Showing papers in "Crop Science in 1994"

Molecular Markers Associated with Maize Kernel Oil Concentration in an Illinois High Protein × Illinois Low Protein Cross

Abstract: The Illinois Long Term Selection Strains offer a unique opportunity to investigate the quantitative genetic basis of kernel chemical traits. This study was conducted to determine the number and magnitude of quantitative trait loci (QTL) influencing kernel oil concentration and kernel weight in a maize (Zea mays L.) population derived from a cross of Illinois High Protein (IHP) × Illinois Low Protein (ILP). The parental strains had been divergently selected for protein concentration for 76 cyles, yet varied in oil concentration from 29 g kg -1 (ILP) to 54g kg -1 (IHP) and in 300 kernel weight from 76.5g (ILP) to 41.1g (IHP) [...]

Antioxidant response to NaCl stress in salt-tolerant and salt-sensitive cultivars of cotton

Abstract: The mechanism(s) importing salt tolerance to plants remains unresolved. Although cotton (Gossypium hirsutum L.) is classified as salt-tolerant plant, variation in salt tolerance has been observed among different cultivars. The purpose of this study was to determine if more salt-tolerant cultivars contain higher constitutive or inducible levels of antioxidants than more salt-sensitive cultivars. Greenhouse-grown salt-tolerant (cv. Acaia 1517-88 and Acala 1517-SR2) and salt-sensitive (cv. Deltapine 50 and Stoneville 825) cotton plants treated with either 0 or 150 mM NaCl were analyzed for differences in growth and antioxidant capocities. The 150 mM NaCl treatment resulted in more than 40% reduction in growth of Deltapine 50 and Stoneville 825 and less than 30% reduction in the Acala cultivars. The more salt-tolerant cultivars had higher constitutive levels of catalase (121-215%) and u-tocopherol (312-420%). The salt treatment resulted in a 38 to 72% increase in peroxidase activity and a 55 to 101% increase in glutathione reductase activity in the Acala cultivars while the activities of these enzymes remained constant or decreased in the more sensitive cultivars. The Acala cultivars also exhibited a lower oxidized/reduced ascorbic acid ratio and a higher reduced/oxidized glutathione ratio than the more sensitive cultivars when grown at 150 mM NaCl. When subjected to a one-time salt treatment, lipid peroxidation in Deltapine 50 increased 51% over Acala 1517-88. These data indicate that protection from oxidative damage by higher levels of antioxidants and a more active ascorbate-glutathione cycle may be involved in tbe development of salt tolerance in cotton. Louisiana State Univ. in Shreveport and Louisiana State Univ. Agric. Center, Red River Res. Stn. Approved for publication by the Director of the Louisiana Agric. Exp. Stn. as manuscript no. 93-84-7172. Financial support was provided in part by Cotton Incorporated contract no. 91-723.

Remobilization of carbon and nitrogen in wheat as influenced by postanthesis water deficits

Abstract: Preanthesis stored C and N in wheat (Triticum aestivum L.) are important in a mediterranean climate because grain filling frequently depends on the remobilization of preanthesis assimilates. We determined the effect of the rate of development of postanthesis water deficits on the remobilization of C and N to the grain using stable isotopes of C and N accumulated in the plant during the vegetative phase. Plants were grown in pots with adequate water and under similar temperature and humidity conditions until anthesis, and then were transferred to two temperature and humidity regulated greenhouses, and watering was stopped. One greenhouse was maintained at minimum relative humidity of 80% and the other at 40%

Prediction of maize single-cross performance using RFLPs and information from related hybrids

Abstract: Methods for predicting hybrid yield would facilitate the identification of superior maize (Zea mays L.) single crosses. Best linear unbiased prediction of the performance of single crosses, based on (i) restriction fragment length polymorphism (RFLP) data on the parental inbreds and (ii) yield data on a related set of single crosses, was evaluated. Yields of m single crosses were predicted as y M =C V -1 y p , where: y M =m×1 vector of predicted yields of missing (i.e., no yield data available) single crosses; C=m×n matrix of genetic covariances between the missing and predictor hybrids; V=n×n matrix of phenotypic variances and covariances among predictor hybrids; and y p =n×1 vector of predictor hybrid yields corrected for trial effects (.)

Identification of Quantitative Trait Loci Using a Small Sample of Topcrossed and F4 Progeny from Maize

Abstract: Plant breeders have an interest in the identification of genomic regions associated with the expression of quantitative traits because they recognize that such information coud be used to improve realized heritability and reduce time per cyle of selection. The development of molecular marker technologies may provide tools to accomplish these goals. Maize (Zea mays L.) breeders develop new inbred parents of hybrids through topcrossed and per se evaluation of numerous quantitative traits in segregating progeny from planned breeding crosses [...]

Water-use efficiency and carbon isotope discrimination in peanut under water deficit conditions

Abstract: Because of its relationship with water-use efficiency (W), carbon isotope discrimination in leaves (Δ) was proposed to be useful for identifying genotypes with greater water-use efficiency. In this study we examined the relationship between W and Δ in four peanut (Arachis hypogaea L.) genotypes. The genotypes were grown in and around mini-lysimeters embedded in soil and were subjected to two drought regimes, intermittent and prolonged water deficit conditions, by varying the irrigation timing and amount. Automated rain-out shelters prevented any rain from reaching the experimental plots during the treatment period. The mini-lysimeters allowed accurate measurement of water use and total dry matter (including roots) in a canopy environment. Water-use efficiency, which ranged from 1.81 to 3.15 g kg−1, was negatively correlated with Δ, which ranged from 19.1 to 21.8%. Tifton-8 had the highest W (3.15 g kg−1) and Chico the lowest (1.81 g kg−1, representing a variation in W of 74% among genotypes. Variation in W arose mainly from genotypic differences in total dry matter production rather than from differences in water use. It is concluded that δ is a useful trait for selecting genotypes of peanut with improved W under drought conditions in the field. A strong negative relationship existed between W and specific leaf area (SLA, cm3 g−1) and between Δ and SLA, indicating that genotypes with thicker leaves had greater W. SLA could therefore be used as a rapid and inexpensive selection index for high W in peanut where mass spectrometry facilities are not available.

Nitrogen Response of Leaf Photosynthesis and Canopy Radiation Use Efficiency in Field-Grown Maize and Sorghum

Abstract: The grain yielding capability of maize (Zea mays L.) and sorghum [Sorghum bicolor (L.) Moench] is dependent on the capacity of the crop to assimilate CO 2 . Carbon dioxide assimilation can be measured directly at the leaf level (C A ) and indirectly at the canopy levels by determining radiation use efficiency (RUE). Since leaf N content per unit leaf area (LN) was expected to influence both of these measures of CO 2 assimilation, the primary objective of this study was to obtain field data on C A and RUE in response to differing LN induced by varying the amount of applied N fertilizer [...]

Genetics of Maize Tolerance of Striga hermonthica

Abstract: A parasitic weed, Striga hermonthica (Del) Benth, infects millions of hectares of arable land in sub-Saharan Africa, and it threatens production of cereal crops The objectives of this study were to investigate inheritance in maize (Zea mays L) inbred lines of tolerance and resistance to S hermonthica, based on visible host plant symptoms and Striga emergence counts A diallel cross involving 10 inbreds was tested under Striga infested fields at Mokwa, Nigeria, for 5 yr Host plant response was rated on a scale of 1 (no symptoms) to 9 (plants dead or dying) []

Complementary Gene Interactions in Alfalfa are Greater in Autotetraploids than Diploids

Abstract: Greater complementary gene interaction in autotetraploid alfalfa (Medicago sativa L., 2n=4x=32) may explain differences in vigor and breeding behavior between diploids and autotetraploids. Complementary gene interaction is nonallelic gene interaction or epistasis where dominant alleles at heterozygous loci may complement each other by masking recessive alleles at respective loci. This paper describes how tetrasomic segregations of linkage blocks in linkage disequilibrium produce tetraploid individuals and populations with greater complementary gene interaction than is possible at the diploid level

Diversity of Historically Important Sweet Corn Inbreds as Estimated by RFLPs, Morphology, Isozymes, and Pedigree

Abstract: Historical records indicate that sweet corn (Zea mays L.) germplasm is largely derived from the Northern Flint race of corn. In addition, most of the publicly available inbreds were derived from three cultivars: «Stowell's Evergreen», «Country Gentleman», and «Golden Bantam». In order to better understand sweet corn germplasm, 43 historically important sweet corn inbreds and three dent corn inbreds were examined by pedigree information, restriction fragment length palymorphisms (RFLPs), isozyme markers, and morphological traits. Data sets were developed from 71 RFLP probes, 17 isozyme loci, 14 morphological traits, and pedigree coefficients of relationship, and these data sets were subjected to cluster analysis (.)

Sowing date and maize productivity: I. Crop growth and dry matter partitioning

Abstract: Changes in the environment that are associated with different sowing dates can be expected to alter maize (Zea mays L.) growth and development in temperate regions. The objective of this work was to study the effect of sowing date on growth and dry matter partitioning of maize crops grown without water and nutrients limitations. A commercial hybrid (DK636) was grown in the field at four sowing dates (mid-September through mid-December) for 3 yr [...]

Silicon Concentration, Disease Response, and Yield Components of Rice Genotypes Grown on Flooded Organic Histosols

Abstract: On silicon-deficient soils, fertilization with silicon (Si) has reduced disease severity and increased yield of rice (L.). Breeding rice genotypes with greater Si concentration has been proposed, and some African and Asian rices have been evaluated for variability of Si concentration on upland and flooded mineral soils. This experiment investigated the variability and relation of Si concentration in rice plant tissue with disease severity and yield components of selected U.S. rice genotypes grown on flooded organic soils. Ten rice genotypes were grown at two Florida locations on Si-deficient organic Histosols. Plots were replicated five times in each of two Si treatments: Siamended soil with silicon added at 2 Mg ha, and an unamended control. Plots were rated for disease severity at growth stage 8 to 9 (dough to mature) and sampled for determination of Si concentration in plant tissue (leaves and straw). Genotypes differed for Si concentration and disease severity at each location and for each Si treatment. Among genotypes, disease severity was negatively correlated with Si concentration in plant tissue. Increases in yield with added Si were attributable to a greater number of grains per panicle, whereas weight per 100 seed and panicles per square meter exhibited less change. Results indicated that although Si concentration varies among genotypes and is negatively correlated with disease severity, the strength of this association is mitigated by other genotypic factors which also affect response to disease.

RFLP mapping in maize : quantitative trait loci affecting testcross performance of elite european flint lines

Abstract: The dissection of quantitative traits into their underlying Mendelian factors has become possible with the aid of molecular markers. In this study, we mapped and characterized quantitative trait loci (QTL) affecting testcross performance of maize (Zea mays L.) and discussed the consistency of these QTL across environments and testers. Two homozygous flint inbred lines were crossed to produce 380 F 2 individuals which were genotyped at 89 restriction fragment length polymorphism (RFLP) marker loci. By selfing the F 2 plants 380 F 2 lines were produced and subsequently crossed to two diverse dent inbred testers (T1 and T2). Each series of testcrosses (TC) was evaluated in field trials with two replications in four environments

Water status and development of the maize endosperm and embryo during drought

Abstract: Drought during grain filling decreases final kernel mass in maize (Zea mays L.). Lack of assimilates or an unfavorable water status within the embryo or endosperm could limit kernel development. To test these possibilities, remobilization of reduced C and N as well as kernel and embryo water status were measured in plants exposed to a water deficit during grain fill. Irrigation was withheld from fieldgrown plants after final kernel number was established. This treatment resulted in a soil moisture deficit of 224 mm and decreased endosperm and embryo mass by 16%, compared with controls. The water deficit shortened the effective filling period, but did not alter the rate of dry matter accumulation in either the endosperm or embryo

Removing Spatial Variation from Wheat Yield Trials: A Comparison of Methods

Abstract: Most cultivar evaluation trials use blocked designs and are analysed using classical analysis of variance; however, a standard analysis for blocked designs often does not adequately account for spatial variability. Recent advances in spatial statistics suggest that there are better alternatives. The primary objective of this research was to compare randomized complete block (RCB) analysis with two nearest neighbor adjustment (NNA) methods; a random field procedure was also examined, as another way to remove spatial variability. Yield data from three replicated breeding nurseries involving diverse adapted and unadapted germplasm, each grown at four locations in Nebraska during 1988-1989, were used for the comparisons

Leaf rust-resistance genes Lr41, Lr42, and Lr43 transferred from triticum tauschii to common wheat

Abstract: In order to diversify the genetic base of resistance in hard red winter wheat (Triticum aestivum L.) to leaf rust (caused by Puccinia recondita Rob. ex Desm.), five genes for resistance were transferred from the diploid goatgrass T. tauschii (Coss.) Schmal. to hexaploid wheat lines. One of the derived lines, KS90WGRC10, had a very low infection type when inoculated with 23 cultures of P. recondita. The others, KS91WGRC11, KS92WGRC16, U1865, and U1866, had low to intermediate infection types with three cultures

Stability of the relationship between specific leaf area and carbon isotope discrimination across environments in peanut

Abstract: In previous experiments,s pecific leaf area (SLA)w ass hownto be correlated with both carbonis otope discrimination( A) and water use efficiency in peanut( Arachis hypogaeaL .) suggesting that SLAc an be usedt o screen genotypesfo r W.H oweverv,e ry little information is available on the stability ofthe relationship between SLA and A across environmentsT. hep resent study was conducted to examine genotype × environment (G × E) interaction for the relationship betweenS LAa nd A. Four peanutg enotypes (Chico, McCubbinS,h ulamit, and Tifton-8) with contrasting carbon isotope discriminating characteristicsw ereg rownin the field either undera dequatelyir rigated or rainfed conditionsa t two locationsi n QueenslanAd,u stralia. Thes easonalc hangesi n A and SLAw ere examinedb y samplingl eaves at monthly intervals. The values of A and SLA were significantly influenced by the location, genotype, and irrigation treatments. Genotype × location interaction effects on the relationshipb etweenA and SLA were not significant. The positive relationship between SLA and A was maintained whend ata werec ombinedov er sites and treatments (r~ = 0.87, P < 0.01) indicating stability of the relationship across environments. The SLA was negatively correlated with nitrogen content per unit leaf area (SLN) which in turn was negatively correlated with A. The results suggested that SLA can be used as a surrogate for A.

DNA marker analysis of loci underlying resistance to soybean cyst nematode (Heterodera glycines Ichinohe)

Abstract: Inheritance of resistance to soybean cyst nematode (SCN, Heterodera glycines Ichinohe) is oligogenic and complex. DNA markers, such as restriction fragment length polymorphisms (RFLPs), can be used to identify loci associated with complex genetic characters, including SCN resistance. To uncover these associations, 56 F 2 lines from a cross between a susceptible (M83-15) and a resistant (M85-1430) soybean [Glycine max (L.) Merr.] inbred line were mapped for DNA marker polymorphisms. F 3 lines derived from these F 3 individuals were assayed for SCN disease response in the greenhouse to a field isolate of SCN from Minnesota that tested as Race 3. The F 2 genotypic classes for each of 43 DNA markers were then contrasted with SCN disease response to identify marker loci associated with SCN resistance

Relationships among European Barley Germplasm: I. Genetic Diversity among Winter and Spring Cultivars Revealed by RFLPs

Abstract: Restriction fragment length polymorphisms (RFLPs) have been proposed for characterizing genetic diversity of barley (Hordeum vulgare L.) germplasm. Forty-eight (24 winter, 24 spring) cultivars from the European barley germplasm were assayed for RFLPs with 136 clone-enzyme combinations (CEC) (48 DNA clones, three restriction enzymes). Objectives of this study were to (i) assess the amount variation for RFLPs in these materials, (ii) determine RFLP-based genetic similarity estimates between unrelated cultivars within and between the winter and spring barley germplasms, and (iii) examine the usefulness of RFLPs for classification of cultivars from different germplasm pools. Thirty-five DNA clones detected polymorphism with at least one enzyme. For the 62 polymorphic CEC, 58% of all RFLP patterns were common to both winter and spring barley, and about 20% were specific to the cultivars of each group. Genetic similarity (GS) calculated from RFLP data ranged from 0.64 to 0.93 between unrelated pairs of cultivars. Mean GS (MGS) for unrelated cultivar combinations within the group of winter (0.85) and spring (0.84) type cultivars were significantly greater than for winter × spring cultivar combinations (0.76). All winter and spring cultivars except two had a smaller MGS to cultivars from the other group than to unrelated cultivars from the same group. Principal coordinate analysis of GS estimates resulted in a separate grouping of winter and spring cultivars; further subgroups were also apparent for cultivars with a similar pedigree background. Results from our study corroborate the usefulness of RFLPs for the organization of elite barley germplasm.

Sowing date and maize productivity: II. Kernel number determination

Abstract: Kernel number in maize (Zea mays L.) depends on the physiological conditions of the crop at flowering. Our objective was to study the effect of sowing date on the relationship between crop growth rates in the 4-wk-period bracketing silking and the components of final kernel number. A commercial hybrid (DK636) was grown in the field at four sowing dates (mid-September, mid-October, mid-November, and mid-December) for 3 yr at INTA Balcarce Experimental Station, Argentina, at a density of 8.6 plants m -2 , without water and nutrients limitations [...]

Water Stress and the Water Relations of Seed Development: A Critical Review

Abstract: Water availability plays a major role in the regulation of seed development. Experimental evidence on the water relations of seed development is reviewed, with emphasis on the measured water potential values of well-watered and water-stressed seed, fruit, and leaf tissues. The hypothesis of hydraulic isolation of developing seeds from the water relations of the maternal plant, proposed on the basis of the maintenance of measured water potential (ψ w ) differences between these tissues, is examined and found to be problematic. Apparent ψ w gradients have also been recorded for seeds developing within fleshy fruits or in vitro on defined medium, where hydraulic barriers would not be present (.)

Comparison of Related Wheat Stocks Possessing 1B or 1RS.1BL Chromosomes: Agronomic Performance

Abstract: The 1RS.1BL translocation is widely used by wheat (Triticum aestivum L.) breeders to enhance agronomic peformance and particularly grain yield. Research is lacking that compares agronomic trait expression in closely related stocks with or without the translocated chromosome arm. Our objective was to determine the effects of 1RS.1BL on means and genetic variances for grain yield and other agronomic traits in two hard red winter wheat populations segregating for the «Aurora» translocation. Two field experiments were conducted using different genetic materials derived from two crosses, OK83398 × «Chisholm» and OK83398 × «Arkan». In Experiment 1, 25 pairs of F 5 -derived near-isolines homozygous for either 1B or 1RS.1BL were evaluated in three environments [...]

Plant Spacing and Reflected Far‐Red Light Effects on Phytochrome‐Regulated Photosynthate Allocation in Corn Seedlings

Abstract: Allocation of photosynthate among leaves, stems, and roots is critical in seedling establishment. Corn (Zea mays L.) seedlings were grown in different spacing patterns in a field and with different reflected far-red (FR) to red (R) light ratios to test the effects of a modified FR/R ratio on photoassimilate allocation. Green leaves absorbed most of the R and reflected much of the FR. Therefore, close-spaced plants received more reflected FR and higher FR/R ratios. Seedlings that received the higher FR/R ratios developed longer and narrower leaves, longer stems, and less massive roots. Stem elongation was an early response to increased FR/R ratio even though light did not impinge directly on the stems, which were initially at or below the soil surface and covered by several layers of leaves. Row orientation did not significantly alter FR/R ratio or seedling morphology because corn leaves are not heliotropic and did not function as directional FR reflectors, as was observed for soybean [Glycine max (L.) Merr.] in a previous study [...]

Leaf Gas Exchange Parameters Vary among Cotton Genotypes

Abstract: In trying to increase the yield of upland cotton (L.), breeders have indirectly selected more for increases in harvest index than in photosynthesis. Future cotton yield advances may need increases in both harvest index and photosynthesis. The objectives of this study were to determine if differences in leaf CO-exchange rate (CER) existed among cotton genotypes, investigate physiological mechanisms for the gas exchange differences, and determine if gas exchange parameters were related to genotypic lint yield variability. Field studies were conducted from 1990 to 1992 on 18 cotton genotypes. Leaf CER, chlorophyli.(Chl) concentration, soluble protein concentration, specific leaf weight (SLW), lint yield, and yield components were determined each year. In addition, Chl fluorescence measurements were made in 1992. The CER of the 18 genotypes significantly varied about 10% from a low of 26.0 μmol m s to a high of 28.8 ltmol m s. DES 119 and MD 51 ne had higher CER, whereas the CER of Dixie King and Stoneviile 508 were lower. The genotypes differed in leaf Chl and soluble protein concentration in both 1991 and 1992. The CER was positively correlated with leaf Chl concentration (= 0.768*) and SLW (= 0.568*) in 1991. No difference in the Fv/Fm parameter of Chi fluorescence was found among the genotypes in 1992. A significant positive association (= 0.205**) was found between lint yield and CER during the boll filling period in 1990 and 1991. CER was positively associated with fiber micronaire (= 0.772*) and fiber maturity (0.797*) in 1992. As some cotton breeders bred for higher yielding genotypes, they may have inadvertently selected for increased photosynthesis.

Cytogenetically monitored transfer of powdery mildew resistance from rye into wheat.

Abstract: Powdery mildew, caused by the fungus Erysiphe graminis DC. ex Merat f. sp. tritici Em. Marchal, is a serious disease of cultivated bread wheat, Triticum aestivum L. em Thell. About 10 powdery mildew resistance genes are known in wheat and most of them are used in cultivar improvement. However, many of these genes were overcome by the fungus and are no longer effective and therefore, new sources of resistance are continuously being sought. Recently, we reported a new source of powdery mildew resistance, preliminarily designated MIP6L, that was derived from the long arm of chromosome 6R of Secale cereale L. cv. Prolific. The aim of this study was to transfer MIP6L to a cytologically stable wheat-rye chromosome translocation [...]

Timing and Level of Nitrogen Fertility Effects on Spring Wheat Yield in Eastern Canada

Abstract: Bread wheat (Triticum aestivum L.) produced in areas of higher rainfall, such as eastern Canada, are often low in protein. Our objective was to determine if N management could be used as a way to produce bread quality wheat in eastern Canada. An experiment was conducted for 2 yr at two Quebec sites. The effects of N fertilizer level and timing on grain yield, yield components, and lodging level of four hard red spring wheat cultivars with breadmaking potential were investigated [...]

Flowering of Diverse Maize Cultivars in Relation to Temperature and Photoperiod in Multilocation Field Trials

Abstract: The accurate prediction of time to flower is important for the efficient exchange of genetic material among environments. The objective of this research was to evaluate methods of calculating thermal time for the sowing-silking interval (SSI) in a diverse group of 18 maize (Zea mays L.) cultivars, which were sown in a multilocation field trial at 53 planting date-location combinations. These ranged in mean temperature from 13.2 to 29.4 degrees C during the SSI, and in photoperiod at tassel initiation from 11.7 to 19.5 h. Thermal time computed from daily maximum (TX) and minimum temperatures with a base of 6 degrees C, an optimum temperature (To) of 30 degrees C, and a linear adjustment for supra-optimal values of TX such that TX = 30 - (TX - To), resulted in a lower coefficient of variation (CV) for thermal time across sites and cultivars (10.9%) than did other methods, though several of these methods gave similar results. The CVs for thermal duration of the SSI for cultivars adapted to temperate, lowland tropical and highland tropical environments averaged 7.8, 11.5. and 15.4% respectively. For tropically-adapted cultivars, the increase in the sowing-anthesis interval in day lengths > 13 h averaged 47 degrees Cd h-1 (range 24-100 degrees Cd h-1), while temperate cultivars were virtually photoperiod insensitive. Photoperiod sensitivity was positively correlated with the anthesis-silking interval [r = 0.62 (P = 0.01), 16 df]. This study confirms the need to determine photoperiod sensitivity and optimum temperatures for development of tropical cultivars if precise estimates of thermal time to flowering and maturity at sites with photoperiods > 13 h are required.

Pedigree Analysis of Elite Soybean Lines

Abstract: The reported genetic diversity of North American soybean [Glycine max (L.) Merr.] cultivars is low. Public and industry breeders have initiated programs to expand the diversity. This paper assesses the impact of diversification efforts on the extent and pattern of diversity among elite lines and estimates the impact of industry on diversity. Coefficient of parentage (CP) analyses were performed with 122 lines from the northern and southern regions of the USA. The average CP was 0.173: this value was 0.233 among northern lines, 0.261 among southern lines, and 0.100 between lines from different regions. These values, and an analysis of the number of ancestors and their contribution of parentage to the elite population, were similar to values in previous reports, thereby indicating that recent efforts of public and proprietary breeders have had little impact on diversity among current elite lines [...]