Yield Related Components Research Articles

Response of Sunflower Cultivars to Deficit Irrigation

A 2-year study was conducted to determine the response of four sunflower cultivars (Master, Lakumka, Favorite and Berezanski) to different irrigation regimes: 45 (control), 60, 75 and 90% (I1–I4) of maximum allowable depletion (MAD) of available soil water (ASW). Severe deficit irrigation (I3 and I4) significantly decreased water-use efficiency, radiation use efficiency, yield and yield-related components. The results also showed that water deficit, compared to full-irrigated treatment (I1), increased the activity of all antioxidant enzymes in leaves. Master had the highest seed yield in full and limited irrigation as well as the highest antioxidant enzymes content. Sunflower plants extracted most of the soil moisture from 0 to 50 cm soil layer. Therefore, it is recommended that only the 0–50 cm soil profile be considered for scheduling irrigation. Measured and simulated results revealed a special irrigation regime threshold for each cultivar with respect to seed yield. The response rate to irrigation regime ceased in higher irrigation rates as I join (65, 63, 65 and 70% MAD for Master, Lakumka, Favorite and Berezanski, respectively). Moreover, all estimated I join for all cultivars were higher than the current recommendation of 50% MAD. This shows the ability to sustain the yield of these sunflower cultivars in the study region under deficit irrigation. The seed yield of all four cultivars tended to respond similarly to irrigation in both years, but Master was more efficient than the remaining three cultivars with respect to the response to diverse treatments.

Precise mapping of a quantitative trait locus interval for spike length and grain weight in bread wheat (Triticum aestivum L.)

The spike characteristics length, spikelet density and fertile floret number are related yield components and are important in cereal improvement. QSpl.nau-2D is a major quantitative trait locus controlling spike length (SPL) detected in the recombinant inbred line population developed by crossing wheat (Triticum aestivum) cultivars Nanda2419 with Wangshuibai. In this study, to validate its genetic effect and determine its precise location, QSpl.nau-2D’s near-isogenic line (NIL) was developed using Mianyang99-323 as the recurrent parent through marker-assisted selection. Field trials showed that the NIL not only had significantly longer spikes on average than the recurrent parent but also had significantly higher grain weight, but did not differ in spikelet number and kernel number per spike. In the F2 population derived from a cross of the NIL with Mianyang99-323, QSpl.nau-2D functioned like a single gene and conditioned the SPL in a partially dominant manner, and was thus designated as HL1 (for head length). To precisely map HL1, 89 recombinants, consisting of 11 genotypes, were identified in the NIL-derived F2 population of 674 plants by using markers in the Xwmc25–Xgpw4080 interval. Phenotyping these lines showed that the introduction of a 0.9-cM interval flanked by Xcfd53 and DG371 in Nanda2419 resulted in longer spikes and a higher grain weight in the NIL. The availability of markers closely linked to HL1 could facilitate its use in breeding programs.

Character Association and Parent Progeny Regression Studies for Yield and its Related Traits in Segregating Generations of TGMS Rice (Oryza sativa L.)

The aims of this study were to determine the response to selection for high grain yield and yield related components, to estimate the heritability of these traits, to compute the correlation of grain yield with yield components and to estimate the genetic potential transferred from one generation to other by using different segregating generations of rice (Oryza sativa L.). Various segregating populations (F2, F3 and F4) of the cross, TS 29 / CO(R) 49 were evaluated for yield and its related traits. The results indicated that correlation studies in F3 generation had positive association of single plant yield with fertility percentage, number of productive tillers per plant, panicle length, panicle exertion percentage, stigma exertion percentage and spikelet fertility percentage. Study on parent-progeny regression revealed positive significant regression and correlation coefficient estimates observed in F3-F4 generation for days to 50 per cent flowering, number of productive tillers per plant, panicle length, panicle exertion percentage and stigma exertion percentage which indicated that F3 are good indicators of F4 performance for all these traits. Narrow sense heritability increased with advancement of generation from F2 to F4 indicating the additivity of gene effects for number of productive tillers per plant, panicle length and panicle exertion percentage. It indicated the chances of selecting high yielding genotypes at early generations based on these characters are valuable.

Heterosis Studies in Chilli (<i>Capsicum annuum </i>L.)

The estimation of heterosis in 72 hybrids for yield and other 13 yield related component traits were studied following Line x tester design in chilli. Maximum heterosis (49.09 %) for dry fruit yield per plant and fruit weight (21.70 %) over standard check was observed in the cross Co-1 x Byadagi dabbi and for plant height and number of primary branches the cross GPC-82 x Singanahalli local. The hybrid Punjab Lal x KDC-1 had more number of fruits per plant, while Puri red x Lokur local and Puri red x KDC-1 were early for days to 50 per cent flowering. The hybrid G-3 x VN-2 exhibited highest heterosis for fruit diameter and pericarp weight. For fruit length and number of seeds per fruit the cross Co-1 x Byadagi dabbi while, S-32 x Lokur local showed maximum standard heterosis for dry fruit yield per plant. The hybrids Co-1 x Byadagi dabbi (40.09 %), Co-1 Lokur local (40.97 %), G-3 x Lokur local (39.92 %), Co-1 x KDC-1 (36.10 %), G-4 x Byadagi dabbi (34.19 %) and Kunkaur-3 x Byadagi dabbi (32.66 %) were considered most heterotic hybrids for yield and yield related components viz., number of secondary branches, number of fruit per plant, fruit length, fruit weight and pericarp weight.

Identifying loci influencing grain number by microsatellite screening in bread wheat (Triticum aestivum L.)

Grain number (GN) is one of three major yield-related components in wheat. We used the Chinese wheat mini core collection to undertake a genome-wide association analysis of grain number using 531 SSR markers randomly located on all 21 chromosomes. Grain numbers of all accessions were measured in four trials, i.e. two environments in four growing seasons. Association analysis based on a mixed linear model (MLM) revealed that 27 SSR loci were significantly associated with mean GN (MGN) estimated by the best linear unbiased predictor (BLUP) method. These included numerous breeder favorable alleles with strong positive effects at 23 loci. Significant or extremely significant differences were detected on MGN between varieties conveying favored allele and varieties with other alleles. Moreover, statistical simulation showed that the favored alleles have additive genetic effects. Although modern varieties combined larger numbers of favored alleles, the numbers of favored alleles were not significantly different from those in landraces, especially those alleles contributing mostly to the phenotypic variation. These results indicate that there is still considerable genetic potential for use of markers for genome selection of GN for high yield in wheat.

Quantitative Trait Locus Mapping of Yield-Related Components and Oligogenic Control of the Cap Color of the Button Mushroom, Agaricus bisporus

As in other crops, yield is an important trait to be selected for in edible mushrooms, but its inheritance is poorly understood. Therefore, we have investigated the complex genetic architecture of yield-related traits in Agaricus bisporus through the mapping of quantitative trait loci (QTL), using second-generation hybrid progeny derived from a cross between a wild strain and a commercial cultivar. Yield, average weight per mushroom, number of fruiting bodies per m(2), earliness, and cap color were evaluated in two independent experiments. A total of 23 QTL were detected for 7 yield-related traits. These QTL together explained between 21% (two-flushes yield) and 59% (earliness) of the phenotypic variation. Fifteen QTL (65%) were consistent between the two experiments. Four regions underlying significant QTL controlling yield, average weight, and number were detected on linkage groups II, III, IV, and X, suggesting a pleiotropic effect or tight linkage. Up to six QTL were identified for earliness. The PPC1 locus, together with two additional genomic regions, explained up to 90% of the phenotypic variation of the cap color. Alleles from the wild parent showed beneficial effects for some yield traits, suggesting that the wild germ plasm is a valuable source of variation for several agronomic traits. Our results constitute a key step toward marker-assisted selection and provide a solid foundation to go further into the biological mechanisms controlling productive traits in the button mushroom.

Foliar application of the exogenous plant hormones at pre-blooming stage improves flowering and fruiting in cashew (Anacardium occidentale L.)

The problem of declining tree yield has led to an investigation into the effectiveness of foliar application of exogenous hormones to improve flowering, fruit set, and fruit retention in cashew. Five exogenous hormones, one Gibberellic Acid (GA3) and four Auxins (IAA, IBA, NAA, and 2,4-D) at seven different rates of application (0 mg L−1, 10 mg L−1, 25 mg L−1, 50 mg L−1, 100 mg L−1, 250 mg L−1, and 500 mg L−1) were tested on six yield-related components of the two Brazilian cashew genotypes. This trial was a factorial split-split-plot design with each treatment replicated five times within a tree and three replications (three trees) per genotype. Responses varied significantly between exogenous hormones, concentrations and genotypes. The cashew plants used showed hormone-specific and optimum concentration response patterns. Of the five exogenous hormones tested, GA3 was most effective as its application at 50–100 mg L−1 gave five-fold improvements in flowering (precocity and number of hermaphrodite flowers) and fruiting, and about 69% increase in fruit retention ability and 25% in nut size. Panicles treated with GA3 also produced relatively bigger nuts compared to the untreated. Days to flowering was found to be hormone sensitive, while production of hermaphrodite flowers, fruit set, and nut development tended to be concentration specific. The GA3 exhibited a broad concentration tolerance among the five exogenous hormones investigated. Our data showed that using GA3 at 50 mg L−1 will enhance flowering precocity, shorten flowering duration, increase production of hermaphrodite flowers and fruit set significantly, and resultant nuts develop optimally with high percentage retention. Thus, it suggests cashew yield could be increased by exogenous foliar application of GA3 at 50–100 mg L−1 at pre-blooming stage.

Development and Evaluation of Primary Introgression Lines of Rice by Advanced Backcross QTL Strategy for Gaozhou Wild Rice (<i>O. rufipogon</i>)

Rice ( Oryza sativa L.) is the major cereal crop in China. The modern rice cultivars have narrow genetic base for most of the available traits, wild relatives of rice species contain trait-enhancing genes. The goal of this study was to identify introgression lines that can significantly increase yield in cultivated rice by yield-related traits from an inter-specific advanced backcross population (AB-population) between O.statia×O.rufipogon. AB-population ( O. statia ' Yuexiangzhan'× O. rufipogon ‘G52-9’) has evaluated using statistical methods for 17 agronomic traits pertaining to yield and yield-related components. Our studies indicated that AB-population had higher values for most traits analyzed in comparison to the recurrent parent, Yuexiangzhan. According to the statistical results, about 33.20% of the BC3F1 lines showed better than Yuexiangzhan in some traits. Grain shape and grain weight have selected for QTL mapping as an illustration of AB-QTL analysis. A total of 23 QTLs were identified for grain length (GL), grain width (GW), Grain length/grain width (LW), and grain weight (GWt). Phenotypic variation of each QTL ranged from 3.77%-28.67%. The grain weight of the recurrent ‘Yuexiangzhan’ was improved 15.10%, 28.67%, 26.29%, 24.28% and 12.90% by five main QTLs of GWt (from Gaozhou wild rice). This study confirms that wild progenitor species present potential donor sources for some complex traits and the advanced backcross population provides an efficient source of gene pool for future breeding programs. Therefore, Gaozhou wild rice is an efficient source of gene pool and can further utilize.

Determining Possible Relationships between Yield and Yield-Related Components in Forage Maize (Zea mays L.) Using Correlation and Path Analyses

This study was carried out to determine the optimum plant density and nitrogen rate in maize (Zea mays L.) under the ecological conditions of the Southern Marmara Region. For this purpose, maize was grown at different plant densities and was fertilized with different rates of nitrogen during 2006 and 2007. The dry forage yield, plant height, first ear height, stem diameter, leaf number plant-1, ear number plant-1, leaf ratio, stem ratio, ear ratio, ear diameter, leaf area index, and light interception were measured for all the treatments applied. The values of each parameter mentioned above were reorganized without regard to treatments or with regard to the highest and lowest values of plant density and nitrogen rates and were evaluated to determine the relationships between the dry forage yield and yield-related components. For this purpose, the direct and indirect effects of the corresponding components on dry forage yield were determined by using correlation and path analyses methods. The data averaged over two years, regardless of the treatment effects indicated that the relationship between the dry forage yield and each yield component except for stem ratio was positively significant. Path analysis revealed that most of the yield components had direct effects on the dry forage yield. According to this study, greater priority must be given to first ear height, leaf ratio and light interception to optimize silage maize yield. When the highest and the lowest plant densities and nitrogen rates were considered, it was understood that the nitrogen application had a greater effect on the dry forage yield than the plant density did.

Registration of Arkot 9811 and Arkot 9815 Germplasm Lines of Cotton

Arkot 9811 (Reg. No. GP‐919, PI 658215 and Arkot 9815 (Reg. No. GP‐920, PI 658216) are noncommercial breeding lines of cotton (Gossypium hirsutum L.) that were released by the Arkansas Agricultural Experiment Station in October 2009. Arkot 9811 was derived from a 1998 cross of ‘FiberMax 989’ and Arkot 9108. Arkot 9815 was derived from a 1998 cross of ‘GC‐251’ and Ark 8717–17–13, an advanced breeding line that was derived from crossing two F1 populations, one derived from crossing ‘DES 119’ and Miscot 7803–52 and the other one derived from crossing Miscot T8–27 and Miscot 8006. Lint yields of Arkot 9811 and Arkot 9815 were equal to two check cultivars in 15 Arkansas tests. Among the 32 entries evaluated in all 10 locations of a regional test in 2007, Arkot 9811 and Arkot 9815 produced the second and third highest lint yields, respectively. Basic yield and related yield components (number of seed per area, lint index, seed index, and fibers per seed) of Arkot 9811 were equal to those of ‘DP 393’. Arkot 9815 produced fewer seed per area, higher lint percentage, and fewer fibers per seed than DP 393. Height and maturity of both lines were similar to those of DP 393. Fiber properties of Arkot 9811 and Arkot 9815 were inferior to those of DP 393, producing higher micronaire and shorter length. Both lines produced moderate leaf pubescence ratings but were less glabrous than DP 393; however, the bract trichome density of both lines was less dense than that of DP 393. Both lines expressed resistance to bacterial blight. Arkot 9811 expressed resistance to tarnished plant bug equal to that of ‘SG 105’, while Arkot 9815 expressed higher resistance than either check cultivar. The relative yield, maturity, and line‐specific host‐plant resistance traits make these lines valuable to cotton breeding programs.

Nitrogen dose and plant density effects on popcorn grain yield

Popcorn (Zea mays everta Sturt.) is a popular and nutritious snack food. Environmental factors affecting grain yield and yield-related components of popcorn are needed to compensate increasing demand. This research was conducted to determine the effects of nitrogen fertilizer application rates and plant densities on grain yield and yield-related plant characteristics of popcorn in Hatay, located at Southern Mediterranean region of Turkey, during 2002 and 2003. The experiment was designed in a randomized complete block design with a split-plot arrangement with three replications. Nitrogen doses of 0, 120, 180 and 240 kg ha¹ were arranged in the main plots and plant densities of 60,000, 74,000, 88,000 and 102,000 plants ha¹ were arranged in the sub-plots. Popcorn grain yield and yield-related traits were significantly affected by nitrogen doses and plant densities. Our results indicated that suitable nitrogen dose and plant density were 180 kg N ha¹ and 88 000 plants ha¹ for popcorn grown as a second crop in Hatay ecological conditions in Eastern Mediterranean region of Turkey.

QTL Analysis of Yield-related Traits using an Advanced Backcross Population Derived from Common Wild Rice (<em>Oryza rufipogon</em> L)

Wild rice ( Oryza rufipogon L) is recognized as an important germplasm that has abundant genetic diversity and specific characters. Many of rice breeders attempt to utilize elite wild rice for rice genetic improvement and breeding program to broaden genetic background of cultivating rice. Although There are some reports that wild rice germplasms were successfully applied in rice breeding program, it is definitely depend on what we understand the traits in particular complex traits. In this research the goal was to identify alleles for yield and yield related components. An advanced backcross BC 3 population was generated by a cross between recurrent parent named Yuexiangzhan and donor parent named G52-9, a wild rice collected in Gaozhou of Guangdong . This population was evaluated for 10 agronomic traits related to yield and yield related components. Forty three QTLs of ten traits were detected based on phenotypic data in this study. There are thirty eight QTLs of eight traits detected in continuing two years and thereinto nine QTLs consistently detected in two continuing years. It is also confirmed that nine QTLs mapped on the same or adjacent regions conferring the same traits by previous research. Two QTLs, qGYP-2-1 and qGYP-3-1 mapped on chromosome 2 and 3 can increase the yield of Yuexiangzhan by 40.05% and 49.04%, respectively, contributed from wild rice. Furthermore, the results show that many of detected alleles are likely associated with the trait with wild rice genetic background, which imply that Gaozhou wild rice should be used as excellent gene donor in rice breeding program.

Molecular detection of genomic regions associated with grain yield and yield-related components in an elite bread wheat cross evaluated under irrigated and rainfed conditions

Grain yield and grain weight of wheat are often decreased by water-limitation in the north-eastern cropping belt of Australia. Based on knowledge that CIMMYT lines are well-adapted in this region, a recombinant inbred line (RIL) population between two elite CIMMYT bread wheats (Seri M82 and Babax) was evaluated under water-limited environments. Fourteen productivity traits were evaluated in 192 progeny in up to eight trials. For three aggregations of the environments (all, high yield or low yield), multiple quantitative trait loci (QTL) were detected, each explaining <15% of variation. Co-location of multiple trait QTL was greatest on linkage groups 1B-a, 1D-b, 4A-a, 4D-a, 6A-a, 6B-a, 7A-a and an unassigned linkage group. Two putative QTL (LOD > 3) from Seri (6D-b and UA-d) increased grain yield and co-located with a suggestive (2 < LOD < 3) and a putative QTL for increased stem carbohydrate content (WSC), respectively; the latter QTL also co-located with a putative anthesis QTL for earlier flowering. Both QTL were detected only in high yield (>4t ha(-1)) environments. A third increased grain yield QTL (7A-a) from Babax co-located with QTL for increased grain number. Six putative QTL increased grain weight and co-located with QTL for harvest index, grains per spike and spike number. Three putative QTL for increased grains per spike co-located with strong QTL for earlier flowering, increased grain weight and fewer spikes. A group of progeny that exceeded the mean grain yield and grain weight of commercial checks had an increased frequency of QTL for high WSC, large grain size, increased harvest index and greater height, but fewer stems, when compared to low yielding (20% less), low grain weight progeny. These findings were consistent with agronomic analyses of the germplasm and demonstrate that there should be opportunities to independently manipulate grain number and grain size which is typically difficult due to strong negative correlations.

Genotype by environment interactions, stability, and heritability of seed yield and certain agronomical traits in soybean [Glycine max (L.) Merr.

This research was aimed to (1) evaluate genotypic yield performances of eight soybean genotypes, (2) determine their stability parameters and (3) estimate variance components and heritabilities of yield and yield-related traits. Eight soybean genotypes were evaluated in two locations (Mustafakemalpasa and Gorukle) of Southern Marmara Region, Turkey during two years (2000 and 2001), to identify patterns of genotype by environment interactions and their stabilities in terms of seed yield and yield-related components. Seed yield and its components are affected by plant genotype and environmental conditions. Plot data for plant height, first pod height, number of pods per plant, number of seeds per plant, number of seeds per pod, 1000 seed weight and seed yield were observed at all the four trials. There were significant differences between genotypes of one or two years at each location for all the traits. Significant differences among years or between locations were obtained in terms of all traits. Genotype x environment interactions at all the traits were highly significant. Thus the stabilities of eight soybean genotypes were different for all the traits. According to the stability parameters, none of the genotypes were stable for seed yield. Genotypes, Hodgson-78, A-3127, Ataem-1, Corsoy and SA-88 were considered as having high adaptability to good environments while Mitchell, Ataem-2 and Etae-8 adapted to poor conditions in terms of seed yield. Genetical components of variance at all the traits were highly significant. Genotype x location x year interaction variances were also found significant at all the traits except first pod height. The estimates of heritabilities with limited phenotypic variance definition were 0.14, 0.14, 0.21, 0.004, 0.13, 0.30 and 0.26 for plant height, number of seeds per pod, 1000 seed weight, first pod height, number of seeds per plant, number of pods per plant and seed yield, respectively. The heritabilities with complete phenotypic variance definition were 0.05, 0.05, 0.04, 0.003, 0.07, 0.19 and 0.20 for the same traits, respectively. Moderate or low heritabilities estimated for all the traits showed that family selection method could be used instead of individual selection in the breeding programs for improving seed yield and its components.

Agronomic trait assessment and selection for number of capsules in determinate x indeterminate crosses of sesame

Despite the progress, improved determinate (dt/dt) lines of sesame are still low yielding. Further improvement may be achieved by crossing locally adapted indeterminate cultivars with desirable determinates from a broad-based composite population. In order to test this hypothesis, 43 F_2 base populations from these kinds of crosses were generated and a distinct variability among populations was observed for seed yield and other traits. A 20% positive selection for number of capsules as the most yield-related component was applied to the pairs of determinate and indeterminate segregating in each population. Although seed yield per plant, number of capsules per plant and number of seeds per capsule were lower in determinates than indeterminates, these gaps were closed in certain crosses sharing certain 'dt/dt' parents. Despite the fact that the plants were short, days to flowering (in F_2) and days to maturity took longer in determinates. The effect of selection was not apparent in increasing mean of progeny population in F_3 for the character under selection but the determinate group had the highest coefficient of variation (CV) as a basis for further genetic gain. It was concluded that composite populations with suitable genetic backgrounds were valuable sources of 'dt/dt' segregants; recurrent breeding efforts and the modification of farming systems are all necessary in order to adopt novel characteristics like determinacy.

Studies in combining ability for economic traits in cultivated sesame (Sesamum indicum L.)

The 36 hybrids obtained by crossing 12x3 genotypes in line x tester fashion and their parents were evaluated during rabi 2003-04 for nine metric traits. Combining ability studies indicated the preponderance of non-additive gene action for all the characters except 100-seed weight and oil content. The genotypes CO 1, TMV 4, and ORM 14 might be utilized as potential parents since they possessed high per se with significant gca effects for most of the traits under study. Based on per se performance, sca effects and standard heterosis for yield and yield related components along with maturity, the five hybrids namely, CO 1 x ORM 14, TMV 4 x ORM 17, TMV 5 x ORM 17, Paiyur 1 x ORM 14 and TNAU 2030-35 x ORM 14 were identified as the best cross combinations for further exploitation.

A comparison of seed-propagated and micropropagated Amelanchier alnifolia (saskatoon): Yield and yield components in relation to crown architecture characteristics

A study of the architecture and yield components of young micropropagated and seed-propagated Smoky saskatoons over a 4-yr period revealed no differences in height, but the diameters and branchiness ratings of the seedling plants were greater. In the 3 yr of fruit harvest there were no differences in mean fruit weight or fruit number between propagation types, but there was a difference among years. The yield was considerably greater in the third year of harvest (1996), possibly reflecting the natural tendency for yield to increase as the plants develop. In all 3 yr, fruit ripening peaked in July, with most fruit harvested within about a week on either side of the peak. Although there were strong correlations between the number of infructescences and both fruit weight and fruit number, there was little difference between propagation types. There were no relationships between main-stem diameter and the weight or number of fruit that the plant bore. However, there was a positive linear relationship between yield parameters and the diameter of the shoots bearing that portion of the crop in 1994 and 1995. Although not different between propagation types, terminal shoots were longer and greater in diameter and in 1995 bore three times more fruit yield than did lateral shoots. There were no differences between propagation types in the weight of fruit per infructescence or in the mean weight (0.71 ± 0.02 g) or diameter (10.81 ± 0.11 mm) per fruit. Key words: Fruit size, fruit number, Smoky, ripening period

Field resistance of Martonvásár winter wheat cultivars against Fusarium head blight

Fifty Triticum aestivum genotypes, including winter wheat cultivars from Martonvásár, were tested for fusarium head blight (FHB) resistance under artificially inoculated conditions. Field resistance, kernel infection, and the relative yield components (test weight, thousand kernel weight and kernel weight/heads) were examined following infection with Fusarium graminearum and F. culmorum isolates. Using data from two years, a number of Martonvásár varieties with above-average resistance to FHB were identified. On the basis of field infection, AUDPC values close to those of resistance sources were calculated for the variety Mv Emese, while 67.5% of the varieties tested had values which did not differ significantly from those of the control variety Arina. The yield components examined were modified substantially by artificial FHB infection. The thousand kernel weight and test weight of the variety exhibiting the greatest degree of infection were only 21.14% and 25.58%, respectively, of the untreated control. In one case the decline in the kernel weight/head was more than 90%. The results of multivariable statistical analysis indicated that among the Hungarian wheat genotypes, Bánkúti 1201, B9086-95 (a line derived from Bánkúti 1201), Mv Emese, Martonvásári4 and Mv Táltos could be grouped with the best sources of resistance. The experimental data revealed wide genetic variability for FHB resistance in the Martonvásár breeding stock.

Effects of Removal of Some Photosynthetic Structures on Some Yield Components in Wheat

Anakara Üniversitesi Ziraat Fakültesi Tarla Bitkileri Bölümü deneme tarlalarında 1999-2001 yıllarında yapılan çalışmada; iki ekmeklik buğday Gerek-79 ve Gün-91 çeşidinde başaklanma döneminde, kılçık, bayrak yaprak ve bayrak yaprak altındaki yaprağın uzaklaştırılmasının bazı verim öğelerine etkisi araştırılmıştır. Deneme tesadüf blokları bölünmüş parseller desenine göre dört tekrarlamalı olarak yürütülmüştür. Elde edilen sonuçlara göre; kontrole karşılaştırıldığında bayrak yaprağı uzaklaştırılan bitkilerde; başakta dane sayısı, başakta dane ağılığ ve bin dane ağırlığında her iki yılda da yaklaşık olarak sırasıyla % 13, % 34 ve % 24 oranında azalma ve protein içeriğinde % 2.8 artış ortaya çıkmıştır. Bu öğelerdeki azalma ve protein oranındaki artış kılçığı ve bayrak yaprak altındaki yaprağı alınan bitkilerde de önemli bulunmuştur

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.