Dry Matter Absorption Research Articles

PROCWT: Coupling PROSPECT with continuous wavelet transform to improve the retrieval of foliar chemistry from leaf bidirectional reflectance spectra

The leaf optical properties model PROSPECT has been widely used to retrieve foliar chemistry in reverse mode from directional-hemispherical reflectance factor (DHRF) spectra measured with integrating sphere equipped spectrometers. With bidirectional reflectance factor (BRF) spectra, some researchers attempted to invert PROSPECT after a modification to the latest version of the model. However, the retrieval accuracy varies greatly with chemical constituents and can be low for some of them, such as dry matter content. This paper proposes a new approach called PROCWT by coupling PROSPECT with continuous wavelet transform (CWT) to suppress the surface reflectance effect and enhance the absorption features of chemical constituents. Instead of the reflectance spectra, the wavelet coefficient spectra generated after CWT were used to construct the merit function for model inversion. Given that the multi-scale decomposition of CWT enables enhancement of chemical-specific absorption features, the use of PROCWT at different scales of wavelet decomposition could lead to improved retrievals of biochemical parameters. The performance of PROCWT was evaluated for estimating foliar chemicals of wheat and rice crops from BRF spectra measured with a leaf clip equipped spectrometer over a two-year field experiment. PROCWT was also compared with the standard PROSPECT inversion (STANDARD), the PROSPECT inversion with the subtraction of surface reflectance (PROREF), and the simplified PROCOSINE (sPROCOSINE).Our results demonstrated that the contribution of surface reflectance component was significant for BRF spectra and the effect of surface reflectance could be suppressed by PROCWT as well as PROREF and sPROCOSINE. Compared with STANDARD, PROCWT and the two traditional methods significantly improved the retrieval accuracies for pigments and leaf water content, but only PROCWT produced significant improvement for dry matter content with a decrease of 14.79g/m2 in the root mean squared error (RMSE) (30% of the mean) over the entire experimental dataset by enhancing dry matter absorption features. High scales of wavelet decomposition were favorable for the estimation of carotenoid and water contents and low scales for the estimation of chlorophyll and dry matter contents. The difference in optimal scale revealed the separation of overlapping absorption features attributed to various chemical constituents. In addition, the newest PROSPECT-D outperformed PROSPECT-5B in the retrieval of chlorophyll content but not for carotenoid. This new physically-based approach could be beneficial to analysts attempting to retrieve leaf chemicals from BRF spectra alone and close-range reflectance imagery of crops and even other vegetation types.

Spectroscopic Estimation of Biomass in Canopy Components of Paddy Rice Using Dry Matter and Chlorophyll Indices

Crop biomass is a critical variable for characterizing crop growth development, understanding dry matter partitioning, and predicting grain yield. Previous studies on the spectroscopic estimation of crop biomass focused on the use of various spectral indices based on chlorophyll absorption features and found that they often became saturated at high biomass levels. Given that crop biomass is commonly expressed as the dry weight of canopy components per unit ground area, it may be better estimated using the spectral indices that directly characterize dry matter absorption. This study aims to evaluate a group of four dry matter indices (DMIs) by comparison with a group of four chlorophyll indices (CIs) for estimating the biomass of individual components (e.g., leaves, stems) and their combinations with the field data collected from a two-year rice cultivation experiment. The Red-edge Chlorophyll Index (CIRed-edge) of the CI group exhibited the best relationship with leaf biomass (R2 = 0.82) for the whole growing season and with total biomass (R2 = 0.81), but only for the growth stages before heading. However, the Normalized Difference Index for Leaf Mass per Area (NDLMA) of the DMI group showed the best relationships with both stem biomass (R2 = 0.81) and total biomass (R2 = 0.81) for the whole season. This research demonstrated the suitability of dry matter indices and provided physical explanations for the superior performance of dry matter indices over chlorophyll indices for the estimation of whole-season total biomass.

Canopy foliar nitrogen retrieved from airborne hyperspectral imagery by correcting for canopy structure effects

A statistical relationship between canopy mass-based foliar nitrogen concentration (%N) and canopy bidirectional reflectance factor (BRF) has been repeatedly demonstrated. However, the interaction between leaf properties and canopy structure confounds the estimation of foliar nitrogen. The canopy scattering coefficient (the ratio of BRF and the directional area scattering factor, DASF) has recently been suggested for estimating %N as it suppresses the canopy structural effects on BRF. However, estimation of %N using the scattering coefficient has not yet been investigated for longer spectral wavelengths (>855nm). We retrieved the canopy scattering coefficient for wavelengths between 400 and 2500nm from airborne hyperspectral imagery, and then applied a continuous wavelet analysis (CWA) to the scattering coefficient in order to estimate %N. Predictions of %N were also made using partial least squares regression (PLSR). We found that %N can be accurately retrieved using CWA (R2=0.65, RMSE=0.33) when four wavelet features are combined, with CWA yielding a more accurate estimation than PLSR (R2=0.47, RMSE=0.41). We also found that the wavelet features most sensitive to %N variation in the visible region relate to chlorophyll absorption, while wavelet features in the shortwave infrared regions relate to protein and dry matter absorption. Our results confirm that %N can be retrieved using the scattering coefficient after correcting for canopy structural effect. With the aid of high-fidelity airborne or upcoming space-borne hyperspectral imagery, large-scale foliar nitrogen maps can be generated to improve the modeling of ecosystem processes as well as ecosystem-climate feedbacks.

Brown and green LAI mapping through spectral indices

When crops senescence, leaves remain until they fall off or are harvested. Hence, leaf area index (LAI) stays high even when chlorophyll content degrades to zero. Current LAI approaches from remote sensing techniques are not optimized for estimating LAI of senescent vegetation. In this paper a two-step approach has been proposed to realize simultaneous LAI mapping over green and senescent croplands. The first step separates green from brown LAI by means of a newly proposed index, ‘Green Brown Vegetation Index (GBVI)’. This index exploits two shortwave infrared (SWIR) spectral bands centred at 2100 and 2000nm, which fall right in the dry matter absorption regions, thereby providing positive values for senescent vegetation and negative for green vegetation. The second step involves applying linear regression functions based on optimized vegetation indices to estimate green and brown LAI estimation respectively. While the green LAI index uses a band in the red and a band in the red-edge, the brown LAI index uses bands located in the same spectral region as GBVI, i.e. an absorption band located in the region of maximum absorption of cellulose and lignin at 2154nm, and a reference band at 1635nm where the absorption of both water and dry matter is low. The two-step approach was applied to a HyMap image acquired over an agroecosystem at the agricultural site Barrax, Spain.

The effect of temperature on feeding and growth characteristics of the sea urchin Lytechinus variegatus fed a formulated feed

We investigated the effect of culture temperature on feed intake, absorption, organismal growth, and tissue production of Lytechinus variegatus by culturing individuals at three different temperatures representing the normal range of temperature exposure in wild populations in the northern Gulf of Mexico. Large L. variegatus (ca. 42 + 0.6 mm diameter, 36 + 1.3 g wet weight, n = 97) were collected at St. Joseph Bay, Florida, in October 2001. Eight sea urchins were held individually in 1-L containers within an 80-L aquarium with recirculated synthetic seawater at 32-ppt salinity. Three aquaria with the containers were each placed in three incubators at temperatures of 16, 22, or 28 °C for 8 weeks. Sea urchins held at 22 °C had the highest rate of feed intake. Feed intake in individuals held at 16 °C decreased significantly during the first 2 weeks of exposure and then increased to values not significantly different from those held at 28 °C by week 6. The dry matter absorption efficiency of individuals held at 28 °C was significantly higher than those held at 16 °C or 22 °C. The percentage of organic matter in the feces did not vary significantly with temperature. Individuals increased significantly in diameter, wet weight, and gonad weight at all temperatures. The wet weights of individuals held at 22 °C were significantly higher than those held at 28 °C or 16 °C, which did not differ significantly. The gut weight varied inversely with temperature. The wet weight of gonads of individuals held at 22 °C was significantly higher than those held at 28 °C, but neither differed significantly from those held at 16 °C. Production efficiencies, both organismal and gonadal, were inversely proportional to temperature, indicating that the overall metabolic cost of production increased with increasing temperatures. Organism production efficiencies were lower and gonad production efficiencies were higher than those found in small sea urchins, emphasizing that patterns of nutrient allocation vary between small and large sea urchins. Physiological processes associated with feed intake, absorption, and nutrient allocations vary with temperature, but allow the sea urchins to maintain growth and gonad production at a variety of temperatures. These data suggest that temperatures near the upper limits do not promote efficient use of resources, an important consideration for future commercial culture. Since gonad (roe) production is the ultimate goal of many aquaculture operations, gonad production efficiencies will provide a valuable tool for evaluating the efficacy of various feeds and feeding conditions on gonad production.

Spectroscopic determination of leaf water content using continuous wavelet analysis

The gravimetric water content (GWC, %), a commonly used measure of leaf water content, describes the ratio of water to dry matter for each individual leaf. To date, the relationship between spectral reflectance and GWC in leaves is poorly understood due to the confounding effects of unpredictably varying water and dry matter ratios on spectral response. Few studies have attempted to estimate GWC from leaf reflectance spectra, particularly for a variety of species. This paper investigates the spectroscopic estimation of leaf GWC using continuous wavelet analysis applied to the reflectance spectra (350–2500 nm) of 265 leaf samples from 47 species observed in tropical forests of Panama. A continuous wavelet transform was performed on each of the reflectance spectra to generate a wavelet power scalogram compiled as a function of wavelength and scale. Linear relationships were built between wavelet power and GWC expressed as a function of dry mass (LWC D) and fresh mass (LWC F) in order to identify wavelet features (coefficients) that are most sensitive to changes in GWC. The derived wavelet features were then compared to three established spectral indices used to estimate GWC across a wide range of species. Eight wavelet features observed between 1300 and 2500 nm provided strong correlations with LWC D, though correlations between spectral indices and leaf GWC were poor. In particular, two features captured amplitude variations in the broad shape of the reflectance spectra and three features captured variations in the shape and depth of dry matter (e.g., protein, lignin, cellulose) absorptions centered near 1730 and 2100 nm. The eight wavelet features used to predict LWC D and LWC F were not significantly different; however, predictive models used to determine LWC D and LWC F differed. The most accurate estimates of LWC D and LWC F obtained from a single wavelet feature showed root mean square errors (RMSEs) of 28.34% ( R 2 = 0.62) and 4.86% ( R 2 = 0.69), respectively. Models using a combination of features resulted in a noticeable improvement predicting LWC D and LWC F with RMSEs of 26.04% ( R 2 = 0.71) and 4.34% ( R 2 = 0.75), respectively. These results provide new insights into the role of dry matter absorption features in the shortwave infrared (SWIR) spectral region for the accurate spectral estimation of LWC D and LWC F. This emerging spectral analytical approach can be applied to other complex datasets including a broad range of species, and may be adapted to estimate basic leaf biochemical elements such as nitrogen, chlorophyll, cellulose, and lignin.

Iron Bioavailability of Rats Fed Liver, Lentil, Spinach and their Mixtures

To study the effects of dietary iron source (basal diet-FeSO4 x 7H2O, liver, lentil, spinach, liver + lentil, liver+spinach and lentil+spinach) on iron bioavailability, fifty-six Albino Sprague Dawley derived male 21 days old rats were fed on iron-deficient diet (7.8 mg Fe kg(-1) diet) and the mentioned seven iron containing diets (40 mg Fe kg(-1) diet) for 10 days. Rats fed liver diet showed higher iron apparent absorption (52.1%), hemoglobin (Hb) gain (0.94 g/100 mL), Hb-iron gain (1.2 mg), Hb-regeneration efficiency (HRE%) (50.8%), relative efficiency of HRE% (106.5%), packed cell volume gain (2.22%) and mean corpuscular hemoglobin concentration (0.64 g dL(-1)). Liver resulted in an increase in these parameters when mixed with lentil and spinach diets. However, rats fed iron free diet showed the higher dry matter absorption.

The Effect of Temperature on Feed Consumption and Nutrient Absorption in Procambarus clarkii and Procambarus zonangulus

AbstractFeeding characteristics of acclimated red swamp crayfish Procambarus clarkii and white river crayfish Procambarus zonangulus were determined at 8, 14, 20, 26, and 32 C. Food consumption rates of crayfish were directly related to temperature. Feeding was minimal at 8 C. At 14 CP. zonangulus consumed significantly more feed (5.5% body weight (BW/d) than P. clarkii (1.8% BW/d). At 32 C P. clarkii consumed significantly more feed (23% BW/d) than P. zonangulus (10% BW /d), reflecting species‐specific thermal optimums for feeding. Differences in food consumption rates correspond to differences in the geographical distributions of these two species. Dry matter absorption rates ranged from 55% to 75% for both species without significant temperature effect. Patterns of protein and carbohydrate absorption were similar in P. clarkii and P. zonangulus. Protein absorption efficiency decreased from 45% to 10% as temperature increased from 8 C to 32 C. The total amount of protein absorbed increased seven‐ to ten‐fold as temperature increased. Soluble carbohydrate absorption efficiency was reduced at low temperatures. However, absorption efficiency increased approximately five‐fold as temperature increased from 14 C to 20 C, but did not change substantially as temperature was increased to 32 C. The total amount of carbohydrate absorbed increased approximately 15‐ to 26‐fold as temperature increased. The protein to carbohydrate utilization ratio was similar between species, but varied dramatically with temperature. Both species absorbed between 2.5 and four‐times more protein than carbohydrate at low temperatures (8 C and 14 C). At 32 C both species utilized approximately three times more carbohydrate than protein. In spite of reduced consumption at lower temperatures, crayfish absorbed a greater protein portion. At these low temperatures it appears that crayfish maximize the efficiency of protein absorption, presumably for maintenance and growth requirements. At high temperatures it appears that crayfish maximize energy intake, presumably to sustain higher metabolic rates due to increased activity levels. These apparent temperature‐dependent nutrient requirements may influence natural foraging strategies or, for species in aquaculture, the effectiveness of commercial feed preparations. At high temperatures P. clarkii was more effective in consuming nutrients than P. zonangulus and may be more successful than P. zonangulus at these temperatures.

The effects of dietary protein concentration on feeding and growth of small Lytechinus variegatus (Echinodermata: Echinoidea)

Understanding the nutritional requirements of Lytechinus variegatus is essential to define its role in the marine environment and necessary for successful culture of this species. Protein is an essential component for growth, yet the requirements for protein in most marine organisms are not known. Small Lytechinus variegatus (ca. 14 mm diameter, n=160) were collected at St. Joseph Bay, Florida in March 2000. They were held in aquaria and fed ad libitum one of four diets varying in protein concentration (9, 15, 21, or 33% dry weight) for 14 weeks. Diets ≥21% dry weight protein were sufficient for maximal growth and survivorship. Individuals fed a diet low in protein compensated by consuming higher quantities of food per gram wet weight. However, the protein was insufficient to support maximal growth and survivorship. Total dry matter absorption, protein absorption, and carbohydrate absorption of the prepared feeds were higher than reported for natural diets. Total production and production efficiency was lowest in those fed the low-protein diet. Gonad production occurred in individuals with test diameters smaller than reported previously in field populations and was lowest in those fed the low-protein diet. The acini of both females and males were predominantly composed of nutritive phagocytes, suggesting that growing L. variegatus use the gonad primarily as a nutrient storage organ and not for reproduction. In females the growth rate of oocytes increased with dietary protein. In males, protein concentration ≥21% resulted in an increase in the volume of germinal epithelium and a decrease in the volume of nutritive phagocytes. The minimal requirement for protein in L. variegatus from approximately 1 g to 15 g total weight is >15% dry weight for the conditions of this experiment. The requirement for a diet >15% protein corroborates with field studies that indicate L. variegatus consumes epibionts and animal tissues preferentially to seagrass, and that the microbial, microfloral, and microfaunal community living on the seagrass may provide the extra protein required for growth and survival of small L. variegatus.

Effect of soybean seeds treated with germination or fermentation on nutritional status and growth in developing rats with iron deficiency anemia

To investigate the interaction effect of iron-deficiency anemia and feeding soybean in different ratios and treatments to wheat flour, 84 albino male growing rats were used as biological model in this study. They aged 24-35 days and body weight 60-74 gr. They were divided randamlly into two main groups. First group contained healthy rats, which inturn divided into seven equal subgroups according to hemoglobin level and body mass. Second group contained induced anemic rats (iron depleted by bleeding about 15-20 drops of blood) divided into seven equal subgroups also. Both anemic and healthy groups were fed for 15 days experimental period the balanced experimental diets as follows: Wheat flour (WF, control diet), WF supplemented with 7.5% or 15% ground soybean seeds, WF supplemented with 7.5% or 15% germinated soybean seeds, WF supplemented with 7.5% or 15% fermented soybean seeds. Nutritional status, body weight gain, hemoglobin levels, growth rate, amount of diets consumed, feces eliminated weights, dietary and fecal iron contents, liver and spleen weights and their iron contents were estimated, dietary apparent iron absorption (AFeA%) and dry matter absorption (DMA%) were calculated. Analysis of variance and Duncan multiple tests of body weight gains, growth rates, amount of diets consumed, feces eliminated and their iron contents, liver and spleen weights, and their iron content values of anemic rats were lower than those of healthy rats. However, the AFeA% of anemic rats was higher than those values of healthy rats. Dry matter absorption was similar in both groups of rats. 15% germinated soybean seeds supplementation to WF indicated to have promising effects in preventing and treatment of iron-deficiency anemia.

Circadian variation of food intake and digestive tract contents in the rat

The variation of food intake and digestive tract contents over a period of 24 hours was measured in the free feeding rat kept under a 12:12 hr light:dark cycle (lights on at 0700 hr). After a cessation between 0700 and 1000 hr, the rate of food intake increased progressively during daytime followed by a marked increase and a plateau after lights went off. In the dark, dry matter in the stomach was almost ten times the levels of the light phase. In the major part of the high feeding period, the rates of food intake and gastric emptying equilibrated. Dry matter content of the intestine also followed circadian variations that were specific for each segment. The time-to-time content of the mid-gut segment was closely related to gastric emptying. The extent of dry matter absorption in the proximal intestine decreased continuously from the time lights went on and reached a minimum at 22 hr. Absorption in the distal segments was much less subjected to variation over 24 hours. In the free feeding situation, the changes induced by the light cycle on the rhythm of food intake were accompanied by marked modifications of digestive tract contents including those of the intestine. Data indicate a close relationship between gastric function and the middle portion of the intestine.

Process of Dry Matter Accumulation into the Kernel and Grain Characteristics of Japonica and Indica Rice

In order to confirm the process of dry matter accumulation into the Kernel, 20 panicles heading the even date were collected every day from 5 days after heading till maturity, and the spike-lets on the panicles were assorted according to the location on panicle into E, M, M' and L groups as in fig.4. The dry weight of each group collected every day was measured. The rsults obtained are summerized as follows: (1) In Tyukyo-Asahi, E. M, M' and L took 28, 30, 33 and 40 days to gain maximum dry-weight respectively, whereas 19, 20, 23 and 25 days were taken in Bluebonnet, as shown in fig.4. Indica varieties attained faster to mature stage and the disparity in days required to gain maximum dry-weight between E andL was less in comparison with japonica varieties. (table 1) Therefor, the divergence in moisture content among the kernels harvested in a field may be less in indicas and this character of indicas is considered to be more suitable for use of the combined-harvester and rapid drying of paddy. On the other hand, the competition for dry matter absorption among the kernels in a panicle will be harder in indicas for reason of short duration of dry matter absorption and large number of kernels per panicle. (2) In general, dry matter accumulation in rice kernels begins to concentrate 7-9 days after flowering at the central part of kernel and gradually spreads to the outer regions, and translucency follows the dry matter accumulation in the same order. (fig.1) At the time of the central part of kernel being translucent, indicas gained 33-35 per cent dry weight as compared to 25-28 per cent in japonicas. (fig.4, table 1) During translucency progressed from central part till 1/3 of lateral diameter on the transverse section of fully ripened kernel, indicas gathered 24-26 per cent weight, whereas japonicas gathered l5-19 per cent weight. During translucency spread from 1/3 of lateral diameter till 2/3 of lateral diameter, indicas got 21-24 per cent and japonicas got 25-29 per cent. After 2/3 stage, 20 per cent and 30 per cent was gained by indicas and japonicas respectively till fully ripened stage. The difference between indicas and japonicas in the process of dry matter accumulation is considered to be correlated with the difference of hardness (density of dry matter) distribution in the transverse section of kernel. (fig.7)

Absorption of Calcium and Phosphorus along the Gastrointestinal Tract of the Laying Fowl as Influenced by Dietary Calcium and Egg Shell Formation

The apparent absorption of calcium, phosphorus and total dry matter along the gastrointestinal tract of the laying hen, was followed using yttrium-91 as a non-absorbed tracer. Percentage calcium and phosphorus absorption appeared to be greater in the proximal parts of the intestine than in the distal parts. This difference was smaller for total dry matter. Percentage calcium absorption was not significantly influenced by its dietary level, nor did the latter influence the absorption of dry matter. Percentage absorption of phosphorus was, however, depressed by the higher dietary calcium level. Egg shell deposition was associated with increased calcium and to a smaller degree, phosphorus absorption. It did not influence dry matter absorption. A heavy endogenous phosphorus excretion was observed in the duodenum.