A new model is presented that relates the numbers of bolters in sugar-beet crops to an intensity of vernalization calculated as the accumulated number of hours between sowing and the end of June that temperatures were between 0 and 13 degrees C, with each temperature within this range differentially weighted for its vernalizing effect. The model allows varieties to be characterized in terms of a threshold number of vernalizing hours needed to induce bolting (the vernalization requirement) and the increase in the proportion of bolted plants with each additional 10 vernalizing hours accumulated above this vernalizing threshold (the bolting sensitivity). When parameterized for variety, the model allows the level of bolting to be predicted for crops sown on specific dates in particular locations. Data from variety-assessment trials done at a wide range of locations throughout the main UK sugar-beet growing areas between 1973 and 2006, and from early sown bolting trials done at a few sites between 2000 and 2008, were used to define specific aspects of the model. These included the range and weightings of vernalizing temperatures, the period during which vernalization occurs, and the temperatures likely to cause plants to become devernalized. The vernalization-intensity bolting model was parameterized and validated using separate subsets of the UK variety-assessment trial data. It was shown to be more discriminating and robust than an existing 'cool-day' model, which relates bolting to the number of days from sowing in which the maximum air temperature was below 12 degrees C. Examples are given of the use of the new model to assess the bolting risk associated with early sowing in different regions of the UK, to interpret recent patterns of bolting (especially the large numbers of bolters seen in some commercial crops in 2008), and its potential use as an advisory tool.
Super-sweet maize (shrunken2, sh2) has a longer post-harvest life than standard sweetcorn (sugary1, su1), but is less well-adapted to cold conditions. The objective of the present work was to determine if the replacement of su1 by sh2 alters the combining abilities of sweetcorn inbreds for adaptation to early planting under cold conditions. Two diallel sets of su1 and sh2 near-isogenic inbred lines were evaluated in a cold chamber and by early field planting. For most of the traits related to adaptation, except silking date, there were significant mutant x genotype interactions and the estimates of general combining ability (GCA) of each version of the same inbred were different, probably due to epistasis. Therefore, to widen the genetic base of the super-sweet germplasm for adaptation, conversion of the earliest su1 inbreds to sh2, ignoring other characteristics such as emergence or early vigour in early planting or cold tests, is proposed.
Six pairs of isogenic lines of Sorghum (Sorghum bicolor L. Moench) were sown in field plots in Montecillo, State of Mexico (2240 in altitude), in 2005 and 2006. Crosses A (female) x B (male) were done in each pair, In A-lines, the length of pistil, stigma, style and ovary, as well as the ovary width, were measured. In B-lines, Pollen diameter, viability (cytoplasm density) and production were evaluated. Pollen germination and pollen tube growth in the pistils of the A-lines, were quantified in vivo with aniline blue and epifluorescence 18 h after pollination (HAP), while fertilized pistils were Counted at 96 HAP. Histological studies on both pollinated and non-pollinated pistils were performed in one male-sterile line. Seed yield, mean-seed weight, seeds per particle and seed set (SS; seeds/flower/particle) were determined at harvest. Pollen viability was the variable most related to Pollen germination and Pollen tube growth. Stigma receptivity was not associated with its morphology. Growth of the pollen tube in stigma, style and ovary was observed in the transmitting tissue 18 HAP, running parallel to the vascular tissue. Yield under chilling field temperatures (minimum average of 6 and 8 degrees C) prevailing during flower development and pollination ranged from 7 to 12 g/panicle. The differences in seed production and SS among A x B crosses did not depend on the amount and viability of Pollen.
The present study investigated the effects of maternal plasma iodine concentration on twin- and triplet-born lamb plasma thyroid hormone concentrations, rectal temperature and maximal heat production. On pregnancy day 68 (P68), 16 twin- and 14 triplet-bearing ewes were randomly chosen from ewes that were injected intramuscularly with 1.5 ml of iodized peanut oil and ewes that were not. Selected ewes were grazed on ad libitum pasture from P68 until parturition. After parturition, lamb blood samples were collected within 5 min of birth and at 3, 12 and 24-36 h after birth. Lamb rectal temperatures were measured within 5 min of birth and at 1,3 and 12 h after birth. Lamb body weight, crown rump length and thoracic-girth circumference were recorded at 3 h of age, and the capability of the lamb to produce heat at 24-36 h of age was measured using indirect open-circuit calorimetry. Maternal iodine supplementation successfully increased plasma iodine concentrations of twin- and triplet-bearing ewes throughout pregnancy, but had no effect on the rectal temperature, thyroid hormone concentration and maximal heat production of twin- or triplet-born lambs. Compared with twin-born lambs, triplet-born lambs had lower birth weights, rectal temperatures and plasma T4 and T3 concentrations within 5 min of birth. Overall, under the conditions of the present study, maternal iodine supplementation offered no benefit in improving lamb heat production.
Root system senescence and nitrogen (N) release from red clover (Trifolium pratense L.) plants, grown under semi-sterile conditions and a controlled environment, were studied for 28 days following temporary or prolonged abiotic stress. Plants stressed temporarily, to simulate grazing, recovered with no additional N lost in leachate. In contrast, plants subjected to prolonged stress that simulated overwintering conditions and inhibited shoot re-growth survived stress lasting 7 days, but plant viability was reduced to 50% by 14 days and 0% at 21 days. There were no significant differences in root protein, catalase activity, root death index or total N loss in leachate over 21 days, but by 28 days total N loss in leachate increased to 214% above control levels, with a 433% increase in total oxidized N. This increase in N loss between 21 and 28 days indicated the start of cellular breakdown of the root system, coinciding with the failure of plants to recover. Key enzyme activities and protein concentrations in nodules decreased rapidly over 10 days' prolonged stress. cDNA-amplified fragment length polymorphism (AFLP) analysis identified contaminating bacterial and fungal genes, along with plant gene sequences with consistent or altered expression profiles. Four plant sequences, glyceraldehyde-3-phosphate dehydrogenase (Tp-gapdh1), nodule senescence reduced (Tp-nsr1), nodule senescence enhanced (Tp-nse1) and a cysteine protease gene (Tp-cp8) were differentially expressed throughout the plant: Tp-nsr1 and Tp-nse1 have potential as molecular markers for nodule senescence. Root and nodule death in agricultural legumes, such as red clover, are implicated in N release into watercourses and the wider environment. Differences in the ability of these plants to survive prolonged stress lasting 14 days, and the delayed release of root N into leachate until 28 days after the stress, highlight the potential for the development of new red clover varieties with different rates of root system senescence.
Field and pot experiments were conducted to investigate the effects of defoliation oil crop performance and the possibility of using defoliation as a method for conserving soil moisture. The Study was conducted during 2006-2008, over two growing seasons of winter wheat (Triticum aestivum L.) in the North China Plain. Three levels of defoliation (mild, moderate and severe) were imposed oil winter wheat in the field during the following crop phases and conditions: at heading, at anthesis Under water deficit conditions and at anthesis under two or three levels of irrigation. Additional pot experiments with three levels of defoliation under two water regimes were arranged. The results showed that both the intensity of defoliation and the timing of defoliation significantly reduced grain production. Under wet conditions the reduction was over 20 %, While under dry conditions the reduction was c. 12 %. Yield reduction was greater for defoliation at heading than at anthesis and it was mainly caused by a reduction in kernel weight. Mild defoliation (top three leaves retained) did not affect grain yield. Moderate defoliation (top two leaves retained) slightly reduced grain production. Root length density in the topsoil profile was significantly reduced by severe defoliation at anthesis under wet conditions, but it increased under dry conditions. Dry matter remobilization to grains under moderate and mild defoliation was increased and resulted in a relatively higher harvest index (HI). The photosynthetic rate of the leaves remaining after defoliation was enhanced under all soil Moisture conditions. Although defoliation reduced the seasonal water use (ET), the yield reduction was much greater than the reduction in ET under severe defoliation, resulting in lower water use efficiency (WUE). The results show that conserving soil moisture by removing leaves might not be an economic choice. Under the conditions of the present study, the WUE of winter wheat was not improved by defoliation; however, in very dry conditions the reduction in ET by defoliation might help the crop survive.
The genetic effects, including genetic main effects and genotype x environment (G x E) interaction effects, for oleic acid content (OAC) and linoleic acid content (LAC) at five different developmental times/stages were studied using unconditional and conditional genetic models for seed quantitative traits in diploid plants. The unconditional analysis results revealed that both OAC and LAC were simultaneously controlled by diploid embryo nuclear genes, cytoplasmic genes and diploid maternal plant nuclear genes and their G x E interaction effects. Effects on the embryo and cytoplasm were found to be more important for OAC at different developmental times while maternal effects, in combination with cytoplasmic effects, were more important for LAC at most development times. The conditional analysis revealed that the net effect from expression of maternal genes was more important for both traits at most developmental stages. The total narrow-sense heritability was high for both OAC and LAC, with general heritabilities being more visible for OAC and G x E interaction heritability being more important for LAC at most development times. The predicted genetic effects indicated that while most parents (with the exception of Youcai 601, Zhongyou 821 and Eyouchangjia) could be used for improving OAC of offspring, Double 20-4 was the most appropriate for improving LAC due to its better stability and positive values across environments at most development times.
Models that accurately describe and predict growth and nutrient utilization of fish call be useful in developing strategies to improve the economic and environmental sustainability of aquaculture operations. Current bioenergetics models are not sufficiently flexible to be applied to the wide range of conditions encountered in aquaculture. There is a need to move from bioenergetics approaches to more mechanistic approaches based oil nutrient utilization by fish. A non-ruminant nutrient-based growth model hits been Successfully used in pig production. The model explicitly describes the utilization of energy-yielding nutrients and metabolites for body protein deposition (Pd) and body lipid deposition (Ld) at the whole animal level. Partitioning of intake of energy-yielding nutrients between Pd and Ld is governed by a minimum ratio (minLP) of the body lipid mass (L) to protein mass (P), a maximum daily rate of Pd (PdMax), or maximum efficiency of using intake of the first limiting dietary essential amino acid (AA) for body Pd. The growth model was adapted to rainbow trout (Oncorhynchus mykiss (Walbaum 1792)) through parameterization and various modifications consistent with its framework. The fish nutrient-based model was evaluated by comparing model simulations With data from Various experiments carried out with rainbow trout. Significant discrepancies between model predictions and experimental observations were observed. The model predicted energy retention well but did not always accurately predict growth rate, nor Pd and Ld. Overall, the model underestimated growth rate (expressed as thermal-unit growth coefficient (TGC)) by 37% and Pd by 15 OX, and overestimated Ld by 13%. These discrepancies are probably attributable to differences in nutrient utilization and partitioning mechanisms between fish and pigs. The development of more reliable models requires better understanding of the nutritional and endogenous determinants of fish growth.
Genetic variability in carrots is a consequence of allogamy, which leads to a high level of inbreeding depression, affecting the development of new varieties. TO understand the extent of genetic variability in 40 elite indigenous breeding lines of subtropical carrots, 48 DNA markers consisting of 16 inter simple sequence repeats (ISSRs), 10 universal rice primers (URPs), 16 random amplification of polymorphic DNA (RAPD) and six simple sequence repeat (SSR) markers were used. These 48 markers amplified a total of 591 bands, of which 569 were polymorphic (0-96). Amplicon size ranged from 200 to 3500 base pairs (bp) in ISSR, RAPD and URPs markers and from 100 to 300 bp in SSR markers. The ISSR marker system was found to be most efficient with (GT)(n) motifs as the most abundant SSR loci in the carrot genome. The unweighted pair group method with arithmetic mean (UPGMA) analysis of the combined data set of all the DNA markers obtained by four marker systems classified 40 genotypes in two groups with 0-45 genetic similarity with high Mantel matrix correlation (r = 0.92). The principal component analysis (PCA) of marker data also explained 0-55 of the variation by first three components. Molecular diversity was very high and non-structured in these open-pollinated genotypes. The Study demonstrated for the first time that URPs call be used successfully in genetic diversity analysis of tropical carrots. In addition, in entirely a new set of microsatellite markers, derived from the expressed sequence tags (ESTs) sequences of carrots, has been developed and utilized successfully.
Agricultural crop management decisions often require data on hydraulic properties of soils. Little information is available on hydraulic properties of clay soils that are impounded by rainwater (known as 'Haveli' lands) every year during the monsoon season in large tracts of Madhya Pradesh in India. Estimating hydraulic properties using global pedotransfer functions (PTFs) is one possible way to Coiled such information. Rules in the widely used global PTF Rosetta were executed to obtain estimates of two important hydraulic properties, namely soil water retention characteristics (SWRC) and saturated hydraulic conductivity (K-s) SWRC estimates obtained with maximum input (particle size distribution, bulk density, field capacity and permanent wilting point) in Rosetta were relatively closer to the laboratory-measured data as compared with the estimates obtained with lower levels of input. Root mean square error (RMSE) of estimates ranged from 0.01 to 0.05 m(3)/m(3). Hierarchical PTFs to predict K, from basic soil properties were derived using statistical regression and artificial neural networks. Evaluation of these indicated that neural PTFs were acceptable and hence Could be used without loss of accuracy.
The objective of the current study was to develop, validate and describe a decision support system (DSS) to evaluate cull dairy cow finishing strategies. The DSS was developed within a Microsoft Excel framework. The purpose of a DSS is to assist the process of making accurate and repeatable calculations, assisting the decision on which cull cow finishing strategy is most profitable under individual farm circumstances. The model was based on data from two evaluation experiments including eight finishing strategies in total: ad libitum grass silage (GS); GS + 3 kg concentrate (GS + 3); 05 + 6 kg concentrate (GS + 6); GS + 9 kg concentrate (GS + 9); ad libitum grass silage prior to ad libitum spring grass (GS + G); 0.75 grass silage and 0.25 straw prior to ad libitum spring grass (GS + S) and finally grass silage plus 6 kg concentrate dry matter (DM)/cow/day and milked twice daily prior to ad libitum spring grass (EXTLAC). Stochastic budgeting was included in the model to account for variability in key input and output variables on the overall profitability of various finishing strategies. The stochastic input and output variables included in the model were initial carcass value, feed strategy, concentrate cost and final carcass value. Net profit per cow was selected as the output distribution. The mean net profit per cow with the GS, GS + 3, GS + 6, GS + 9, GS + G, GS + S and EXTLAC was (sic)85.3, (sic)73.7, (sic)95.6, (sic)58.5, (sic)158.8 and (sic)186.8 and (sic)283.0, respectively. Profitability for the EXTLAC strategy was stochastically dominant to all other strategies evaluated meaning a higher level of profit and a lower level of risk is associated with the EXTLAC strategy. The optimal strategy of cull cow beef production depends greatly on the prevailing economic environment, purchase and sale price, milk price, feed costs, housing and labour.
Winter barley was sown by conventional-tillage (CT) and minimum-tillage (MT) cultivation over three seasons. Each cultivation treatment was split so that straw was incorporated into the soil during cultivation in one split, while the other did not receive straw. Aphid occurrences in autumn and incidence of barley yellow dwarf virus (BYDV) in spring were compared. Similar investigations on winter wheat were made over a further three seasons. The method of cultivation affected the number of aphids on barley and wheat plants in autumn and on wheat heads in summer; MT had fewest aphids. Soil incorporation of straw during cultivation had a similar effect. Method of cultivation affected the incidence of BYDV disease, with MT having least infection. Straw-treated cereal plots had fewer aphids and less BY DV than no-straw plots. Aphids and virus reached damaging levels only in the first barley crop. In this season, MT barley had significantly fewer aphids (48% fewer) and significantly less BYDV (71% less) than CT. Straw-treated plots within the CT system had rather similar aphid infestation and BYDV incidence as no-straw plots. Barley grown in the MT system with straw added had significantly fewer aphids (68%) than in the case when no straw was added. Overall, aphids in autumn were significantly fewer on MT relative to CT cereals in three of the six seasons and significantly fewer on straw relative to no-straw plots in two seasons. Aphids on wheat heads in summer were significantly fewer in MT relative to CT plots in one of the three seasons. Aphids on heads were also significantly fewer on straw-treated plots within each system of cultivation in two seasons, while MT wheat with straw had significantly fewer aphids/head than those without straw in one season. BYDV was lower each season in MT barley and wheat when compared with CT crops. These differences were significant for two of the three seasons in which each crop was grown. There was a lower incidence of virus in straw-treated plots than in no-straw plots. This effect was significant for one of the three seasons in which barley and wheat were grown. Plant and tiller density did not differ significantly between MT and CT barley either with or without straw incorporation. Plant density of wheat in autumn was significantly lower for straw-treated plots relative to no-straw plots in one season. Wheat head density was lower for MT relative to CT in one season, while MT with straw had significantly fewer heads than CT plots with straw in two seasons. BYDV significantly reduced grain yield only in 2001/02 when incidence of the disease was high. Grain yield in 2001/02 was 0.95 t/ha (16%) greater for MT barley, due to less BYDV, than for CT. Straw-treated CT barley outyielded no-straw plots by 0.45 t/ha, while the comparable value for the MT system was 0.3 t/ha. The combined effect of MT plus straw had a 1.24 t/ha (21%) yield advantage over CT without straw. It is concluded that MT cereals sown at the same time as CT crops in autumn have a lower risk of aphid infestation and BYDV infection than CT crops. The soil incorporation of straw further enhances the beneficial impact of MT in reducing aphids and virus.
The objective of the current study was to apply the Vitti-Dias model to investigate phosphorus (P) metabolism in growing pigs fed a diet supplemented with microbial phytase. The basal diet contained maize, defatted rice bran, vegetable oil, soybean meal, limestone, salt and a vitamin and mineral mix. There was no inorganic P in the diet and phytase was added at levels of 253, 759, 1265 and 1748 phytase units (PU)/kg of feed. The compartmental model included four pools of P: (I) gut lumen, (2) plasma, (3) bone and (4) soft tissue. A single dose of P-32 was administered, and specific radioactivity was measured in plasma, faeces, bone and soft tissue (muscle, heart, liver and kidney) at different times post-dosing for calculation of P flows between pools. Total P absorbed showed a negative relationship with total P excreted in faeces and Was strongly correlated with bone P retention, suggesting that absorbed P was channelled to bone to address its physiological growth. Average efficiency of metabolic utilization of absorbed P was estimated to be 0.94, with 0.52 g/g of total net P balance being accreted in bone and the rest in soft tissue (including muscle and some vital organs). The Vitti-Dias model provided suitable representation of P interchange between compartments (in particular, flows between gut and plasma and partitioning of available P between bone and soft tissue), resulting in estimates of P flows comparable with values calculated from balance data.
In vitro gas production (GP) of substrate incubated with cow rumen liquor is commonly used to evaluate feed nutritional quality; GP is correlated with organic matter digestibility and metabolizable energy content. The hypothesis tested was that GP differs among liquors of ruminant species and is dependent on the natural dietary intake of the donors. Measurements were of 24 h GP of seven browse species using rumen liquor from a large (cow) and small (sheep) grazer and from a small intermediate feeder (goat). Mean GP for browse with goat liquor (7 +/- 2.4 ml per 200 mg substrate) was significantly (13 =0.019) higher than that with cow liquor (5 +/- 1.9 ml), and GP with sheep liquor (6 +/- 1.1 ml) was intermediate, not significantly different from the cow liquor (P=0.197) and the goat liquor (P = 0.061). There was a significant correlation in the ranking of the browses between goat and sheep (P=0.013) liquor using a Mantel test with 9999 permutations, which indicated a similar ranking of browses when using rumen liquor of either of these small ruminants. There were trends between both cow and sheep (P=0.096) and cow and goat (P=0.092) liquors. It was concluded that the dietary habits of ruminant species donors may affect in vitro nutritional studies when using rumen liquor.
The efficiency of nitrogen fertilizer use is as low as 0.30-0.35 ill most agricultural practices due to losses to the natural environment in many ways. Ammonia (NH3) volatilization is important in paddy rice fields. The present Study investigated the effect of a surface film-forming material (SFFM) oil NH3 volatilization from a paddy rice field, by model estimation using parameters from evaporative pan experiments. The modified Jayaweera-Mikkelsen (J-M) ammonia volatilization model was employed to simulate and elucidate the effect of SFFM in reducing ammonia volatilization from paddy fields. A parameter of k(f). value in the J-M modified model was introduced to represent the resistance of NH3 volatilization loss from SFFM. The simulated data fitted well with the prediction of the J-M modified model and field observations. The modified J-M model is Suitable for screening and verifying the new SFFM, and merits further study.
The current work was designed to compare 13 agronomic and four physiological traits in mungbean isogenic lines (ILs) with different leaflet sizes and numbers. The IL population was developed from a cross made in 2006 at Kasetsart University, Thailand, between two pure lines (one with five small and the other with seven large leaflets), followed by continuous selling of the progenies until F-6. The resulting four IL families each exhibited seven leaflet types, viz, three normal-sized leaflets per leaf, seven large leaflets, nine large, five small, seven small, nine small or 11 small. A trial was conducted in 2008 to compare the 28 ILs using a randomized complete block design with three replications. The large multiple-leaflet lines gave higher values for seeds/pod, pod size, seed weight, seed yield, leaf area, leaf area index and proportion of light interception, but fewer clusters of pods, branches and pods per plant than the small multiple-leaflet ILs. Seed yield/plant was positively correlated with pods/plant, seeds/pod, mean seed weight, light interception, leaf area and plant height at maturity. Leaflet size showed association with more traits than did leaflet number.
In order to assess the diet of lactating ewes fed at pasture and the relationship of diet quality to pasture characteristics and milk production (MP), 12 lactating ewes were monitored during five lactation cycles (LCs). Individual faecal samples were collected three times per LC and scanned using a Foss NIRSystem 6500 monochromator. The organic matter digestibility (OMD), organic matter intake (OM!), digestible OMI (DOMI) and the chemical composition of the herbage ingested, i.e. the crude protein (CP) content of the herbage ingested (CPi) and the acid detergent fibre and lignin contents of the herbage ingested (ADFi and ADLi), were determined. The MP of the ewes and the pasture characteristics were measured and their relationships with diet quality were analysed. OMI and DOMI were higher during the first and the fourth LC (P<0.01). OMD and CPi were higher during the second and the fifth LC (P<0.01). MP varied with OMI (P<0.01) and with DOMI (MP = 0.1362 x DOMI0.53, R-2=0.40, P<0.001), whereas it was negatively correlated with OMD (r = 0.46, P<0.001). OMD and CPi were both positively correlated with the CP content of the pasture (r = 0.25, P < 0.03; r = 0.50, P <0.001), whereas the ADFi was negatively correlated with CP content (r = 0.48, P<0.01). The variation in OMI, DOMI and MP, on the one hand, and OMD and CPi, on the other, throughout the different LCs illustrates the importance of measuring several parameters when evaluating diets at pasture.
Estimates of inbreeding effects in a landrace are necessary in order to acquire information on the presence of different types of gene action for important traits. Twelve lines with different levels of inbreeding coefficients (F = 0, 0.25, 0.50 or 0.75) were developed from three phenotypically selected families of a winter squash landrace (Cucurbita moschata Duchesne) between 2000 and 2002 in the area of Thermi-Thessaloniki, Greece. During 2003, a field experiment was established at this location to evaluate the lines. The agronomical characters measured were: the number and weight of total commercial fruits, days to first female blossom, seed weight, size of pollen grains and water-stress tolerance. Comparisons were also made of morphological characters, the dry matter, the total soluble solids and the pH of fruits. Lines with inbreeding coefficient F = 0.50 were found to have the highest values for most of the measured characteristics. Significant family x inbreeding interactions were found, revealing different trends for the linear, quadratic and cubic components of each family with inbreeding coefficients. Three F = 0.50 lines selected from within each representative family were evaluated along with four winter squash landraces from the C. moschata collection of the Greek Gene Bank, during 2004 in the area of Thermi. These F = 0.50 lines showed a superior performance of three components contributing to yield, indicating that one generation of selfing improved the agronomic performance maintaining concurrently the substantial characteristics of the landrace.