Yield Related Components Research Articles

Yield components in relation to grain yield losses of barley fertilized with nitrogen

Application of nitrogen (N) fertilizer above the optimum rate suppresses grain yield of cereals in environments in which water supply is limited towards the end of the growing season. The aim of this study was to examine the effect of N fertilizer application on yield components of barley. The two-rowed barley locally named Kantara was grown for eight growing seasons in different long-term rotational experiments at two locations under rainfed conditions (200 to 450 mm) in Cyprus. Four rates of ammonium sulphate (0, 30, 60 and 90 kg N ha−l) were applied at sowing.Nitrogen application linearly increased the number of spikes per unit area and linearly decreased the weight per grain. The number of grains per spike and grain yield per unit area showed a quadratic response to nitrogen application, in which an initial increase was followed by a reduction at higher rates of N application. Stepwise regression analysis showed that the importance of variation in each yield component for explaining variation in grain yield varied with season, with the weight per grain being usually the least important, though always being statistically significant. Most of the variation in grain yield was explained by the number of grains per spike and by the number of tillers M−2. Strategies for managing N fertilizer application for specific environment and rotation systems for avoiding yield loss are suggested.

Path Analysis of Tomato Yield Components in Relation to Competition with Black and Eastern Black Nightshade

Path analysis is a statistical method for determining the magnitude and direction of multiple effects on a complex process. We used path analysis to assess 1) the impact of black nightshade(Solarium nigrum L.) or eastern black nightshade(Solarium ptycanthum Dun.) competition on the yield components of `Heinz 6004' processing tomato (Lycopersicon esculentum Mill.) and 2) the relationship between tomato yield components and total and marketable yield. Either black or eastern black nightshade was interplanted with tomatoes at population densities from 0 to 4.8/m2. Path analysis revealed that increasing weed population density led directly to fewer green and total fruit per plant, two components of marketable yield. However, the percentage of culls per plant and fruit weight were not affected by nightshade population density. Using correlation coefficients alone would have lead to the erroneous conclusion that the percentage of culls did not affect marketable yield; our path analysis demonstrated that decreasing the percentage of culls through breeding or cultural practices will strongly affect marketable yield. The total number of fruit was the most important yield component in determining total and marketable yields per plant. Breeding and management practices that maximize fruit set, increase maturity at harvest, and decrease the percentage of culls would be expected to increase marketable yield.

Sweet corn responses to basal and top-dressed rates and sources of nitrogenous fertilizers

Sweet corn (Zea mays L. var. rugosa cv. Jubilee) was grown on a fine loamy clay krasnozem soil with banded nitrogen fertilizer at rates up to 200 kg N ha-1 from (NH4)2SO4 and 50 kg N ha-1 from each of NH4NO3 and urea. Some treatments were top-dressed with one or two applications of 50 kg N ha-1. The highest yield of both cobs (23.1 t ha-1) and fresh shoots (93.8 t ha-1) and the highest concentration of N in cobs and shoot dry matter was attained with 100 kg basal N ha-1 and two subsequent topdressings of 50 kg N ha-1 each, applied as (NH4)2SO4. From banded dressing alone, 150 kg N ha-1 produced the highest cob yield and the highest accumulation of N in cobs and shoot dry matter. Top-dressed N increased the yield of cobs and the yield and N concentration in shoots, but did not influence the N concentration in cobs. As N rates were increased, there was an increase in the weight of primary cobs, the weight and number of secondary cobs and more significantly, in the number of tertiary cobs. The source of N did not have any effect on the yield or most yield related components except yield and number of tertiary cobs, which were higher in the ammonium sulfate treatments. The contribution of nitrogen uptake efficiency NUPE and nitrogen ultilization efficiency NUTE to variations in nitrogen use efficiency NUSE was calculated and discussed.

Genetic effects of Vrn genes on heading date and agronomic traits in bread wheat

The Vrn1, Vrn2 and Vrn3 genes have different values of effects on heading date and related yield components. The genetic background and environment do not affect the ranking of Vrn genotypes according to earliness within near-isogenic line sets; however, they do influence the level of differences between heading dates of particular genotypes and between effect values, respectively. The frequencies of defined Vrn genotypes in the global set of spring bread wheat cultivars are associated with grain weight per plant predicted on the basis of Vrn gene effects averaged over backgrounds and over environments. Peculiarities of backgrounds and environments alter the grain yield ranges of Vrn genotypes. For early photoperiod-insensitive wheats, planted in stress conditions at grain filling, the highest yield was predicted for double dominant Vrn genotypes with Vrn3. This gene is rarely used by the breeders in middle latitudes and its wider adoption is encouraged.

Association Between Grain Filling Rate and Duration and Yield Components in Rice1

The identification of readily measured traits that are associated with higher yields of field crops is important to plant breeders. The objective of this research was to determine if differences in grain filling rate and duration existed in rice (Oryza sativa L.) and if so, were these grain filling parameters correlated with other yield related components of the rice plant.Fifteen genotypes of rice were selected to represent a sample having diverse agronomic characteristics. Samples of panicles of the 15 genotypes were taken at weekly intervals for approximately 6 weeks during the grain filling period. The cubic polynomial model was found to closely fit the dry weight data (r2 ≥ 0.95 for all genotypes). Grain filling rate and duration as well as other grain filling parameters were determined from the model. Correlation between the grain filling parameters with yield components indicated that grain firing rate was more important than duration in this study. Grain filling rate, in turn, was positively and highly significantly correlated with actual panicle weight and 100‐grain weight and negatively correlated with panicles m‐2.