Showing papers in "Crop Science in 1990"

Additive main effects and multiplicative interaction analysis of two international Maize cultivar trials

Abstract: The methodology used by the International Maize and Wheat ImprovemenCt enter (CIMMYTto) develop and improvei ts maize (Zea mays L.) germplasmin volves evaluation of families or experimental varieties in extensive international testing trials. The genotype- environmenitn teraction is producedb y differential genotypic responsest o variede nvironmentacol nditions. Its effect is to limit the accuracyo f yield estimatesa ndc omplicatet he identification of specific genotypesf or specific environmentsT.h e objective of this study was to use the Additive Main effects and Multiplicative Interaction (AMMmI) ethod,w ith additive effects for genotypesa nd environmentasn dm ultiplicative terms for genotype-environmeinn-t teraction, for analyzing data from two international maize caltivar trials. Results from the first trial were: (i) predictive assessment selected AMMwIi th one principal componenatx is, (ii) AMMinI - creased the precision of yield estimates equivalent to increasing the numbero f replications by a factor of 4.30, (iii) AMMpIr ovided muchi nsight into genotype-environmenitn teractions, and (iv) AMMseIl ected a different highest-yieldingg enotyp’et han did treatmentm eansi n 72%o f the environmentsR. esults for the secondt rial weret hat predictive assessments elects the AMMwIi th none of the principal componenatx es, whichi ncreasedp recision equivalentt o increaset he numbeorf replications by a factor of 2.59.

Leaf Water Content and Gas-Exchange Parameters of Two Wheat Genotypes Differing in Drought Resistance

Abstract: (...) The leaf relative water content (RWC) and gas-exchange parameters were compared between a drought-resistant winter wheat genotype (cv. TAM W-101) and a drought-susceptible genotype (cv. Sturdy) to determine if these physiological parameters contribute to drought resistance in TAM W-101. Plants were grown under well-watered conditions in growth chambers until drought stress was imposed by limited watering of plants at anthesis or during vegetative growth (...)

Regeneration in cereal tissue culture: a review.

Abstract: This review examines the literature on successful establishment of regenerable cell cultures in the economically important cereal crops. Some of the major trends and strategies for the establishment of in vitro cultures that express totipotency are discussed as well as current approaches. It is apparent that in cereal tissue culture, not all cells express totipotency. Generally the auxin 2,4-dichlorophenoxyacetic acid (2,4-D) is critical for the production of regenerable callus; however, the addition of cytokinin can be significant. Meristematic cells from immature tissues are the targets for plant growth regulator action. Some genotypes produce embryogenic cultures, while others are recalcitrant to in vitro manipulation. Regeneration occurs either by somatic embryogenesis or adventitious bud and shoot development with subsequent rooting. In these meristematic tissues, plastids are at the undifferentiated proplastid stage of development. The development of a white, nodulated embryogenic callus in somatic embryogenesis and the formation of green buds during organogenesis suggest divergent modes of plastid differentiation during morphogenesis. Plant growth regulators may be involved with inducing or directing different pathways of plastid differentiation. Genotypic differences in morphogenesis may be due to differences in endogenous hormone levels. Technical Article no. 24703 from the Texas Agric. Exp. Stn.

Desiccation Tolerance and Its Relationship to Assimilate Partitioning in Winter Wheat

Abstract: Winter wheat (Triticum aestivum L.) is frequently subjected to stress that causes early senescence of plants and cessation of grain filling. This research evaluated chemical desiccation for selecting genotypes for tolerance to postanthesis stress and determined the relationship of chemical desiccation tolerance to carbohydrate and N partitioning. Twenty-eight cultivars with a wide range of stress tolerance and yield potential were treated with 0 and 0.19 mol L⁻¹ NaCIO₃ 14 d after anthesis. The 2-yr study was on a Eudora silt loam (coarse-silty, mixed, mesic Fluventic Hapludoll); treatments were in randomized-complete blocks with four replications. Ten cultivars representing a range of treatment responses were evaluated further at two locations on dryland and irrigated Eudora silt loam and Pratt loamy fine sand (sandy, mixed thermic Psammentic Haplustalf) in split plots with three replications. Cultivars that had high kernel weights and early release dates were generally more tolerant of chemical desiccation than cultivars with low kernel weights and recent release dates. Grain yields of chemically desiccated plants under irrigation correlated significantly with yields of untreated plants at one location but not at another location. Losses of dry matter and soluble carbohydrates, but not of N, from stems were related to grain yield response to chemical desiccation. We concluded that chemical desiccation effectively selects for postanthesis stress resistance, and that combining high carbohydrate reserves with efficient translocation to the grain should improve wheat performance in unfavorable environments. Contribution no. 88-392-J of the Kansas Agric. Exp. Stn.

Spike and Leaf Development of Sal‐Stressed Wheat

Abstract: Drought or salt stress while the shoot apex is in vegetative stage can markedly affect spike development and decrease yields of cereal grains. This study was conducted to determine the effects of salinity on shoot apex differentiation, particularly spike and spikelet development, and the number of tillers per plant on two wheat species (Triticum aestivum L. «Probred» and T. turgidum L. «Aldura»). Plants were grown in greenhouse sand cultures that were irrigated four times daily with modified Hoagland's solution. Two saline treatments with osmotic potentials (ψs) of −0.45 and −0.65 MPa were imposed beginning 4 d after planting by adding NaCl and CaCl 2 (5:1 molar ratio) to the base nutrient solution and were compared to a nonsaline control treatment at −0.05 MPa. Salt stress accelerated development of the shoot apex on the mainstem and decreased the number of spikelet primordia in both species. Terminal spikelet stage occurred 12 and 18 d (≃280 and 420 thermal units) sooner in Aldura and Probred plants, respectively, stressed at −0.65 than at −0.05 MPa. Anthesis also occurred earlier, but tillering was delayed 3 to 4 d. Compared with −0.05 MPa, ψ s of −0.45 and −0.65 MPa decreased seed yield 38 and 54 % in Aldura and 7 and 43 % in Probred, respectively. These decreases resulted from fewer spikes per plant and fewer kernels per spike. Salt stress increased the phyllochron and reduced the final number of leaves initiated on the main stem. In sum, salt stress prior to and during spikelet development significantly decreased the yield potential of individual spikes of Aldura, but not of the more tolerant Probred. Salt stress decreased the yield potential of both species most by reducing the number of tiller spikes

Photosynthesis and Productivity during High‐Temperature Stress of Wheat Genotypes from Major World Regions

Abstract: (...) objectives were to ascertain relationships and genotypic variability among single-leaf photosynthesis, thylakoid activity, and productivity during high-temperature stress at vegetative and reproductive stages. Ten genotypes from major world wheat-producing regions were grown under moderate (22/17 °C day/night) and high (32/27 °C day/night) temperatures for 2 wk as seedlings or from anthesis to maturity. Net photosynthesis, chlorophyll variable fluorescence (Fv), and productivity were measured at both stages (....)

Chromosomal location of genes for grain protein content of wild tetraploid wheat.

Abstract: The improvement of grain-protein content is an important goal of durum wheat (Triticum turgidum L.) and other wheat breeding programs. The objective of this study was to determine the chromosomal location of genes for high grain-protein content in an accession of wild tetraploid (emmer) wheat (T. turgidum L. var dicoccoides) having seeds with high grain-protein content. The method was to substitute each of the dicoccoides (DIC) chromosomes into Langdon' (LDN) durum by crossing and backcrossing with a set of LDN D-genome disomic substitution lines (...)

Genetic Diversity for Restriction Fragment Length Polymorphisms: Relation to Estimated Genetic Effects in Maize Inbreds

Abstract: Restriction fragment length polymorphisms (RFLPs) have been proposed for investigating relationships among inbred lines and predicting heterosis and performance of single-cross hybrids in maize (Zea mays L.). Such use was evaluated in 20 maize inbreds classified as first-cycle, second-cycle, good, and poor lines, and in diallel crosses within types. Eight generations (parents, F 1 , F 2 , F 3 , backcrosses, and backcrosses selfed) from 67 crosses were evaluated for grain yield in five Iowa environments. Genetic effects were estimated from generation means by ordinary diallel analyses and the Eberhart-Gardner genetic model (...)

Field Drought Tolerance of a Soybean Plant Introduction

Abstract: (...) The objective of this study was to compare the relative drought tolerance of plant introduction PI 416937, a visually slow-wilting accession, with that of «Forrest», a popular cultivar of similar maturity. Leaf water potential (ψw), solute potential (ψ s ), and relative water content (RWC) of these genotypes were measured under two levels of soil water adjustment (well-watered and water-stressed at early pod-fill) during 2 yr in the field (on a Varina loamy sand, a clayey, kaolinitic, thermic Plinthic Paleudult (...)

Membrane Thermostability and Heat Tolerance of Spring Wheat

Abstract: Spring wheat (Triticum aestivum L.) is a major crop of the northern Great Plains. High temperature stress during the grain-fill period is a major constraint to increased productivity of spring wheat, particularly in the southern part of the region. The electrolyte leakage or membrane thermostability (MT) test was conducted at anthesis on flag leaves of eight field-grown genotypes of spring wheat and the results related to the yield of those genotypes grown at three other field locations. Genotypes were derived from two crosses involving parents adapted and unadapted to the region or thermal aspects of the climate. The three field locations represented northern, central, and southern areas of the northern Great Plains with soil classifications of Aeric Calciaquoll, Aeric Calciaquoll, and Typic Haplustoll, respectively. Based on MT values, genotypes were grouped as heat-tolerant (HT, n = 4) vs. heat-sensitive (HS, n = 4). The HT and HS genotypes produced similar grain yields at the northern and central locations. However, the HT group of genotypes produced 21% more grain yield (4.28 Mg ha⁻¹) than the HS group (3.55 Mg ha⁻¹) at the southern site, which was considerably warmer during the grain-fill period than the other two locations. Average temperatures during July were 19.5, 21.7, and 23.4 °C at the northern, central, and southern locations, respectively. Based on results of this study it seems that the MT test is a useful screening procedure for selecting HT genotypes of spring wheat. Joint contribution Colorado Agric. Exp. Stn. and Pioneer Overseas Corp.

Carbon Isotope Dicrimination: Potential in Screening Cool-Season Grasses for Water-Limited Environments

Abstract: (...)Significant variability for carbon isotope discrimination (Δ) was detected among the clones for the two peak-season harvests, but not for the late-season harvest in 1986. Broad-sense heritabilities for Δ were generally greater at the high and intermediate water applications than at the low water application and coefficients of variation for Δ were typically less than 4.5%. Selection for Δ appears to be a promising screening tool for the development of crested wheatgrass populations that are productive and make efficient use of limited water resources

Selecting oat lines for yield in low-productivity environments

Abstract: Cultivars for use in low-productivity environments (LPE) can be selected directly, in LPE, or indirectly, in medium- or high-productivity environments (MPE or HPE, respectively). These contrasting strategies were compared by means of predictions and an empirical selection experiment in which random populations of oat lines were selected for grain yield in LPE, MPE and HPE; selected lines were then evaluated at each productivity level. The influence of replication (across environments) of the selection unit on the relative effectiveness of direct and indirect selection for yield in LPE was also examined. At low levels of replication, the greatest predicted and realized response in LPE resulted from selection in MPE. However, when replication was increased, direct selection was more effective. A positive correlation between degree of replication and the relative effectiveness of direct selection in LPE is expected when heritability (h2) is greater in HPE than in LPE and when the genetic correlation (rG) between yield in HPE and in LPE is less than one. The results indicated that separate breeding programmes may result in the greatest yield gains for some low-productivity cropping systems. Estimates of h2 in HPE and LPE, and rG between yields in HPE and LPE, could be used to predict such situations

Root Growth of Winter Wheat under Elevated Carbon Dioxide and Drought

Abstract: With the atmospheric concentration of CO 2 increasing, it is important to know how this will affect crop growth The objective of this study was to determine the effect of enriched CO 2 on root growth of winter wheat (Triticum aestivum L 'Newton') under both well-watered and dry conditions The wheat was grown for 3 yr in 16 plastic chambers (121 by 92 by 168 cm) in the field under ambient CO 2 (340 μL L -1 ) and elevated levels of CO 2 (485, 660, and 825 μL L -1 ) ()

Crop effects on genetic relationships among sugarcane traits

Abstract: (...) This study 's objective was to examine crop age effects on the genetic correlations among sugarcane traits using path coefficient analysis. A population was planted in 1983 and 1984 at five locations in Louisiana. Harvest data were collected for three crops. Results indicated that cane yield (TCH) was the most important determinant of sucrose yield (SPH) and became increasingly important in determinating the SPH in older ratoon crops (r sph,tch = 0.91). Stalk number (SNO) was the primary determinant of TCH and became more important in determining TCH in older ratoon crops (r tch,sno = 0.77) (...)

Phosphorus enhancement of salt tolerance of tomato.

Abstract: () Tomato plants (Lycopersicon esculentum Mill) were grown in a greenhouse in a continuously flowing solution culture system to investigate whether P fertilization modified the detrimental effects of NaCl at low constant P concentrations similar to those in soil solutions Increasing P fertilization enhanced the tolerance of tomato plants to NaCl At 01, 10, and 10 mM P, the NaCl concentrations that reduced yields of fruit by 50% were 58,72, and 130 mM, respectively ()

Irrigation effects on plant water relations and productivity of Thompson seedless grapevines

Abstract: (...)Grape yields followed declining water availability essentially linearly over the range of available data. A 50% reduction in crop evapotranspiration resulted in a 26% yield loss. Irrigation intensities that resulted in leaf water potential > -0.9 MPa, crop water stress index 0.008 m.s -1 maintained high grape productivity. These results can be used to profit-maximize irrigation water as a production input

Grain filling in three spring wheat genotypes: statistical analysis

Abstract: (...)The relationship between grain weight and accumulated growing degree-days (GDD) from anthesis was described by a logistic equation. (...)Stepwise multivariate analysis of variance indicated that maximum grain weight was the most important parameter in characterizing the grain filling curves of the cultivars studied. (...)HY320 had the largest grains (37.0-48,2 mg) (and the) highest rate of grain filling (0.129-0.146 mg/GDD)(...)

Heat tolerance in winter wheat. I, Hardening and genetic effects on membrane thermostability

Abstract: High-temperature stress during the grain-fill period of wheat is one of the major constraints to increased production. The objective of this work was to determine the relationship between membrane thermostability (MT) and other agronomic traits of winter wheat (Triticum aestivum L.). Hardened seedlings of 137 F 5 genotypes (derived from crosses of heat-tolerant and sensitive parents) and seven cultivars were evaluated for MT and the results expressed as relative injury (RI). The same 144 genotypes were grown at three field sites in eastern Colorado and evaluated for maturity (days to anthesis), grain yield, grain volume weight, and yield components. Relative injury varied significantly (P<0.01) among the 144 genotypes, with a range of 31 to 78%. Based on RI values, the genotypes were separated into three groups: heat-tolerant (HT), intermediate (I), and heat-sensitive (HS). Accordingly, 27 genotypes were classified as HT, 71 as I, and 46 as HS. There were no differences in maturity among the three groups, indicating no association between maturity and RL. At one site, the HT group produced 9 and 19% more yield than the I and HS groups, respectively, and the trend in yield among the three groups was similar at the other two sites. Additionally, grain voluyme weight and kernel weight were greater for the HT vs. I or HS groups at all three sites. Thus, heat tolerance, as evaluated by the Mt test, was associated with grain yield and quality. These results suggest that the MT test would be a suitable procedure for selecting heat-tolerant winter wheat genotypes in a breeding program

Allelopathy and autotoxicity in alfalfa: characterization and effects of preceding crops and residue incorporation.

Abstract: Alfalfa (Medicago sativa L.) is known to be both autotoxic and allelopathic. Greenhouse and laboratory experiments were conducted to determine if WL-316 alfalfa exhibits short-term autotoxicity and long-term autotoxicity and allelopathy. Long-term autotoxicity and allelopathy of alfalfa were verified at Urbana, IL, by comparing the germination and growth of alfalfa and sorghum [Sorghum bicolor (L.) Moench] on Flanagan silt loam (fine, montmorillonitic, mesic Aquic Argiudoll) previously cropped to alfalfa (alfalfa-soil) and sorghum (sorghum-soil). Short-term autotoxicity of alfalfa was investigated by studying the effect of incorporating its roots only and both roots and shoots on the germination and growth of alfalfa in alfalfa-soil and sorghum-soil. The data were further supported by a laboratory bioassay of seedling exudate and shoot leachate of alfalfa and sorghum. Plant height and fresh weight per plant of alfalfa and fresh weight per plant of sorghum were lower on alfalfa-soil than on sorghum-soil. Germination percentages of both alfalfa and sorghum and plant height of sorghum were unaffected by the preceding crop. The two soils differed in nutrient content, but fertility was high and should not have been limiting to the growth of either crop. As a result, allelopathic/autotoxic compounds in alfalfa-soil were implicated in the growth inhibition of the two crops. Soil incorporation of fresh alfalfa roots only or both roots and shoots reduced alfalfa emergence, plant height, and dry weight per plant. Primary effects of water-soluble inhibitory compounds from alfalfa shoot appeared to be on germination and radicle elongation, the latter being apparently more sensitive than the former. Alfalfa allelopathy seems to be more severe than autotoxicity. A flow diagram describes different kinds of allelopathy and autotoxicity and various situations that verify the existence of a particular kind of allelopathy or autotoxicity

Role of carbohydrates in desiccation tolerance and membrane behavior in maturing maize seed

Abstract: Seed corn (Zea mays L.) ears harvested at seed moisture contents greater than 400 g H₂O kg⁻¹ fresh wt. (fw) are sensitive to rapid, high-temperature (45–50 °C) drying, but tolerant to low-temperature drying. A preconditioning process that precludes this injury without major moisture loss was used to study the nature of the drying damage and the role of soluble sugars in membrane stabilization during drying of two seed corn hybrids. Ears were harvested at moisture contents of 550, 450, and 400 g H₂O kg⁻¹ fw, and preconditioned at 35 °C for 6 to 48 h before drying at 50 °C. Seed germination was correlated with leachate conductivity (r = −0.79) and sugar leakage (r = −0.80) after different times of preconditioning indicating the involvement of membrane function in the damage caused by high temperature drying. Total soluble-sugar concentration decreased during preconditioning with no significant change individual monosaccharide content. The percentage composition of sucrose and a larger oligosaccharide, raffinose, increased significantly during preconditioning. The high correlations between raffinose/sucrose and warm germination, conductivity, and sugar leakage (r = 0.83, −0.80, and −0.71 for A632, and 0.89, −0.78, and −0.79 for B73, respectively) indicates the added effect of raffinose on induced protection. These results suggest that soluble-sugar compositional relationships rather than absolute content may play an important role in membrane stabilization. The presence of raffinose at certain levels also may be a key factor in protecting maturing seeds from high temperature drying damage. The results also indicate that the transition from desiccation intolerance to tolerance is metabolic and not necessarily related to moisture loss. Journal Paper no. J-13479 of the Iowa Agric. and Home Economics Exp. Stn., Ames Project no. 2526.

Photosynthetic Carbon Production and Use by Developing Cotton Leaves and Bolls

Abstract: Understanding the photosynthetic C contribution of leaves to vegetative and reproductive processes is important in defining yield productivity. However, the morphological complexity of the cotton (Gossypium hirsutum L.) canopy has proven a significant barrier to establishing specific yield relationships. Therefore, a 2-yr study examined the developmental sequences of C production and utilization by leaves and bolls within the crop canopy. Photosynthesis of sympodial leaves reached a maximum just prior to anthesis of the subtended flower and tehrafter declined throughout the boll-filling period. Carbon budgets for individual sympodial leaves and their subtended bolls at mainstem Nodes 8, 10, and 12 indicated that C production was seldom synchronized with C utilization. Carbon import requirements for the first three fruiting positions at mainstem Node 10 were 50, 37, and 21%, respectively. Bolls at mainstem Node 8 collectivity required >60% import of C to sustain growth during the season. Only at mainstem Node 12 were leaves capable of supplying the total C needs of their subtended bolls. Carbon deficiencies at mainstem Nodes 8 and 10 suggested that substantial translocation of photosynthate from adjacent leaves and leaves outside the mainstem node was necessary. This was confirmed through short-term studies of 14 C-assimilate movement from leaves to developing cotton bolls. Breeding goals for improved yields through crop genetics. These simulations indicated an advantage of increased leaf longevity in the maintenance of C production

Growth responses and mineral nutrient relations of salt-stressed sorghum.

Abstract: Forage quality of alfalfa (Medicago sativa L) may be improved by increasing the proportion of leaves to stems Our objective was to examine the influence of the multifoliolate leaf trait on morphology, yield components, and forage quality of alfalfa Multifoliate plants selected for production of five, seven, or nine leaflets per leaf were compared to trifoliate plants selected for rapid (RSER) and slow (SSER) shoot elongation rate that also exhibited low and high leaf/stem ratios, respectively Herbage from field-grown plants was sampled twice in each of two years Leaves of multifoliolate plants averaged 44, 62, and 68 leaflets per leaf for phenotypes FIVE, SEVEN, and NINE, respectively In 1987 multifoliolate plants produced fewer shoots per plant (x=26) but phenotypes FIVE and SEVEN consistently produced larger shoots (x=59 shoots plant −1 , 13 g shoot −1 ) Leaf/stem ratio was lowest for phenotype RSER (063), while leaf/stem ratio of SSER (127) equalled that of phenotypes SEVEN (120) and NINE (130) In vitro dry matter disappearance (IVDMD) of herbage of multifoliolate phenotypes and SSER was greater (P<010) than that of phenotype RSER in 1986, while in 1987 IVDMD of herbage of phenotypes NINE and SSER exceeded that of RSER Herbage N concentrations of multifoliolate plants were not consistently greater than that of phenotype RSER, and were asociated with lower leaf N concentrations in multifoliolate plants The multifoliolate plants used in this study had high leaf/stems ratios, but this trait was not consistently associated with improved forage quality Environment, along with other plant characters, also influenced IVDMD and N concentrations of herbage of these plants

Seed priming influence on germination and emergence of pepper seed lots

Abstract: The seed lots that were slower to germinate had a greater response to priming, resulting in a linear relationship between the initial mean time to germination or mean time to emergence and the reduction in MTG or MTE resulting from priming. Seed priming was a simple and effective means of shortening the time from sowing to emergence of direct-seeded pepper plantings

Effectiveness of fruiting sites in cotton: yield.

Abstract: (...) Bolls at position one on sympodial branches produced 66 to 75% of total yield; those at position two produced 18 to 21%; all other positions on sympodial branches produced from 2 to 4%. Monopodial branches produced from 3 to 9%. Sympodial branches from Nodes 9 through 14 produced the bulk of the lint in all cultivars. Distribution of lint over sympodia among cultivars was significantly different for positions one and two.(...) This research provides valuable information needed to more effectively manage the production of the newer, early maturing cultivars of cotton presently being grown in the mid-South

Engineering of Herbicide-Resistant Alfalfa and Evaluation under Field Conditions

Abstract: The recent development of gene transfer systems for higher plants and progress in identifying genes encoding important agronomic traits have opened new possibilities for improvement for crop species. Our objectives were to establish a transformation procedure for alfalfa (Medicago sativa L.) line RA-3 using Agrobacterium-mediated T-DNA transfer on stem and petiole discs, compare the applicability of three selectable marker genes, and introduce a trait conferring resistance to a broad-spectrum herbicide (...)

Selection of stable cultivars using a safety-first rule.

Abstract: The presence of genotype by environment interaction is of major concern to plant breeders, since large interactions can reduce gains from selection and complicate identification of superior cultivars. Numerous statistics have been proposed to characterize stability of cultivars, yet none of these methods explicitly indicate how stability may be combined with mean yield in choosing superior cultivars. It is assumed that the plant breeder prefers a cultivar with a small probability of low yield. Using a decision-theory concept known as safety-first to model such behavior, an index incorporating mean yield and stability is developed for each of four different definitions of stability. Data from an international experimental maize (Zea mays L.) yield trial are used to illustrate the application of these indices when genotype by environment interaction is present. It is concluded that safety-first selection indices can be useful to plant breeders when genotype by environment interaction is large and poor yield has severely adverse consequences.

Frequency of 1RS.1AL and 1RS.1BL Translocations in United States Wheats

Abstract: Translocations of the short arm of rye (Secale cereale L.) chromosome 1R in wheat (Triticum aestivum L. em Thell.) offer several resistance genes, and possibly increase yield, but adversely affect bread-making quality. The objective of this study was to determine the frequency of such translocations in wheats bred in the USA. Two hundred and seven entries in six major 1989 wheat nurseries and 30 entries in the 21st International Winter Wheat Performance Nursery were cytologically screened using C-banding (...)

Growth, Morphological, and Chemical Component Responses of Tall Fescue to Acremonium coenophialum

Abstract: (...) The objectives of this study were to determine variability in responses of tall fescue genotypes to endophyte infection for select growth characteristics, plant morphology, and chemical components. Five genotypes of tall fescue were grown in both endophyte-infected (EI) and noninfected (NI) forms in the greenhouse under different clipping treatments. Tiller and dry matter production, crown depth, and total nonstructural carbohydrates (TNC) were measured (...)

Nitrogen fertilization of direct-seeded flooded vs. transplanted rice. I, Nitrogen uptake, photosynthesis, growth, and yield

Abstract: Direct-seeded flooded rice (Oryza sativa L.) culture is becoming an increasingly popular alternative to transplanting in some regions of Asia. Two field studies were therefore conducted to compare the growth patterns of wet-row-seeded and transplanted IR64 rice as affected by rate of N fertilizer application (0 and 90 kg N ha −1 in 1987 and 0, 30, 60, 90, 120, and 150 kg N ha −1 in 1988). Row-seeded rice exhibited faster crop establishment and a more productive vegetative growth phase, because transplanting shock was absent and tiller number greater. Leaf area index was greater in row-seeded than in transplanted rice. During the reproductive and ripening stages, lower foliar N concentration depressed canopy CO 2 assimilation and crop growth rate of row-seeded rice. Lower foliar N concentration was caused by dilution and not by reduced uptake. Greatest grain yield was 9.0 Mg ha −1 with 120 kg N ha −1 applied in transplanted rice and 150 kg N ha −1 in row-seeded rice. Yield response to applied N was significant up to 60 and 90 kg N ha −1 in transplanted and row-seeded rice, respectively. The harvest index was lower in row-seeded than in transplanted rice at all N rates. Row-seeded rice had a higher N demand and an inferior ability to convert high biomass production into grain yield as compared with transplanted rice. Alternative genotypes with reduced tillering ability and limited leaf area production during the reproductive stages may improve the performance of tropical wet direct-seeded rice

Condensed Tannin Concentraton in Sericea Lespedeza as Influenced by Preservation Method

Abstract: (...) The effect of forage preservation method on condensed tannins was studied in a randomized-block field experiment with high-tannin (HT) and low-tannin (LT) sericea lespedeza, Lespedeza cuneata (Dumont) G. Don. Plants were harvested and fresh frozen (FF), oven dried (OD), freeze dried (FD), and sun cured (SC). Tannin concentrations were determined with a modified vanillin-HCl procedure. To improve the vanillin-HCl assay several parameters were examined. (...)