The Inheritance of Yield and Yield Components of Five Wheat Hybrid Populations Under Drought Conditions

The magnitude of genetic inheritance and expected genetic advance are important for the prediction of response to selection in diverse environments and provide the basis for planning and evaluating breeding programs. This work investigated the inheritance of traits related to drought in wheat under natural drought conditions. Cross combinations were made to produce F1 and F2 hybrid populations, which were evaluated in a randomized completed block design with three replications at University of Agriculture, Faisalabad, Pakistan. Six wheat varieties/lines and six derived F2 hybrids were studied to ascertain heritability and genetic advance for plant height, days taken to maturity, number of tillers per plant, spike length, number of grains per spike, 1000-grain weight, and grain yield per plant. Data were collected and subjected to statistical genetic analyses. Heritability estimates and expected genetic advance for plant height, days taken to maturity, number of tillers per plant, 1000-grain weight and grain yield per plant were high for the entire cross combinations while the estimates for spike length and number of grains per spike were relatively low. Our results suggest that improvement for these characters should be faster because of higher heritabilities and greater phenotypic variation. Prospects of genetic improvement for all the characters studied are evident. The most promising cross combinations were WL60 × LU26S and WL61 × LU26S. These traits, therefore, deserve better attention in future breeding programs for evolving better wheat for stress environments

The Yield Condition in the Mobilization of Yield-Stress Materials in Distensible Tubes

In this paper we investigate the yield condition in the mobilization of yield-stress materials in distensible tubes. We discuss the two possibilities for modeling the yield-stress materials prior to yield: solid-like materials and highly-viscous fluids and identify the logical consequences of these two approaches on the yield condition. As part of this investigation we derive an analytical expression for the pressure field inside a distensible tube with a Newtonian flow using a one-dimensional Navier-Stokes flow model in conjunction with a pressure-area constitutive relation based on elastic tube wall characteristics.Comment: 28 pages, 1 figur

Ab initio yield curve dynamics

We derive an equation of motion for interest-rate yield curves by applying a minimum Fisher information variational approach to the implied probability density. By construction, solutions to the equation of motion recover observed bond prices. More significantly, the form of the resulting equation explains the success of the Nelson Siegel approach to fitting static yield curves and the empirically observed modal structure of yield curves. A practical numerical implementation of this equation of motion is found by using the Karhunen-Loeve expansion and Galerkin's method to formulate a reduced-order model of yield curve dynamics.Comment: 11 LateX pages, 2 figure

Yield statistics of interpolated superoscillations

Yield Optimized Interpolated Superoscillations (YOIS) have been recently introduced as a means for possibly making the use of the phenomenon of superoscillation practical. In this paper we study how good is a superoscillation that is not optimal. Namely, by how much is the yield decreased when the signal departs from the optimal one. We consider two situations. One is the case where the signal strictly obeys the interpolation requirement and the other is when that requirement is relaxed. In the latter case the yield can be increased at the expense of deterioration of signal quality. An important conclusion is that optimizing superoscillations may be challenging in terms of the precision needed, however, storing and using them is not at all that sensitive. This is of great importance in any physical system where noise and error are inevitable.Comment: 22 pages, 18 figures. Accepted to J. Phys.

Yield gap and the shares of climate and crop management in yield and yield variability of staple crops in West Africa. [O-3330b-01]

" Yield gap " (Yg) is a key concept of agricultural science for identifying the room for improvement of yields through better management of the agroecosystem. in rainfed agriculture Yg is the difference between actual yield (Ya) and the theoretical water limited yield (Yw) that would be achieved if solar radiation, temperature and precipitations were the only factor limiting the crop's growth and yield. Changes in Yw over regions and years are due to climate-soil interactions that are not easily modified by crop management, whereas changes in Yg are due to limiting factors that are typically within the scope of crop management such as nutrient availability, weeds, and pests. We provide an example of yield gap estimates in semi-arid a frica, using yield and other agronomic data collected in famers' fields of Senegal in 1990 and 1991 and from 2006 to 2012. i t illustrates how contrarily to what most people would expect climate is not, on average, what most limits yields in that region: yet, actual yields are on average a quarter of water limited yield, and this is due to constraints whose reduction is technically possible albeit subject to the economic and environmental relevance of doing so. Most studies dealing with the impact of climate change on agriculture in West a frica compare Yw under present and future climate as predicted by climate models. t he magnitude of those predicted long term changes in Yw by 2050 is down to –20% in the worst scenario combining a +6°C change with a -20% rainfall change. s uch changes in water limited yields are certainly concerning, but they are remarkably small compared to the potential +390% increase that would result from closing the current yield gap. When considering yield variations observed across plots and years, and not anymore regional averages over a few years, what strikes is the stability of observed yields compared to variations of Yw. We used crop model simulations with historical series of 20 years of weather data to compare yield distributions over years of a crop grown using 3 contrasted levels of fertilisation and no incidence of weeds, pests or diseases. For each fertilisation level, the simulated yield reached a maximum value the 'best year' of the series. t he three fertilisation levels were chosen so that the maximum simulated yield reached 0.25 Yw, 0.5 Yw, and 0.75 Yw respectively. t he resulting simulated yield distributions show that even if management allows increasing the median yield, in many years the climate is the main limiting factor and fertilising has no or a slight impact only. i n other words, the way the current climate limits crop production in this region is by making uncertain the output of investing for high yields. Buying fertilizers or working hard for manure collection, transport and distribution do not translate, a certain number of years, into more production. For farmers struggling for the daily subsistence of their family, that kind of risk may not be justified while alternative use of family resources in cash and labour force provide less risky ways to produce subsistence means. Until recently, in many farming systems of West africa, the growth in food needs due to population growth in rural areas was matched thanks to increases in cultivated or pasted areas rather than increases in crop yields or livestock pressure on land (i.e extension rather than intensification of crop or livestock activities). When rural families reached the limits of this strategy, migrations of many kinds of distance and duration became the adjustment variable to the gap between resources available from farming and population needs. T his suggests that for many, it is less risky to leave home than to intensify cropping or livestock systems. Anyway, as job opportunities for migrants from the rural zones are currently low in West african cities and elsewhere, there are legitimate concerns about the way this strategy may soon reach its limit as well. i n terms of climate change, the worst scenario for farmers of that region would be if crop intensification became even more risky under future climate than at present. t here is thus an urgent need for joint agronomic and climate research to go beyond the prediction of Yw or of yield under unchanged crop management and determine whether or not the future climate will increase the yield risks associated with crop intensification in that region. But this should not divert from designing and implementing policies incentive to such intensification under present climate, as this might be much easier now than later. (Texte intégral

The yield and post-yield behavior of high-density polyethylene

An experimental and analytical evaluation was made of the yield and post-yield behavior of high-density polyethylene, a semi-crystalline thermoplastic. Polyethylene was selected for study because it is very inexpensive and readily available in the form of thin-walled tubes. Thin-walled tubular specimens were subjected to axial loads and internal pressures, such that the specimens were subjected to a known biaxial loading. A constant octahederal shear stress rate was imposed during all tests. The measured yield and post-yield behavior was compared with predictions based on both isotropic and anisotropic models. Of particular interest was whether inelastic behavior was sensitive to the hydrostatic stress level. The major achievements and conclusions reached are discussed

Effect of different sowing densities in mixed cultivation of blue lupin (Lupinus angustifolius) with spring crops on yield and quality

The aim of this investigation was to optimise the yield percentage of blue lupins in mixed cropping systems. Field experiments were conducted at two locations in Northern Germany (Institute of Organic Farming near Hamburg and Institute of Plant and Soil Science at Braunschweig). Two types of blue lupins, the determinate and branched type were cultivated together with spring barley, spring wheat or fodder peas in different seeding ratios (SR): 50% : 50%, 62,5% : 37,5 % and 75% : 25% of the respective pure cropping seeding rate. We present data on total grain yield, yield of blue lupins, yield percentage of blue lupins, protein content, and protein yield. Total grain yield decreased with increasing SR of blue lupins whereas, in contrast, the yield of blue lupins, protein content and protein yield increased. This shows the low competitive ability of blue lupins against the mixed cropping partners, particularly cereals. Therefore, the yield percentage of blue lupins in mixed cropping with cereals did not reach more than 25%. From the view of plant production and the purpose of animal nutrition the percentage of grain legumes should be higher and comparable to those of other crop mixtures like peas with spring barley or beans with oat

Size effects in dislocation depinning models for plastic yield

Typically, the plastic yield stress of a sample is determined from a stress-strain curve by defining a yield strain and reading off the stress required to attain it. However, it is not a priori clear that yield strengths of microscale samples measured this way should display the correct finite size scaling. Here we study plastic yield as a depinning transition of a 1+1 dimensional interface, and consider how finite size effects depend on the choice of yield strain, as well as the presence of hardening and the strength of elastic coupling. Our results indicate that in sufficiently large systems, the choice of yield strain is unimportant, but in smaller systems one must take care to avoid spurious effects.Comment: 7 pages, 8 figure