Proportion Of Dry Matter Research Articles

Effects of Physically Effective Neutral Detergent Fiber Content on Intake, Digestibility, and Chewing Activity in Fattening Heifer Fed Total Mixed Ration

The objective of this study was to determine the effects of physically effective neutral detergent fiber (peNDF) content in total mixed ration (TMR) on dry matter intake, digestibility, and chewing activity in fattening Hanwoo (Bos taurus coreanae) heifers. The experiment was designed as a replicated 3×3 Latin square using 12 heifers. Fattening heifers were offered one of three diets [high (T1), medium (T2), and low (T3) peNDF] obtained by different mixing times (3, 10, and 25 min) for the same TMR feed. The peNDF content of TMR was determined by multiplying the proportion of dry matter retained by a 1.18 mm-screen in a Penn State Particle Separator by the dietary NDF content. The peNDF1.18 content was 30.36%, 29.20%, and 27.50% for the T1, T2, and T3 diets, respectively (p<0.05). Dry matter intake was not affected by peNDF content in TMR. Total weight gain in T1 group was significantly higher (p<0.05) than in T2 and T3 groups. However, weight gain did not differ between T2 and T3 groups. The feed conversion ratio decreased with an increase in the peNDF content (T1: 12.18, T2: 14.17, and T3: 14.01 g/g). An increase in the peNDF content of TMR was associated with a linear increase in the digestibility of dry matter, crude protein, crude fiber, neutral detergent fiber, and acid detergent fiber (p<0.05). Also, an increase in peNDF content of the TMR resulted in a linear increase in the number of chews in eating and ruminating (p<0.05), and consequently in the number of total chews (p<0.05). These results indicate that peNDF content affects digestibility and chewing activity. Consequently, the peNDF content of TMR should be considered for improving feed efficiency, digestibility, body weight gain, and performance in fattening heifers.

Digestion of wood-based hemicellulose extracts as screened by in vitro gas production method and verified in vivo using sheep

The objective of the present study was to evaluate the potential of pressurized hot water extracted hemicellulose fractions from various wood species as feeds for ruminants. In Experiment 1, the fermentability of several hemicellulose extracts was screened using an in vitro gas production method. The samples were extracted from spruce (Picea abies) including mainly galactoglucomannan (GGM), from birch (Betula pendula) consisting mainly of xylan and from larch (Larix sibirica) consisting mainly of arabinogalactan. The GGM and xylan samples were readily fermented by rumen microbes while arabinogalactan was not. Based on the in vitro study, GGM was chosen for an in vivo digestibility trial using sheep, where it was fed at increasing proportions of diet dry matter (0, 47, 94 and 141 g kg-1) in a Latin Square design. The in vivo organic matter digestibility of GGM was relatively low, 0.58, but PHWE extracted hemicellulose has some potential as a feed for ruminants.

Decomposition, contribution and soil organic matter balances of crop residues and vermicompost in maize-based cropping systems in southwest Mexico

Soil fertility depletion is one of the main concerns of the farmers in the Costa Chica, Mexico. The current crop management exacerbates nutrient cycling unbalances and threatens the sustainability of the common maize production systems. It is necessary to supply the soil with organic sources. Field experiments were established in farmers’ fields to estimate the decomposition rate and N release of organic materials: aboveground and belowground plant residues, and vermicompost. Decomposition was monitored using the litterbag method, and decomposition patterns were fitted by means of a dynamic mono-component mineralization model. To calculate the effects of crop residues retention and vermicompost on OM balance, five scenarios were evaluated with farm DESIGN model. The decomposition rate was greater during the first 4 months. After that period the remaining dry matter proportion of aboveground residues varied between 45 and 67%. In case of root residues, the dry weight loss ranged between 20 and 47% after the first month. For both types of residues, N released within the first month was 37%, on average. At the end of the sampling period 9 months, the remaining dry matter proportion of aboveground and belowground residues ranged from 30 to 55%, whereas more than 80% of their total N was released. After 6.5 months only 35% of the vermicompost mass was decomposed, but about 65% of its N was mineralized. Besides, around 70% of the vermicompost N was released during the first 30 days. In fields with vermicompost maize was responsible for 70% of total N uptake, on average. The N balance was 93% higher than maize fields without vermicompost. In scenario with 30% of crop residue retention along with vermicompost, OM balance was 86% higher than under current management. Vermicompost can be regarded as an attractive amendment for both crop N supply and soil organic matter build-up.

Dry matter partitioning and canopy traits in wheat and barley under varying N supply

Abstract The prediction of the allocation of carbon and nitrogen into the different organs, e.g., leaves, stems, roots of a growing plant is a pivotal part of mechanistic growth models. Based on 2 year (winter wheat) and 3 year (winter barley) field trials with different N treatments (0–240 kg N ha −1 ), the objectives of this study were to verify currently used parameters for (i) specific leaf area, and (ii) allometric relationships between leaf and stem dry matter (DM). Green area index (GAI) differed between years and increased with N supply rate. The course of the specific leaf area (SLA) within the growth period after winter showed a large variation between the years as well as between the N treatments. During stem elongation, SLA positively correlated with GAI in both crops, indicating that leaves became thinner when the canopy was denser. The allometric relationships between stem and leaf dry DM clearly varied with the growth stages. Stem DM of wheat showed a higher proportion of the total above-ground biomass compared to barley. The effect of N fertilization on allometry remained small during early growth stages in barley, whereas in wheat, an increased N supply significantly decreased the proportion of stem DM. Our results suggest similar GAI and SLA patterns for wheat and barley, albeit depending on the N supply. Especially, using a constant SLA in plant growth models seems to be not suitable.

Population dynamics and nitrogen allocation of Sonchus arvensis L. in relation to initial root size

To develop better mechanical management strategies, more information on the impact of root partitioning on changes in the population dynamics of Sonchus arvensis is needed. Therefore, the effects of root fragmentation of S. arvensis on shoot height frequency distributions, biomass production and nitrogen allocation were studied in an outdoor experiment in Sweden in 2008. Three artificial populations of S. arvensis of different initial root lengths but with the same total root length per area were planted. Shoot heights were measured at the onset of flowering and dry weight and nitrogen content of leaves, stems, buds and roots were quantified twice during the season. Height frequency distributions of the populations were bimodal, indicating the existence of two generations distinctly different in height growth pattern. Shorter root fragments produced shoots with a lower mean height compared to longer fragments. Plants originating from longer root fragments had higher dry weight and more nitrogen compared to plants from shorter root fragments. Dry matter production per square meter did not differ between the populations. The proportion of dry matter and nitrogen allocated to the different plant components (leaves, stems, buds and roots) at harvest did not differ between the populations. Over time, nitrogen was reallocated from leaves and stems to roots. Our results show that initial root length of S. arvensis per square meter, rather than the number of root fragments per square meter, is a good predictor of biomass at harvest, and that the degree of root fragmentation does not affect nitrogen allocation patterns. Root fragmentation, however, leads to a lower average canopy height for S. arvensis, and thus may be an effective weed control measure in combination with a crop which is competitive for light.

Effects of maize crop maturity at harvest and dietary inclusion rate of maize silage on feed intake and performance in lambs fed high-concentrate diets

This study investigated the effects of maize maturity at harvest and dietary inclusion rate of maize silage on feed intake, average daily gain (ADG) and carcass traits of growing ram lambs fed high-concentrate diets. Precision-chopped maize was harvested at two stages of maturity (Early: dough stage and Late: dent stage) and ensiled as round bales. Early or late cut maize silage was fed as the sole forage or together with grass silage, to 40 ram lambs in each of two consecutive years. The four treatments in each year were: (1) early cut maize silage as 50% of the forage dry matter (DM) proportion (E50), (2) early cut maize silage as 100% of the forage DM proportion (E100), (3) late cut maize silage as 50% of the forage DM proportion (L50) and (4) late cut maize silage as 100% of the forage DM proportion (L100). The proportion of forage in each of the diets was on average 42% on a dry matter (DM) basis and the concentrate consisted of dried distillers’ grains plus solubles, rolled barley and cold-pressed rapeseed cake in year 1 (Y1) or heat-treated rapeseed expeller in year 2 (Y2). Daily DM intake (DMI) was 1.24 and 1.40kg, averaged over treatments, in Y1 and Y2, respectively. Increasing the dietary inclusion rate of maize silage from 50 to 100% of the forage DM proportion resulted in increased DMI in Y1 (P<0.05) and increased carcass fatness in Y2 (P<0.01), whereas increased maturity stage at harvest tended to result in increased DMI in Y2 (P<0.10). Feed conversion ratio (FCR; kg DMI per kg ADG), was lower for the treatments E100 and L50 than for E50 and L100, respectively (P<0.01) in Y2. The body weight of the lambs increased linearly over time, in both years. In conclusion, maize silage can replace grass silage in the diets of high-producing lambs. Increased metabolizable protein (MP) to metabolizable energy (ME) ratio of the diet increased ADG of the lambs. Also, increased ADG decreased mega joule ME intake per kg ADG, in finishing lambs.

Physiological growth and gas exchange response of saffron (Crocus sativus L.) to irrigation water salinity, manure application and planting method

The objective of the present study is to investigate the effects of irrigation water salinity, cow manure levels and different planting methods on saffron growth rate and gas exchange. A split-split plot arrangement was conducted in randomized complete block design with irrigation water salinity levels (0.45 (fresh water, S1), 1.0 (S2), 2.0 (S3), and 3.0 (S4) dSm−1) as the main plot, cow manure levels (30 (F1) and 60 (F2) Mgha−1) as the subplot and planting method (basin (P1) and in-furrow (P2)) as the sub-subplot in three replications. Results showed that initial amount of planted corms were degraded by using saline water (EC higher than 2.0dSm−1) in the basin planting method and under F1 and F2 cow manure levels in consecutive growing seasons; however, we observed an acceptable increase in corm growth in high salinity levels (S3 and S4) under the in-furrow planting method. Assessment of the ratio of corm DW to the leaf DM showed that corms propagation were higher in the first year; however, in the second year higher weight proportions of dry matter were allocated to the leaves. Maximum saffron LAI and crop growth rate (CGR) decreased significantly as about 26% by using the highest water salinity level and these parameters increased as 37 and 61%, respectively by using the in-furrow planting method. Higher cow manure (F2) also increased LAI and CGR by 16 and 13%, respectively. Results of gas exchange parameters showed that photosynthesis rate (An) decreased as about 32% in the highest water salinity level. Higher manure application increased the An as about 18%. Also, An increased significantly by 29% under the in-furrow planting method compared with that in the basin. An was 17% higher in the second year than that in the first year and the conversion rate of photosynthetic production to shoot dry weight for developed saffron increased by about 47% due to leaf area index increase. High salt sensitivity of saffron could be remediated by using the in-furrow planting method and higher cow manure application rate.

Drought stress condition increases root to shoot ratio via alteration of carbohydrate partitioning and enzymatic activity in rice seedlings

To understand the underlying mechanism for plasticity in root to shoot ratio (R/S) in response to drought stress, two rice cultivars, Zhenshan97 (drought susceptible) and IRAT109 (drought resistant), were grown hydroponically, and R/S, carbohydrate concentration and partitioning, and activities of enzymes for sucrose conversion in seedlings exposed to drought stress condition (DS) imposed by polyethylene glycol 6000 were investigated. The R/S significantly increased under DS in comparison with that under well-watered condition. The proportion of dry matter and soluble sugar of roots markedly increased under DS. The R/S was negatively correlated with proportion of soluble sugar in stems, and positively with the proportions of soluble sugar and starch in roots. Drought stress condition significantly increased leaf sucrose-phosphate synthase (EC 2.4.1.14) activity and root acid and neutral/alkaline invertase (EC 3.2.1.26) activity. The R/S was positively correlated with leaf sucrose-phosphate synthase and root acid invertase activity, and negatively with leaf sucrose synthase activity in the cleavage direction. Our results indicate that the increase in R/S in response to DS is closely associated with the higher proportion of dry matter and soluble sugar in roots, and this occurs via an increase in leaf sucrose-phosphate synthase and root invertase activity, and thus more sucrose is available for transport from leaves to roots.

Effects of Dietary Sodium Bentonite and Mannan Oligosaccharide Supplementation on Performance, Egg Quality, Blood and Digestion Characteristics of Laying Hens Fed Aflatoxin Contaminated Diet

In this experiment, sodium bentonite (SB) (0.5% and 1%) and mannan oligosaccharide (MOS, 0.1%) were fed to laying hens each receiving approximately 120 ppb total aflatoxin (AF), and were compared to AF contaminated negative control (NC) and control without AF (C) groups. A total of 180 hens at 26 weeks of age from Barred Rock were tested for 12 weeks. No significant differences in liveability, feed intake, feed conversion ratio, egg quality characteristics except for egg yolk redness (a*) and blood parameters were observed among the groups. When compared NC with C, egg weight, egg mass and body weight gain were decreased. The addition of 0.5% SB (SB-1) increased egg production and egg mass compared to NC and MOS. The addition of 1% SB (SB-2) increased egg mass compared to NC. The AF contaminated diet (NC) caused a significant decrease in a* compared to C. Aflatoxin was not detected in eggs obtained from any of the treatments. Faeces pH was higher in NC than in C, SB-1 and SB-2 and similar to that of MOS. The proportion of dry matter of the faeces in C was higher than that of NC. As a result, SB appears to be more effective than MOS as a toxin-binding agent in counteracting the adverse effects of AF in laying hens.

Typology of dairy farming systems in the Mediterranean basin (Case of Algeria)

Characterization of breeding dairy cattle systems from the Mediterranean basin was conducted on 16 farms in the north center region of Algeria through a survey. Results are highly variable both structurally and in techno- economic management terms. The principal component analysis and clusters analysis have identified four groups of farms that differ in feeding strategies. The first group contains four farms that promote the use of forages (61.8% of the total dry matter (DM) intake). The costs are above the general averages (cost of production: 38.4 DA / liter ? 0.34 ? and cost of food in total production costs = 71.8%). The average annual productivity is about 4328.6 kg. Five farms of group 2 are characterized by milk yields below average (4146.5 kg). The concentrates represent only 39.3% of total DM intake. The cost of production (37.1 DA ? 0.33 ?/ liter of milk) and food costs are the lowest (65.17% of total production costs). The third group contains 5 farms dominated by profitable farms (4833.4 kg) and the lower cost of production (35.2 DA ? 0.31 ?). A relatively high proportion of DM is provided by forages (53.6%). Food accounts for 69.2% of the total production cost. The fourth group consists of two farms whose main characteristic is the total absence of forage production. This is associated with a significant contribution of concentrates in the global feed balance (48.8% of total DM intake). These concentrated foods were poorly converted into milk as recorded yields are the lowest (3561.2 kg). Production costs are highest (45.1 DA ? 0.40 ?) and relation price of food/total cost of production is very high (79.3%). So there are areas for improvement via land restructuring and the adoption of healthy feeding practices in order to ensure the profitability and sustainability of farms identified in this study.

Effects of physically effective neutral detergent fibre content on dry-matter intake, digestibility and chewing activity in beef cattle fed total mixed ration

Our aim in this study was to determine the effects of physically effective neutral detergent fibre (peNDF) in a total mixed ration (TMR) on feed intake, digestibility and chewing activity in beef cattle. The experiment had a replicated 3 × 3 Latin square desig, using three fattening Hanwoo (Bos taurus coreanae) steers with ruminal cannulas. Steers were offered one of three diets (high, medium or low peNDF content) obtained by mixing the same TMR for different periods of time (5, 13 and 25 min). peNDF content of TMR was calculated as [total chewing time/NDF intake (kg)] × dietary NDF content, and the proportion of sample dry matter (DM) collected in a ≥1.18-mm sieve is commonly used as the physical effectiveness factor in the equation. The peNDF1.18 contents of the high, medium and low diets were 25.97%, 21.10% and 17.94% (P &lt; 0.05). In addition, the proportion of particles collected on the 19-mm, 1.18-mm, and pan sieves changed linearly with an increase of TMR mixing time. Mean particle-size distributions of diets were 11.43, 24.11, 30.70 and 33.68 for 19 mm, 8 mm, 1.18 mm and pan, respectively. Eating rate and ruminating and chewing efficiencies were significantly decreased with reduced peNDF content, and DM intake was increased significantly (P &lt; 0.05). Lower peNDF content reduced the total number of chews significantly (P &lt; 0.05). Total time spent chewing associated with eating was not affected by peNDF contents. Digestibility of DM, crude protein and crude fat decreased with reducing peNDF content in the diet, but there was no significant difference among the three groups. These results indicated that peNDF affects intake, digestibility and chewing activity in beef cattle. Therefore, high levels of peNDF appears to improve TMR, as it can increase efficiency and may prevent ruminal disorders in Hanwoo steer.

Red clover increases micronutrient concentrations in forage mixtures

Forage crops provide micronutrients as well as energy, protein and fibre to ruminants. However, the micronutrient concentrations of forage plant species differ, legumes generally having higher concentrations than grasses. In addition to that there are also strong effects of soil type. Typically, the concentrations of one or several micronutrients in forage are too low to meet the nutritional requirement of dairy cows. We hypothesized that the overall micronutrient (Co, Cu, Fe, Mn, Mo, Zn) concentrations of forage mixtures are affected by the red clover dry matter (DM) proportion and site effects. This hypothesis was tested at three contrasting sites. The results showed that increased red clover proportion increased the overall concentrations of several micronutrients in the mixtures at all sites. At the site with the widest range of red clover proportion (0–70%) in the mixture, the Co, Cu and Fe concentrations more than doubled between the lowest and highest red clover DM proportion. At the other two sites a smaller increase in red clover proportion (from 10% to 25% or from 25% to 50%) also increased the overall concentrations of Co by up to 80% but less for other micronutrients. One of the sites generally had higher micronutrient concentrations in the crop and removed larger amounts of micronutrients with the harvested biomass compared to the other two sites. This could be explained by differences in pH and micronutrient concentrations of the soils at the sites. We conclude that increased red clover proportion in the sward has the potential to increase the overall micronutrient concentrations but that the effect of the soil is also a controlling factor.

Effects of Post-véraison Water Deficit on ‘Pinot noir’ Yield and Nutrient Status in Leaves, Clusters, and Musts

‘Pinot noir’ grapevines were grown in a pot-in-pot system using a red-hill-soil where volumetric soil water content (θv) was carefully controlled. Four-year-old vines were supplied with one of two irrigation regimes (wet or dry) between véraison and fruit maturity and the experiment was repeated over 2 years. From véraison to harvest, vines in the wet treatment received irrigation whenever θv approached ≈15% maintaining leaf water potential (Ψleaf) above –1.0 MPa. Vines in the dry treatment received irrigation when θv approached 11% to 12% and experienced significant water stress (Ψleaf ≈–1.4 MPa) before water was re-supplied. Vines were destructively harvested at véraison and at fruit maturity to determine biomass and nutrient content in the current season’s above-ground tissues. Fruit yield, maturity indices, and must nutrient composition were measured at maturity. Irrigation did not influence vine growth in either year nor did it influence yield or fruit maturity indices. Irrigation also had no influence on leaf, whole cluster, or must mineral nutrient concentrations. Vine growth, yield, and nutrient status in leaves and musts varied by year. Vegetative growth was greater in 2007 than 2008, whereas yield and cluster weights were greater in 2008. Also in 2008, whole clusters obtained a greater proportion of dry matter and nutrients after véraison when differing irrigation treatments were imposed. Nonetheless, irrigation did not affect must chemical composition. These findings suggest that periodic post-véraison water deficits that are moderate to severe have little effect on berry nutrient and sugar accumulation in ‘Pinot noir’ cropped at typical levels for this variety.

Feeding strategies and feed self-sufficiency of dairy farms in the lowland and mountain area of Western Switzerland.

The feeding strategy and the feed self-sufficiency of 34 commercial dairy farms in the western part of Switzerland were investigated throughout the year 2010. Feed ration composition of farms from the lowlands with relatively high proportions of maize were compared to farms from the mountain area with relatively high proportions of herbage in the rations. Dairy feeds were categorized into herbage, whole-plant maize and concentrate. The proportions of dry matter (DM), net energy for lactation (NEL) and metabolizable protein (MP) sourced from herbage, maize and concentrates were calculated. Dairy farms located in the mountain area had higher proportions of herbage DM in the ration than farms located in the lowland (70% vs. 51 %), as well as herbage-sourced NEL (66 % vs. 47%) and herbage-sourced MP (68% vs. 49%). In contrast, lowland farms showed a higher proportion of maize DM in the ration (31% vs. 17 %). The degree of self-sufficiency of the total feed ration of mountain farms was shown to be larger for DM, NEL and especially MP. A general negative relationship between the proportion of maize DM in the ration and the dairy herd MP self-sufficiency could be observed.

In Vitro Rumen Fermentation of Ration Supplemented with Protected Vegetable Oils

This experiment was designed to evaluate the effects of protected vegetable oils supplementation on in vitro fermentation characteristics, rumen microbial population, and methane production in cattle. The treatments were arranged in a complete randomized block design involving 2 factors i.e. oil type (sesame, canola, and flaxseed) and protection methods (non protected, calcium soap, and microencapsulation). Variables observed were rumen pH, N-NH3, total and molar proportion of VFA, dry matter and organic matter digestibility, population of protozoa and total bacteria, methane production, and hydrogen balance. Data were tested using Analysis of Variance (ANOVA) and the differences among treatments means were examined by Duncan Multiple Range Test. The oil type did not affect all variables measured. The protection method using microencapsulation significantly increased N-NH3 concentration. There was an interaction between oil type and protection method on total VFA concentration, molar proportion of VFA, and methane production. The supplementation of calcium soap-flaxseed oil significantly increased total VFA production, while the supplementation of microencapsulated flaxseed oil had the highest propionate concentration and H2 utilization, the lowest A:P ratio, and methane production. It is concluded that microencapsulated flaxseed oil was the best treatment to optimize rumen fermentation.

Milk fatty acid composition of dairy cows fed green whole-plant buckwheat, phacelia or chicory in their vegetative and reproductive stage

The hypothesis was tested that the phenological stage of dicotyledonous forages influences milk fatty acid (FA) composition of dairy cows. For this purpose buckwheat (Fagopyrum esculentum) and phacelia (Phacelia tanacetifolia; both in their first year of cultivation) as well as chicory (Cychorium intybus; second year) were cultivated in mixture with ryegrass (Lolium multiflorum). After 35 days of growth, feeding the green forages to 3×6 late lactating dairy cows at ad libitum access started. The realized dietary dry matter proportions of the test plants were (vegetative and reproductive stage): buckwheat, 0.60 and 0.55; chicory, 0.70 and 0.69; phacelia, 0.51 and 0.48. Experimental feeding lasted for 23, 17 and 26 days with buckwheat, chicory and phacelia, respectively. The complete diets additionally contained 2kg of concentrate and 1kg of barley straw per day per animal. Milk and feed samples were analyzed from every second day. Feedstuffs were analyzed for proximate contents, FA and fractions of phenolic compounds. In milk samples solids and FA were measured. Contents of FA and of phenol fractions decreased during advancing development stage in all test plants except total extractable phenols and total tannins in phacelia. This decrease was particularly pronounced for α-linolenic acid (ALA) and linoleic acid (LA) in buckwheat. Phenological stage had no influence on milk yield and gross composition, but ALA and LA proportions of milk fat declined with time in all groups. Proportions of ALA (14.2g/kg FA) and total poly-unsaturated FA in milk fat were highest with phacelia. Levels of conjugated linoleic acid (CLA) in milk fat were not affected by treatment or phenological stage. Vaccenic acid in milk fat was slightly elevated when feeding buckwheat and phacelia in the reproductive stage whereas it decreased with ongoing development in the chicory group. No systematic influence of phenological stage on the relative recovery of feed FA in milk fat occurred. The study did not confirm the hypothesis that the recovery rate of ALA would increase with maturing of the forages. In terms of generating a desired milk FA profile, phacelia and chicory seem however to be generally promising.

不同倍性冬小麦种内竞争能力的比较研究

In order to illustrate the competitiveness of three different ploidy wheats( the diploid Triticum monococcum,the tetraploid Triticum dicoccum,and the hexaploid Triticum aestivum Changwu 134),field experiment was conducted in Yangling with three planting densities( low,medium and high density,exactly 1,2. 5 and 4 million plants per hectare),two kinds of water conditions were taken as well respectively one with normal rainfall and irrigation while the other with none. The response of plant height,above-ground biomass,the tiller number per plant,grain yield and yield components to the density and water conditions among three wheat varieties was investigated. The result indicates that: 1) As wheat population density increased,the competition between individuals turned more intensive,biomass and tiller was obvious reduced,biomass accumulation rate declined. On the other side,the ample supply of moisture promoted the individual growth,difference between populations increased significantly along with individuals competition decreased. The diploid and tetraploid got the greatest height under medium density at harvest time,comparing with hexaploid what; 2) With the increase of population,the competition was strengthened and individual fecundity decreased gradually. Although spike density increased significantly,the strengthening of individual competition for resources limited the dry matter accumulation in post flowering,ultimately resulting in a significant declined in individual reproductivty,the final induced that the grain yeild did not increase with the population increased,especially under water deficit. The results showed that there is not a determined positive linear relationship between population size and yield. Under normal water supply both tetraploid and hexaploid got the highest yield under low density,which proved that high yield could be obtained under appropriate density in the premise of water saving with reasonable water strategy,improved population photosynthetic capacity,increased dry matter accumulation and proportion in post flowering; 3) Tiller number and plant height of Changwu 134 was lower thandiploid and tetraploid,the individual ability to compete for resources was lower,while the biomass accumulation rate had obvious superiority. Tetraploid showed the strongest ability in individual competition among the three ploidy wheats.Chagnwu 134 abtained the highest population yield under both drought and irrigation treatments,the two primitive species showed no significant difference meanwhile. Chagnwu 134 put up no obvious superiority on grain number per spike and spike density,but seed weight reached around 50 g /per 1000,and harvest index was close to 50%. Modern variety Chagnwu134 proved the the most significant yield reduction under drought condition,and showed up the strongest response to density under drought stress,which confirmed that drought influenced it most and it had a lowest drought resistance ability. The low competitive ability is the foundation in high population production. Modern wheat varieties put up more reasonable dry matter allocation ability,and they are more close to ideal plant type,which means that modern wheat variety receive high yield from the decrease of individual competiveness. All above-mentioned results provides the theory basis and good understand for water saving and high yield cultivation and the breeding in the arid and semi-arid area.

Effect of Root-zone Heating on Root Growth and Activity, Nutrient Uptake, and Fruit Yield of Tomato at Low Air Temperatures

Low-cost heating is needed to reduce chilling injuries, heating costs, and CO2 emission during greenhouse tomato production. To acquire information about the physiological and morphological effects of root-zone heating, an economical option at low air temperatures, we grew tomato plants on a nutrient film technique hydroponic system in a heated nutrient solution. We investigated the effects of short-term root-zone heating after transplanting and long-term heating until harvest. We measured short-term plant growth, nutrient uptake, root activity (xylem exudation and root respiration rates), root indole-3-acetic acid (IAA) concentration, internal root structure, and long-term fruit weight and dry matter distribution. The minimum root-zone temperature was maintained at 16.6°C, while the minimum air temperature (5.9°C) and the minimum root-zone temperature in the control (5.8°C) were lower than optimal. After 7 days of root-zone heating, root dry weight and relative growth rate increased compared with those of the control, accompanied by increased mineral nutrient uptake and xylem exudation. These changes may explain the increased shoot growth after 21 days of heating. In roots, development of the epidermis and stele, including the xylem, was promoted by heating, in contrast to previous research on root-zone cooling at high air temperature, which promoted xylem-specific development. Although the proportion of dry matter distributed to the fruit was not changed by root-zone heating, individual fruit size and total yield were higher than in the control due to a higher total dry weight in the heating treatment. Our results suggest that root-zone heating is an effective low-cost heating technology at low air temperature because of its effects on root activity, growth, and fruit yield, but that the mechanisms may differ from those in root-zone cooling at high air temperature.

Effects of water stress on dry matter accumulation and translocation in winter wheat cultivars planted at different ages

为了明确河南中部地区冬小麦品种改良过程中物质积累与转运特性及对水分亏缺响应的差异, 选取新中国成立以来6个不同年代主栽冬小麦品种, 采用测坑试验研究了冬小麦品种在不同水分胁迫(CK: 充分供水田间持水量的75%~85%; MD: 轻度干旱, 田间持水量的60%~70%; SD: 重度干旱, 田间持水量的45%~55%)下干物质生产与积累转运特性的演进特征及其与产量的关系。结果表明, 品种改良协调了干物质在各生育阶段的分配, 使花前和花后干物质积累与转运对籽粒的贡献更加平衡。在品种更替过程中, 株高和穗下节降低, 千粒重、籽粒产量和收获指数增加, 干物质积累总量无显著差异, 千粒重和收获指数的提高对产量增加起重要作用。在CK、MD和SD处理下, 20世纪90年代和2002年品种比20世纪50年代品种平均株高降低35.2%、36.2%和38.2%, 平均千粒重比增加31.7%、17.4%和56.3%, 平均籽粒产量增加40.4%、43.0%和52.4%; 20世纪90年代和2002年品种的收获指数比20世纪80年代及以前品种增加31.4%、22.3%和24.6%。CK处理早期品种干物质积累在抽穗至开花阶段超过现代品种。MD和SD处理的20世纪90年代及以后的品种花前干物质转运能力高, 茎秆干物质输出率增加, 花后贮藏物质积累降幅小, 干物质贮藏转运分配比例适宜, 对籽粒贡献率高, 是水分胁迫条件下现代品种高产的基础。

New Sainfoin Populations for Bloat‐free Alfalfa Pasture Mixtures in Western Canada

ABSTRACTSainfoin (Onobrychis viciifolia Scop.), a condensed‐tannin‐containing legume, when present in alfalfa (Medicago sativa L.) pasture prevents bloat in grazing cattle. However, old sainfoin cultivars do not persist in alfalfa stands for long and in new mixed stands do not regrow at the same rate as alfalfa after cutting or grazing. This multiyear and multilocation study was initiated to determine if new sainfoin germplasm developed for their ability to survive with alfalfa can perform better than old cultivars in western Canada. In this study new sainfoin populations in pure stands persisted same as ‘Nova’ for 4 yr. In hay trials at Lethbridge under rain‐fed and irrigated conditions, four (3432, 3519, 3900, and 3902) and three (3519, 3901, and 3902) new sainfoin populations produced significantly higher dry matter (DM) than Nova, respectively. In another set of tests where multiple harvests were taken at Lethbridge (irrigation) and Saskatoon (rain‐fed), the new sainfoin populations produced higher DM yields than Nova in pure stands, persisted for three production years in mixed stands while contributing &gt;20% DM for bloat prevention at each harvest. Nova proportions in mixed alfalfa stands decreased after the first production year. At Swift Current, however, new sainfoin populations produced significantly lower DM yield than Nova in pure stands and similar DM yield and proportions in mixed stands. Therefore, the new sainfoin populations tested may help improve hay or pasture production in most, but not in all, parts of western Canada.