Northrup King Research Articles

Metabolizable Protein of Summer Annuals for Growing Calves

Two trials were conducted to determine and evaluate the rumen degradable and escape protein (EP) value of two summer annuals for yearling cattle. In Trial 1,120 heifers (Bos taurus) (530 lb), arranged in a completely randomized design, were supplemented with 0, 0.25, 0.40, or 0.55 lb crude protein (CP)/d supplied by corn gluten meal:blood meal (CGM:BM) replacing a corn starch:molasses control, keeping the supplements equivalent in energy. Heifers grazing ‘Piper’ sudangrass [Sorghum bicolor (L.) Moench] (70 d) showed a negative linear (P < 0.02) response to supplemental protein and quadratic (P < 0.10) response (1.41,1.54,1.32, and 1.14 lb/d gain, respectively). Heifers grazing Northrup King ‘Millex’ pearl millet [Pennisetum americanum (L.) Leeke] (55 d) showed a cubic (P < 0.05) response (1.01, 1.23, 1.08, 1.25 lb/d gain, respectively) which tended to be linear (P = 0.13). Cattle on pearl millet responded to supplemental protein while cattle on sudangrass did not, which is supported by high EP values of sudangrass extrusa. In Trial 2, 60 Angus heifers and 60 Angus steers (600 lb) grazing sudangrass (56 d) were allotted to (i) molasses (ii) corn starch (iii) CGM:BM at 0.25 lb CP/d (iv) corn starch and CGM:BM at 0.25 lb CP/d, or (v) CGM:BM at 0.50 lb CP/d. All five treatments contained the same amount of molasses, and corn starch provided energy equal to CGM:BM. Supplemental protein improved gains (P = 0.10) (1.10,0.99,1.14 lb/d, respectively) over the molasses control (0.84 lb/d) but did not increase gains over the corn starch (1.17 lb/d). The lack of response to supplemental EP above the corn starch is again supported by high EP values of the sudangrass extrusa. Research QuestionSummer annuals can provide alternate pastures for grazing yearling cattle during summer slump periods of cool season perennial forages. They are also an alternative crop for cultivated land less suitable (or less profitable) for other cropping systems. Summer annuals can be grazed more intensely than perennial forages because perennial stands must be maintained for subsequent years. For the summer annuals to be a viable alternative, however, they should provide high gains per acre. This can be achieved if digestibility and protein levels are adequate. The objective of Trial 1 (1989) was to determine the escape protein value of sudangrass and pearl millet for growing calves. The objective of Trial 2 (1990) was to further evaluate the metabolizable protein value of sudangrass. Literature SummaryMetabolizable protein is the combination of microbial protein synthesized from rumen degradable protein and escape protein (not degraded in the rumen and used directly by the animal). Metabolizable protein should be adequate for optimum cattle growth before the forage is a viable option. The protein requirement of rapidly growing ruminants is not met by microbial protein synthesis alone. Dietary escape protein has increased performance in growing cattle when energy and ammonia were not limiting microbial protein synthesis. The metabolizable protein value of sudangrass and pearl millet for growing calves has not been evaluated. Study DescriptionIn Trial 1, 60 heifers grazed ‘Piper’ sudangrass (70 d) and 60 heifers grazed Northrup King ‘Millex’ pearl millet (55 d). Treatments: Corn starch:molasses control at 0 lb crude protein (CP)/d Corn gluten meal:blood meal (CGM:BM) at 0.25 lb CP/d CGM:BM at 0.40 lb CP/d CGM:BM at 0.55 lb CP/d In Trial 2, 60 heifers and 60 steers grazed Piper sudangrass (56 d). Treatments: Molasses Corn starch CGM:BM at 0.25 lb CP/d Corn starch and CGM:BM at 0.25 lb CP/d CGM:BM at 0.50 lb CP/d All five treatments contained the same amount of molasses; and corn starch provided energy equivalent to that of CGM:BM. Applied QuestionDid supplemental escape protein increase gains of cattle grazing sudangrass or pearl millet? Supplemental escape protein did not increase gains of cattle grazing sudangrass. The cattle primarily ate leaves which were highly digested. The sudangrass leaves appeared to supply enough escape protein. Supplemental escape protein slightly increased gains of cattle grazing pearl millet. The pearl millet leaves were also highly digested but did not supply adequate escape protein; however, supplementation might not improve gains enough to be economical. Is metabolizable protein limiting in sudangrass? The lack of response to supplemental protein above the corn starch control and the adequate levels of rumen ammonia measured, suggests metabolizable protein is not limiting for growing calves.

Whole-plant corn, forage sorghum, and grain sorghum silages for growing cattle (1993)

Agronomic and cattle performance traits were measured for eight silages produced in 1991. The silages were: irrigated Pioneer 3377 corn; dryland (early-planted) DeKalb 535 corn; irrigated and dryland DeKalb DK 42Y grain sorghum; and dryland forage sorghums Cargill 200F, Pioneer 947, Northrup King (NK) 300, and Funk's 102F. The irrigated corn and NK 300 and Funk's 102F forage sorghums had the highest whole-plant dry matter (DM) yields per acre; early-planted corn had the lowest yield. The dryland grain sorghum had the highest grain yield and the early-planted corn, the lowest. Average daily gains (ADG) were excellent for steers fed each of the eight silage rations and reflected the relatively high grain contents of the silages and the high DM intakes (2.37 to 2.81% of body wt). As expected, the irrigated corn silage produced the fastest and most efficient gain; the late-maturing, Funk's 102F forage sorghum produced the slowest and least efficient gain.

Agronomic performance and silage quality traits of forage sorghum hybrids in 1992 (1993)

Rainfall was much above and temperature much below normal during the 1992 growing season. Both whole-plant dry matter (DM) and grain yields were excellent for all 11 hybrids. The two short, mid-maturing, forage sorghums (Northrup King 300 and Golden Harvest H-45) had the highest silage and grain yields; the early-maturing (Cargill 200F) and male sterile (Golden Harvest H-1) forage sorghums and the grain sorghum (DeKalb DK 42Y) the lowest silage yields. A storm with high winds on October 7 and 8 caused severe lodging in all six mid- and late-maturing hybrids (earlier-maturing hybrids had already been harvested). The 10 forage sorghum hybrids differed significantly in three important silage quality traits"”whole-plant DM, crude protein, and acid detergent fiber. Silage agronomic performance for four of the forage sorghums over 6 of the past 7 years is presented.

Canopy temperature as a measure of salinity stress on sorghum

A complete understanding of plant response to combined water and salinity stress is desirable. Previous growth chamber and greenhouse experiments with sorghum and maize indicate that soil salinity, by negatively affecting growth processes, may reduce consumptive water use, thus prolonging the supply of available soil moisture. In the present field experiment, canopy temperature measurements were used to examine the effect of soil salinity on the plant-soil water relations of sorghum (Sorghum bicolor L. cv. Northrup King 1580). An infrared thermometer was used to measure canopy temperature during a 9-day period including two irrigations in plots of various salinities. The salinity treatments were created by a dual line-source sprinkler irrigation system, which applied waters of different quality. Excess irrigation allowed soil moisture to be uniform across the salinity treatments at the beginning of the measurement period. Consumptive water use and soil salinity were measured to quantify the salinity and water treatments. Grain and dry matter yields provided measures of plant response. Canopy temperature measurements were sensitive enough to detect differences across the salinity treatments when soil moisture was uniform for several days following irrigation. However, over the 9-day measurement period, plants in the low-salt plots used more water than plants in the high-salt plots. This differential water use eventually offset the salinity-induced stress, with the result that temperature differences were eliminated. Differences in temperature were observed again following irrigation. The results demonstrate that canopy temperature can be used as a tool to detect salinity stress on sorghum. Timing of measurements with regard to irrigation is identified as a key factor in detecting temperature differences that can be attributed to the presence of soil salinity.

Productivity of Clay Tailings from Phosphate Mining: III. Grain Crops

AbstractPhosphatic clay is a waste product from the Florida phosphate mining industry presently totaling 41 000 ha. These clays contain no phytotoxic materials, are high in most plant nutrients, and 226Ra and average about 460 g moisture per kilogram. A split‐plot field experiment was conducted to study forage and grain yield, forage quality, plant nutrient concentrations, changes in soil nutrients, and 226Ra contents of four grain crops in various rotations. The crop rotations (i) corn (Zea mays L. ‘Jacques 247’)‐sunflower (Helianthus annuus L. ‘Cargill 205’), (ii) sunflower‐grain sorghum (Sorghum bicolor L. Moench ‘Northrup King Savanna 5’), (iii) soybean (Glycine max L. Merr. ‘Williams 80’)‐grain sorghum, and (iv) grain sorghum‐soybean ‘University of Florida V‐1’) were grown on a dry phosphatic clay with and without a 50‐mm surface layer of quartzsand tailings. Nitrogen was the only fertilizer element applied. Results show that corn and grain sorghum produced highest (P &lt; 0.05) forage yields (15.7 and 13.4 Mg ha–1) and highest grain yields (8955 and 4302 kg ha–1) per harvest, respectively. Soybean harvested for forage (Crop 1) contained the highest crude protein (217 g kg–1) and in vitro organic matter digestibility (736 g kg–1). Concentrations of P, K, Ca, Mg, and Fe in most of the forages were adequate for the diets of beef cattle (Bos taunts), while those of Mn, Cu, and Zn were low. Mehlich I‐extractable soil P (1601 mg kg–1), Ca (4696 mg kg–1), and Mg (1173 mg kg–1) were considered very high and changed little over the 4‐yr production period. Application of 50 mm of sand tailings tended to increase (P &lt; 0.05) Mehlich I‐extractable P, Ca, Mn, Cu, Zn, and Fe. Radium‐226 concentration in the forage of all grain crops averaged 8.5 Bq kg–1, which was about 17 times higher than that in the grain (0.4958 Bq kg–1) of the same crops. Concentrations of 226Ra in the forage (8.288 Bq kg–1) and grain (0.6771 Bq kg–1) were 1.1% and 0.09% of the concentration in clay (761 Bq kg–1) respectively. These data indicate that phosphatic clays can be a valuable resource for the production of corn and sorghum grain that contain low concentrations of 226Ra.

Panicle Feeding Resistance to Spodoptera frugiperda (Lepidoptera: Noctuidae) and its Relationship to Some Chemical Characteristics of Sorghum Accessions

Nineteen sorghum, Sorghum bicolor (L.) Moench, accessions were compared with the standard commercial cultivar ‘Northrup King Savanna 5’ for hard-dough stage panicle resistance to feeding by larvae of the fall armyworm, Spodoptera frugiperda (J. E. Smith). The biological variables measured to determine the differential development of S. frugiperda on diets containing florets of the sorghum genotypes were larval and pupal weight, duration of the larval stage, time to adult emergence, survivorship, fecundity, net reproductive rate, intrinsic rate of increase, and relative fitness. The plant introductions IS1340C, IS2246C, IS2403C, IS2553C, IS2569C, IS2825C, IS3477C, IS6911C, IS7007C, IS7498C, IS8337C, IS12219C, IS12592C, IS12612C, IS12617C, IS12662C, IS12664C, IS12666C, and IS12683C were all found more resistant than ‘Northrup King Savanna 5’, which is the most resistant commercial genotype available. Resistance in IS1340C, IS2246C, IS2403C, IS2553C, IS3477C, IS6911C, IS7007C, IS7498C, IS12612C, IS12662C, IS12664C, and IS12666C was primarily due to factors in the glumes (including lemmas and paleas). Chemical components in the seed were mainly responsible for resistance in IS2825C, IS12617C, and IS12683C, whereas factors in both seed and glumes were responsible for the resistance shown by IS12219C and IS12592G. Resistance was significantly correlated ( r 2 > 0.50, P < 0.05, n = 16) with the concentration of acid detergent fiber and tannin in the seed.

Panicle-Stage Resistance to Spodoptera frugiperda (Lepidoptera: Noctuidae) in Converted Sorghum Accessions

Differential developmental responses of fall armyworm, Spodoptera frugiperda (] . E. Smith), were compared after larvae were fed milk stage spikelets (complete florets) of field-grown converted sorghum ( Sorghum bleolor (L.) Moench) accessions incorporated into a meridic diet. Larvae fed diet supplemented with spikelets of ‘International Sorghum (IS) 12592 Converted (C)’ were significantly smaller compared with those fed diet supplemented with spikelets of the released resistant hybrid ‘Northrup King Savanna 5’. Feeding on diet containing the genotypes‘ISI34OC’,‘IS2246C’,‘IS2569C’,‘IS7498C’,‘IS12617C’, or ‘IS12683C’ resulted in a significantly longer duration of the larval stage of fall armyworm than feeding on diet containing the resistant check NK Savanna 5. Pupal weights of fall armyworm that were fed diet supplemented with ‘IS2403C’, ‘IS2569C’, ‘IS7498C’, ‘IS12617C’, or ‘IS12657C’ were significantly less compared with those of fall armyworm fed the resistant check. Weights of fall armyworm larvae were positively correlated with higher concentrations of crude protein (total nitrogen) in sorghum spikelets. The concentrations of lignin were inversely correlated with the duration of the larval development. When resistant and susceptible sorghum genotypes were considered separately, the concentration of tannin and the ratio of lignin/neutral detergent fiber were negatively correlated with the duration of the larval development in the resistant genotypes but positively correlated in the susceptible genotypes.

Differential Response of Corn Hybrids and Inbreds to Metolachlor

Greenhouse studies were conducted to determine the response of 200 corn hybrids and 29 inbreds to metolachlor applied at 4.5 kg ai ha−1. Both hybrids and inbreds varied in their response to the herbicide. The distribution of injury revealed a normal distribution curve with most of the hybrids having a midlevel of tolerance. Some hybrids were very tolerant, while others were quite sensitive. Laboratory studies were conducted to evaluate absorption and metabolism of14C-metolachlor for a subset of tolerant and sensitive hybrids. There was no observed difference in the product of metolachlor metabolism in the tolerant and sensitive hybrids. The observed variability in metolachlor tolerance among hybrids appeared due to differences in the amount of metolachlor absorption and metabolism and differences at the site of metolachlor action. The tolerant ‘Great Lakes 584’ hybrid absorbed significantly less14C-metolachlor than did the sensitive ‘Pioneer 3744’, while the tolerant ‘Cargill 7567’ metabolized significantly faster more14C-metolachlor than the other hybrids. The internal concentrations of available14C-metolachlor were the same for the tolerant Cargill 7567 and the sensitive ‘Northrup King 9283’ after 8 h, indicating differences at the site of action of metolachlor for these two hybrids.

Corn Hybrid‐Starter Fertilizer Interaction for Yield and Lodging

The value of placing small amounts of soluble fertilizers in close proximity to the seed at corn (Zea mays L.) planting was debated in the early 1980s for corn grown in a high‐yield environment, but is becoming an accepted practice in the southeastern USA. The objective of this study was to evaluate yield and lodging of several corn hybrids to starter fertilizer application in a high‐yield environment. Starter and no‐starter were the two fertility treatments. Starter was applied as NH4‐polyphosphate (10‐15‐0) in a band on the soil surface at planting. Rainfall was measured, and irrigations scheduled with tensiometers. Starter fertilizer significantly increased grain yields compared to no‐starter. Hybrid ✕ year and hybrid ✕ starter treatment interactions were significant. Certain corn hybrids were identified as positive changers (Funks G4733, Asgrow RX777, Sunbelt 1880, Pioneer 3320, Jacques JX247, Jacques 8400, Northrup King PX9581, and Coker 8680) that consistently yielded more with starter than others identified either as nonchangers or as negativechangers. Percent lodging generally was greater with no starter fertilizer (year ✕ starter and hybrid ✕ starter interactions were nonsignificant). Hybrid ✕ year interactions for percent lodging were significant. Certain corn hybrids (Jacques JX247, DeKalb DK748, and Jacques 8400) consistently exhibited less lodging than the hybrid mean when fertilized with a starter. The management implication is that certain corn hybrids may be profitably fertilized with a starter fertilizer but others may not, since they either do not respond (nonchangers) or respond negatively to starter fertilizer.

Assessment of the potential of the blue light gradient in soybean pulvini as a leaf orientation signal

Blue light gradients in the pulvini of soybean (Glycine max var. Northrup King S1346) leaves with different laminar orientations were examined with a fiber optic microprobe. The gradients changed markedly as a function of both incident light angle and leaf position and were determined largely by the amount of light present in the adaxial side of the pulvinus. The steepest gradient for inclined leaves was with light incident at 90° whereas for declined leaves it occurred when the light was incident at 150°. A proposed pulvinar mechanism which allows for the detection of light direction and leaf position by using the blue light gradient as an orientation signal could account for solar tracking by soybean.

Leaf Orientation of Soybean Seedlings. I. Effect of Water Potential and Photosynthetic Photon Flux Density on Paraheliotropism

Paraheliotropic (light avoiding) leaf movements can reduce transpirational water loss by lowering light interception by the leaf through action of the pulvinus. We investigated effects of plant water potential (ψw) and photosynthetic photon flux density (PPFD) on paraheliotropism in young seedlings of soybean [Glycine max (L.) Merr. cv. Northrup King S1346], The effect of paraheliotropism on leaf temperature, ψw, and stomatal conductance (ge) was determined. The angles of unifoliolate and lower trifoliolate leaves were measured for plants at a range of ψw values under different sources of illumination (sun, metal halide lamp, and fluorescent light bank) at PPFD ranging from 500 to 1600 μmol m‐2 s‐1. Leaf temperatures and gc were measured for selected plants, including those with'leaves restrained in a horizontal position. The angle between unifoliolate leaves, measured at the base of the leaves, was highly correlated with ψw. Both unifoliolate leaves and the terminal leaflets of trifoliolate leaves exhibited less paraheliotropism at a given ψw when PPFD was reduced. Paraheliotropism was associated with improved plant water status and lower leaf temperatures, but gc did not differ between paraheliotropic leaves and those restrained in a horizontal position. Paraheliotropic leaf movement and stomatal closure acted in parallel, commencing at approximately −0.4 MPa. Paraheliotropic leaf movements in soybean seedlings provide a mechanism that, with stomatal closure, can reduce transpiration under conditions of low ψw and high PPFD.

Leaf Orientation of Soybean Seedlings: II. Receptor Sites and Light Stimuli

Unifoliolate leaves of seedlings of soybean [Glycine max (L.) Merr. cv. Northrup King S1346] exhibit diaheliotropic movements when well watered and paraheliotropic movements when water stressed. The movements originate at the pulvinus at the base of each leaf lamina. The receptor site for the light stimulus was located by covering portions of the leaf surface with India ink and observing the effect on leaf movement; the leaf lamina, leaf veins, and pulvinus were tested. The pulvinus was the receptor site for light that stimulates both diaheliotropic and paraheliotropic leaf movement. The role of different wavelengths of light in diaheliotropism and paraheliotropism was determined using filters that remove broad bands of light wavelengths. Blue light was necessary for both diaheliotropism and paraheliotropism. Interference filters were used to expose soybean leaves to selected blue‐light wavelengths. The amount of diaheliotropic leaf movement at each wavelength was used to obtain an action spectrum. There was one peak between 410 nd 440 nm and one between 470 and 490 nm. A nonphytochrome photoreceptor located in the pulvinus used blue light, in conjunction with other factors, to determine leaf orientation and thereby regulate light interception of leaves of soybean seedlings.

A temperature response function for corn development

Phenological development of corn was studied under field conditions at several locations throughout southwestern Manitoba. Data for 12 location-years were collected from eight sites during 1980–1983. Two early-maturing hybrids (‘Pioneer 3995’ and ‘Northrup King 403’) and a medium maturity hybrid (‘Pride 1108’) were used. A temperature response function that accurately described phenological development under a controlled environment was modified and used to estimate phenological development of field-grown corn. The iterative temperature (IT) model allowed more accurate estimation of the duration from emergence to stem elongation and from stem elongation to silking than corn heat unit (CHU) or growing degree day (GDD) models. The IT model was independent of growth phase duration; this was not the case for CHU and GDD. The model is not suited to hybrid maturity rating, but may be useful for simulation modeling purposes.

Response of Soybean (Glycine max) Cultivars to Metribuzin in the Field and Greenhouse

Experimental objectives were to assess metribuzin tolerance of predominately privately developed soybean cultivars and to evaluate a greenhouse screening procedure. In field results in 1982, ‘Vinton 81’, ‘Northrup King 1884’ and ‘L77-1863’ soybean cultivars were extremely sensitive to metribuzin at 0.56 kg/ha, averaging 34% injury. The other 45 cultivars showed no significant injury at the 0.56 kg/ha rate, from 9 to 46% injury at 1.4 kg/ha, and 18 to 72% injury at 2.2 kg/ha. In greenhouse hydroponic studies, these same three soybean cultivars were killed, while the other 45 cultivars were injured from 15 to 82%. A good agreement of greenhouse and field data was determined, with a correlation coefficient of r = 0.82.

Differential Imazaquin Tolerance and Behavior in Selected Corn (Zea mays) Hybrids

‘Cargill 921′, ‘Great Lakes 422′, ‘Northrup King 9410′, ‘Pioneer 3901′, ‘Pioneer 3737′, and ‘Stauffer 5650’ corn hybrids were tested in the greenhouse for imazaquin tolerance. Imazaquin rates that reduced shoot growth 50%, when compared to the untreated hybrid check, ranged from 17 to 50 g/ha. When averaged together, the three most tolerant hybrids (Cargill 921, Pioneer 3901, and Great Lakes 422) were approximately one-half as sensitive to imazaquin as the three least tolerant hybrids (Northrup King 9410, Pioneer 3737, and Stauffer 5650). Studies were conducted to determine if the observed differential tolerance was caused by differences in acetolactate synthase (ALS, EC 4.1.3.18) levels and sensitivity of ALS to imazaquin. Differential imazaquin uptake, translocation, and/or metabolism were also studied as a basis for the tolerance range as was seed size and seedling growth. There were differences among hybrids in the physiological and growth parameters studied; however, these differences did not correlate with imazaquin tolerance. None of the factors studied could alone account for the differences in imazaquin tolerance.

Soybean Field Losses as Influenced by Harvest Delays

AbstractConflicts for time and machinery can postpone harvests beyond the initial time when optimum conditions exist. This study was conducted to determine the effects of delaying soybean [Glycine max (L.) Merr.) harvests on grain losses in the field. Field studies were conducted each year from 1983 to 1986 at Arlington, WI. Two cultivars from each of maturity groups (MG) 0, I, and II, one more susceptible to lodging than the other, were used. Initial harvest for each maturity group began 3 to 7 d beyond stage R8. Three additional harvests were made for each maturity group at 14, 28 and 42 d beyond their initial harvest. Average soybean field losses were 10% of the potential yield, but ranged from 5.5% in 1983 to 12.7% in 1984. Loss of potential yield increased linearly at a rate of 0.2% d−1 from an average of 6.1% at the initial harvest to 13.9% 42 d later. In 1984 and 1986 net yields were reduced 14 and 18 kg ha−1d−1, respectively. Harvest delays of 42 d resulted in plant deterioration and, in turn, lodging increased 20%, and preharvest, shatter, and stem losses increased 62, 95, and 70 kg ha−1, respectively. Shatter losses were influenced by moisture conditions at harvest, but plant deterioration also increased shattering beyond that accounted for by moisture. On the average the MG I cultivars Hardin and Northrup King S1346 lost only 7.3 and 8.3% of their potential yield versus 10.4 and 11.4% for the MG 0 cultivars Ozzie and Evans, and 10.8 and 9.2% for MG II cultivars Wells II and Corsoy 79. Both of the MG I cultivars exhibited slower rates of harvest loss increases. The proportion of potential yield lost was inversely related to potential yield, indicating that harvest efficiency was improved with higher yields. Harvest delays can ultimately result in plant deterioration, increased grain losses, increased harvesting difficulties, and reductions in net yield of 11 kg ha−1d−1.

RELATIONSHIP OF DEVELOPMENT RATES OF CORN FROM PLANTING TO SILKING TO AIR AND SOIL TEMPERATURE AND TO ACCUMULATED THERMAL UNITS IN A PRAIRIE ENVIRONMENT

The effect of temperature on the phenological development of corn (Zea mays L.) was studied under field conditions at several locations throughout southeastern Manitoba, an area where the average annual corn heat unit accumulation is in the range 2100–2500. Twelve location years of data were collected from eight sites during 1980–1983. Two early-maturing hybrids, Pioneer 3995 and Northrup King 403 and one medium maturity hybrid, Pride 1108, were used. The duration from planting to emergence (PE) was predominantly controlled by soil temperature (ST). The duration from emergence to stem elongation (ESE) was significantly related to air temperature (AT), but not to ST. For both the PE and ESE growth phases, the thermal models — corn heat units (CHU), growing degree days (GDD) and modified corn heat units (MCHU) — were better estimators of duration than calendar days. The MCHU model, with threshold temperatures of 7 and 15 °C for the response functions to daily minimum and maximum temperature, respectively, estimated the duration of ESE more accurately than did the other thermal models. For the duration from stem elongation to silking (SESI), calendar days were better estimators than the thermal models. From emergence to silking (ESI), the thermal models using air temperature were generally better estimators of ESI duration than calendar days.Key words: Maize, thermal indices

Gibberellins and sorghum development

Sorghum (Sorghum bicolor (L.) Moench) hybrids adapted for grain (cv. Northrup King X8102) or forage production (cv. Pride PF70) were grown in field trials at Lethbridge, Alta., Canada, and shoot cylinders containing the apical meristems were harvested at various developmental stages for analyses of endogenous gibberellin-like (GA-like) substances. Extracts were purified and chromatographed on sequential SiO2 partition columns and C18 reversed-phase high-performance liquid chromatography, and GA-like substances were detected and quantified by the cv. Tan-ginbozu dwarf rice microdroop assay. Concentrations of GA-like substances in the shoots were higher during vegetative growth than during shoot elongation or panicle elongation and the pattern of declining concentration of GA-like substances was observed for both hybrids over both field seasons. The qualitative distribution of GA-like substances was generally similar across hybrids and developmental stages, with a GA19-like substance accounting for about 60% of the total GA-like activity (GA19 is a native GA of sorghum). The exogenous application of GA3 promoted height growth and inhibited tillering, with maximal effects occurring when application was early, during rapid vegetative growth. Applications of GA3 subsequent to panicle initiation promoted panicle elongation but did not alter the time of anthesis. These results on endogenous GA concentration and response to exogenous GA3 application suggest a role for endogenous GAs in the control of shoot growth and development in sorghum.

Nitrogen fertilizer management of ratooned grain sorghum

Abstract Sorghum [Sorghum bicolor (L.) Moench] grown in a ratoon cropping system is an alternative double‐cropping scheme for the southeastern U.S. Visual symptoms of nitrogen (N) deficiency in the early growth of the ratooned crop suggested that improved N fertilizer management might increase grain yields of the ratooned crop. Five hybrids: Coker 7737, Gold Kist 802G, Northrup King NK 2660, DeKalb DK‐59 and Pioneer Brand 8311 were grown in a ratoon cropping system on a Greenville sandy clay loam (Rhodic Paleudult). Nitrogen fertilizer treatments for the ratoon crop were applied at flowering of the planted crop (90 kg ha‐1), immediately following ratooning (90 kg ha‐1) or split between flowering of the planted crop (45 kg ha‐1) and ratooning (45 kg ha‐1 ). The N concentrations in the grain and stover of the planted crop were increased by both N rates applied at flowering of the planted crop. Grain yields of the planted or ratooned crops were not affected by the timing of N fertilizer application for the r...

Registration of ‘Commandor’ Alfalfa

Crop ScienceVolume 27, Issue 6 cropsci1987.0011183X002700060045x p. 1305-1305 Registration of Crop Cultivars Registration of ‘Commandor’ Alfalfa C. C. Fox, C. C. Fox Scientist Northrup King Co., Stanton, MN, 55081Search for more papers by this authorW. J. Knipe, W. J. Knipe director of forage research Northrup King Co., Stanton, MN, 55081Search for more papers by this author C. C. Fox, C. C. Fox Scientist Northrup King Co., Stanton, MN, 55081Search for more papers by this authorW. J. Knipe, W. J. Knipe director of forage research Northrup King Co., Stanton, MN, 55081Search for more papers by this author First published: 01 November 1987 https://doi.org/10.2135/cropsci1987.0011183X002700060045xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume27, Issue6November–December 1987Pages 1305-1305 RelatedInformation