generation was extended to allow for row crop light interception. The carbohydrate arbitrator was enhanced to consider both sink strength and sink priority to reflect carbohydrate reserve as a concurrent competing sink. Weather conditions and source–sink ratio at critical developmental stages were used to determine potential grapevine yield components, e.g. bunch number, berry number and berry fresh weight. The model was calibrated and tested extensively using four detailed data sets. The model captured the variations in the timing of measured budburst, flowering and véraison over 15 seasons across New Zealand for five different varieties. The calculated seasonal dynamics of light interception by the row and alley were consistent with field observations. The model also reproduced the dynamics of dry matter and carbohydrate reserve of different organs, and the wide variation in yield components caused by seasonal weather conditions and pruning regimes. The modelling framework developed in this work can also be used for other perennial fruit crops.

Uncovering novel phase transitions in dense dry polar active fluids using a lattice Boltzmann method

The dynamics of dry active matter have implications for a diverse collection of biological phenomena spanning a range of length and time scales, such as animal flocking, cell tissue dynamics, and swarming of inserts and bacteria. Uniting these systems are a common set of symmetries and conservation laws, defining dry active fluids as a class of physical system. Many interesting behaviours have been observed at high densities, which remain difficult to simulate due to the computational demand. Here, we show how two-dimensional dry active fluids in a dense regime can be studied using a simple modification of the lattice Boltzmann method. We apply our method on a model that exhibits motility-induced phase separation, and an active model with contact inhibition of locomotion, which has relevance to collective cell migration. For the latter, we uncover multiple novel phase transitions: two first-order and one potentially critical. We further support our simulation results with an analytical treatment of the hydrodynamic equations obtained via a Chapman–Enskog coarse-graining procedure.

Site quality and vegetation biomass in the tropical Sal mixed deciduous forest of Central India

Tropical Sal forests are gaining wide recognitions due to its multifarious significance. An estimation of vegetational structure and biomass would be helpful for evaluating both productivity and sustainability of the forest ecosystems. Information regarding vegetational biomass, litter mass and fine root biomass, and overall dry matter dynamics are very limited. Therefore, the present work deals the vegetation biomass influenced by four different site quality of Sal dominating tropical deciduous forest of Chhattisgarh, India. The current study provides a framework under which all vegetational attributes can be quantified under varying site quality which is modified by different seasons. Our study revealed a significant increase in vegetational attributes and biomass as per increasing quality of sites. The density value (individuals/ha) and basal area (m2/ha) of tree, sapling and seedling in different sites were ranged from 710 to 1010, 2000 to 2500, 9750 to 14,500 and 33.5 to 46.8, 0.32 to 0.33, 17.96 to 21.43, respectively. The total biomass varied from 187.39 to 383.46 t ha−1. The fine root and forest floor biomass varied between 2.44 and 4.20 t ha−1, and 2.32 and 2.83 t ha−1, respectively among different sites and seasons. The total litter fall varied from 4.18 to 5.69 t ha−1 yr−1 across the site quality. It reflected that highest value of forest floor, litter floor and fine root biomass were seen in site quality (SQ) SQ-I followed by SQ-II, SQ-III and SQ-IV, respectively in different seasons. A great synergy exists among site quality, stand structure and biomass which surely affect ecosystem structure and its functions. Seasonal impacts are another factor that regulates vegetational statistics, forest floor, fine roots and pattern of litterfall in varying site qualities. Thus, a management implication is needed to understand site quality variation which entirely affects vegetational structure and biomass pattern that would help in strengthening sustainable forest management program.

Restrictive irrigation improves yield and reduces risk for faba bean across the Middle East and North Africa: A modeling study

CONTEXTFaba bean is a crucial component of Mediterranean food systems. However, the crop is somewhat underrepresented in the major crop models and usage of these models requires substantial calibration with data that might not be available. The Simple Simulation Model (SSM) is a simple, non-calibrated and physiology-based model that has the advantage of having a reduced number of parameters that can all be measured or inferred from simple experiments. OBJECTIVEWe aimed to parameterize and assess the capacity of the SSM to simulate faba bean phenology, dry matter accumulation, nitrogen accumulation and final yield and to explore the impact of supplemental irrigation on crop production. MATERIALS & METHODSModel simulations were compared to observations collected over 30 experimental situations in Morocco, Tunisia, and Lebanon. SSM was then used to explore water restrictive irrigation scenarios, allowing two irrigation events after flowering, with a total irrigation dose of 50 mm, in the Middle East and in North Africa (MENA). RESULTS AND CONCLUSIONSThe prediction error on final total above ground dry matter was satisfactory and the dynamics of dry matter and nitrogen accumulation in plant organs matched the observations. This study showed that 50 mm irrigation can be sufficient to substantially improve faba bean production sustainability in MENA. In the driest areas (below 200 mm in-season rainfall), 50 mm irrigation could reduce the risk of low crops by up to 34% and increase yield sufficiently to meet average farm household needs. In more humid areas of the region, 50 mm irrigation could improve faba bean yield by up to 1 t/ha compared to an average yield of 3.5 t/ha. Simulation outputs showed that deficit irrigation could improve N soil balance and soil health in the mid- to long-term. The analysis of the simulation results can be used to advise farmers on best adapted irrigation dates without additional in situ measurement. SIGNIFICANCEThis study revealed that non-calibrated models such as SSM can simulate yield and dry matter accumulation with a predictive capacity similar to calibrated tools making it suitable for addressing a known gap in irrigation management for Mediterranean food systems. In the MENA region, relative small amounts of irrigation (50 mm) can substantially reduce production risk, and so increase security for farmers, and improve faba bean productivity and sustainability.

Mapping Wheat Dry Matter and Nitrogen Content Dynamics and Estimation of Wheat Yield Using UAV Multispectral Imagery Machine Learning and a Variety-Based Approach: Case Study of Morocco

Our work aims to monitor wheat crop using a variety-based approach by taking into consideration four different phenological stages of wheat crop development. In addition to highlighting the contribution of Red-Edge vegetation indices in mapping wheat dry matter and nitrogen content dynamics, as well as using Random Forest regressor in the estimation of wheat yield, dry matter and nitrogen uptake relying on UAV (Unmanned Aerial Vehicle) multispectral imagery. The study was conducted on an experimental platform with 12 wheat varieties located in Sidi Slimane (Morocco). Several flight missions were conducted using eBee UAV with MultiSpec4C camera according to phenological growth stages of wheat. The proposed methodology is subdivided into two approaches, the first aims to find the most suitable vegetation index for wheat’s biophysical parameters estimation and the second to establish a global model regardless of the varieties to estimate the biophysical parameters of wheat: Dry matter and nitrogen uptake. The two approaches were conducted according to six main steps: (1) UAV flight missions and in-situ data acquisition during four phenological stages of wheat development, (2) Processing of UAV multispectral images which enabled us to elaborate the vegetation indices maps (RTVI, MTVI2, NDVI, NDRE, GNDVI, GNDRE, SR-RE et SR-NIR), (3) Automatic extraction of plots by Object-based image analysis approach and creating a spatial database combining the spectral information and wheat’s biophysical parameters, (4) Monitoring wheat growth by generating dry biomass and wheat’s nitrogen uptake model using exponential, polynomial and linear regression for each variety this step resumes the varietal approach, (5) Engendering a global model employing both linear regression and Random Forest technique, (6) Wheat yield estimation. The proposed method has allowed to predict from 1 up to 21% difference between actual and estimated yield when using both RTVI index and Random Forest technique as well as mapping wheat’s dry biomass and nitrogen uptake along with the nitrogen nutrition index (NNI) and therefore facilitate a careful monitoring of the health and the growth of wheat crop. Nevertheless, some wheat varieties have shown a significant difference in yield between 2.6 and 3.3 t/ha.

Dynamics of dry matter accumulation in internodes indicates source and sink relations during grain-filling stage of japonica rice

• We investigated the dynamics of internode dry matter (DM) from 21 days before anthesis to maturity for japonica rice. • We found a sharp reduction of internode DM between 20 and 30 days after anthesis (DAA). • Non-structural carbohydrates in internodes were significantly remobilized between 20–30 DAA. • A marked increase in internode DM at maturity was detected. • Internode DM can be viewed as an integrative index for source-sink balance. Storage of non-structural carbohydrates (NSC) in internode parenchyma before anthesis functions as a major carbon source for rice grain filling. In this study, two-year field and pot experiments with three japonica cultivars and two nitrogen (N) fertilization modes were performed, and dynamics of dry matter (DM) in internodes were quantified from 21 day before anthesis (DBA) to 60 day after anthesis (DAA; maturity). Results showed that in comparison to leaves and sheaths, DM in internodes varied dramatically, with a clear pattern of increasing at 21 DBA, peaking at 10 DAA, then dramatically dropping until 20 or 30 DAA, and finally refilling at maturity. The sharp reduction of dry matter in the internodes corresponded with the fastest rate of grain filling, indicating the importance of internode reserves for yield formation. On the other hand, the high rate of refilling in internodes at late stage implies the excess production of leaf photosynthetic assimilates. Similarly, starch content in internodes showed a pattern of decreasing at 20–30 DAA. To clarify the indicative meaning of internode reserves, we calculated their remobilization rate at 20 DAA and refilling rate at 60 DAA. Genotypic variations existed for the three cultivars, with a range of 15.17 %–36.37 % for remobilization rate and 54.36 %–104.33 % for refilling rates in 2018. Overall, N topdressing significantly increased the translocation of internode reserves for all three cultivars. Furthermore, our calculation showed that only about 10 % of the grain yield was formed during the second month of rice grain filling, indicating this period is less important for grain yield. Our findings help to clarify the significance of internode DM dynamics for rice management and should be beneficial to enhance our knowledge of source and sink relations, the fundamental component of crop yield formation.

In situ dry matter and crude protein disappearance dynamics in stockpiled limpograss

AbstractStockpiling warm‐season perennial grasses for winter grazing is an important management practice for beef cattle production systems in tropical and subtropical regions. Limpograss [Hemarthria altissima (Poir.) Stapf et C.E. Hubb.] has greater digestibility at late maturity than other commonly used warm‐season perennial grasses; however, decreased crude protein (CP) concentration may limit livestock performance. The objective of this study was to evaluate the in situ dry matter (DM) and CP ruminal disappearance kinetics of stockpiled limpograss herbage. Forage for the in situ study derived from a 2‐yr field experiment in which treatments were the factorial combinations of three cultivars (‘Kenhy’, ‘Gibtuck’, or ‘Floralta’) and three stockpiling periods (8, 12, or 16 wk) distributed in three replicates of a randomized complete block design. Effective degradability of DM was greater for Kenhy and Gibtuck compared with Floralta (614 and 611 vs. 575 g kg−1), and it declined linearly as stockpiling period increased from 8 to 16 wk (623 vs. 586 g kg−1). Herbage CP concentration (48–32 g kg−1 DM) also declined linearly from 8 to 16 wk, but rumen‐unavailable CP increased during stockpiling (257–438 g kg−1 CP), causing effective CP degradability to decrease (637–489 g kg−1 CP). Limpograss is a good option for stockpiled forage, and both new releases outperformed Floralta; however, concentration and availability of CP must be considered when defining a supplementation strategy.

Vegetation dry matter dynamics along treeline ecotone in Western Himalaya, India

The study aimed to assess dry matter dynamics of forests along treeline ecotone concerning environmental variability, and four representative forests, birch, kharsu oak, Himalayan fir and mixed forest along treeline ecotone (3250–3400 m asl) were selected in Kedarnath Wildlife Sanctuary, Western Himalaya. Temperature, precipitation and humidity data were recorded for complete 3 years (2008–2010). Field inventory for assessment of forest structure and dry matter was carried out in a 200 m transect in each forest along treeline using quadrats of different sizes for tree, shrub and herb layers. The biomass and net primary productivity (NPP) of woody vegetation was estimated using region-specific allometric equations and of the herb layer, by harvesting. Litter quantity and decomposition rates were assessed using litter traps and litter bags, respectively. The dry matter budget of treeline ecotone was represented using a compartment model. The mean annual temperature at treeline was recorded 6.6 ± 0.68 °C with warmest month average temperature of 12.6 ± 1.2 °C. The average forest biomass at ecotone was 33.27 ± 16.97 Mg/0.1 ha, ranged between 8.87 Mg/0.1 ha in open and early successional birch forest to 44.98 Mg/0.1 ha in dense canopy mixed forest. NPP ranged from 1.49 to 2.11 Mg/0.1 ha year−1. The birch forest exhibited the highest efficiency in annual dry matter accumulation in the canopy layer among all forests. The leaf litter decomposition rates (% weight loss) was highest for kharsu oak (74%) after 3 years. The study revealed that Western Himalayan treeline exhibit warmer summer and higher amounts of dry matter storage, production and decomposition rates. These treeline forests showed a higher dry matter assimilation rate and so the potential for carbon sequestration under a warming climate.