Late Bloom Stage Research Articles

Evaluation of chlorophyll fluorescence as a tool for the identification of drought tolerance in upland cotton

Chlorophyll fluorescence (CF) is one tool used by researchers to quantify plant water status during periods of limited water availability. The research reported herein was designed to evaluate a CF-based protocol as a tool for use in cotton, Gossypium spp. breeding programs for the identification of drought tolerant genotypes. Twenty genotypes were selected to represent diverse and distinct US germplasm pools. Replicated tests were performed in Lubbock and College Station, TX in 2006 and 2007. Dryland and irrigated treatments, as main plots, were applied in a randomized complete block design, split to genotypes. CF measurements were taken at mid-bloom and late bloom growth stages. Source leaf tissue was harvested at predawn and subjected to high temperature incubation with CF measurements subsequently taken hourly for 5 h. Drought stressed plants had not mobilized their carbohydrate reserves from their source leaves overnight and thus maintained cell viability and therefore higher CF values throughout the incubation and measurement period with the opposite being true for non-stressed plants. Fiber lint yield and fiber properties were measured for comparison with the CF data. Genotype × treatment effects complicated the classification of genotypic response to drought. Few and inconsistent correlations were found among CF values and lint yield or fiber properties. Data suggested that this procedure provides little potential in selecting plants for drought tolerance when plants are grown under field culture.

Bacterial abundance, biomass and production during spring blooms in the northern Barents Sea

Abstract To evaluate importance of bacterioplankton in the Barents Sea, we investigated the spatial and temporal distribution of bacterial abundance, biomass and production in relation to spring-bloom stages. During three cruises in 2003–2005, 12 stations were investigated. Average bacterial abundance (±S.D.) in the photic zone was 3.6±3.0×105 cells ml−1, corresponding to 7.1±6.1 mg C m−3. Bacterial production in the photic zone was measured using dual labelling technique with 3H-thymidine and 14C-leucine, resulting in average production rates (±S.D.) of 1.5±1.0 and 6.9±4.8 mg C m−3 d−1, respectively. In spite of low water temperature, the bacterial community was well developed and active. Similarity analysis of stations resulted in four distinct spring-bloom stages, covering pre- early-, late- and post-bloom stages. In the photic zone, bacterial biomass on average corresponded to 6±2% of phytoplankton biomass. Highest integrated bacterial biomass was observed at mid- to late-bloom stages. Average bacterial production equalled 32±6% (±S.E., n=24) of particulate primary production. The bacterial production to primary production ratio tended to increase at late-bloom stages. The observed bacterial activity illustrates the importance of the bacterial pathway for channelling carbon from DOC through the microbial food web back into the classical food web, which previously has not been adequately considered in plankton ecosystem models of the Barents Sea.

Water deficit effects on root distribution of soybean, field pea and chickpea

Cropping diversity in the central Great Plains of the United States could be increased by including suitable legumes in crop rotations. Water is limiting to all crops grown in this region and agronomic crops frequently experience water deficit stress during their life cycle. The ability of a plant to change its root distribution to exploit deeper stored soil water may be an important mechanism to avoid drought stress. An experiment was conducted to examine legume root system response to water deficit stress. Chickpea ( Cicer arietinum L.), field pea ( Pisum sativum L.), and soybean ( Glycine max L. Merr.) were grown at two water regimes: under natural rainfall conditions and irrigated to minimize water deficit stress. Root distributions for each species were measured at 0.23 m depth intervals to a depth of 1.12 m directly beneath the plants at the late bloom and mid pod fill growth stages. Roots were washed free of soil and were separated from soil debris by hand. Root surface area measurements were made and root weights were recorded for each depth interval. Water deficit did not affect the relative soybean root distribution. Approximately 97% of the total soybean roots were in the surface 0.23 m at both sampling times and under both water regimes. In contrast, water deficit stress resulted in a greater proportion of chickpea and field pea roots to grow deeper in the soil. Under irrigated conditions, about 80% of the chickpea and field pea roots were in the surface 0.23 m. Under dry conditions, about 66% of the total chickpea and field pea roots were in the surface 0.23 m and the remainder of the roots was deeper in the soil profile. Field pea had a root surface area to weight ratio (AWR) of 35–40 m 2 kg −1, chickpea had a AWR of 40–80 m 2 kg −1, whereas soybean had a AWR of 3–7 m 2 kg −1, depending on plant growth stage. The greater AWR indicates a finer root system for the field pea and chickpea compared with soybean. From a rooting perspective, chickpea may be the best suited of these species for dryland crop production in semi-arid climates due to an adaptive root distribution based on water availability and large root surface area per unit root weight.

Energy and protein utilization by goats fed Italian ryegrass silage treated with molasses, urea, cellulase or cellulase + lactic acid bacteria

The effects of different additives on ensiling of Italian ryegrass (IRG) silage and the resulting silages energy and nitrogen utilization and on methane (CH 4) emission by Japanese native goats were evaluated. The silages were prepared from IRG harvested at late-bloom stage. Different treatments, 13.3% molasses, 4.0% urea, 0.02% cellulase and 0.02% cellulase + 0.02% lactic acid bacteria (LAB) were mixed with IRG prior to ensiling, and compared to a control with no preservative. Diets consisted of corn and soybean meal with one of the silages. Goats were allocated to examine one of the treated diets in two metabolism trials. Each trial period lasted 21 days, with a 7-day period of adjustment, followed by a 7-day preliminary period and a 7-day period of total collection of digestion and metabolism data. Methane emission was measured in open circuit respiration chambers over three consecutive days for each goat. Urea treated IRG had a higher ( P<0.05) volatile ammonia nitrogen (NH 3-N/TN, 57%) compared to other silages. All treated silages had higher ( P<0.05) OM digestibilities except the cellulase treated silage. The cellulase + LAB treated silage diet had the lowest CH 4 kg −1 digestible organic matter intake (DOMI). Goats consumed similar N in all diets except the urea treated silage diet. All treated silage diets produced higher ( P<0.01) urinary N than that of the control diet. The CP digestibilities were similar ( P>0.05) in all treated silage diets except the molasses treated silage diet, where CP digestibility was the lowest. Urea treated silage diet produced a higher digestible N, but had a negative retained N due to a higher ( P<0.001) urinary N. Ensiling IRG with the additives led to higher digestible nutrient availability, but mixing urea resulted in increased N losses through feed, feces and urine. This study showed that IRG harvested at late-bloom stage could be ensiled without any additive, but mixing molasses, cellulase and cellulase + LAB prior to ensiling increased the proportion of ME to DE and could reduce the CH 4 emission rate per unit of DOM and retained energy (RE). Mixing urea increased the digestible OM and N intake, but increased the N excretion. Cellulase addition resulted in a decreased CH 4 production rate. However, IRG treated with molasses could increase retained energy and N besides reducing CH 4 and volatile N.

Feasibility of Grazing Sainfoin on the Southern Great Plains

Forage is often in short supply on southern Great Plains grasslands during spring because warm-season grasses are dormant or just beginning to grow. Sainfoin (Onobrychis viciifolia Scop.), a non-bloat-inducing legume, can provide forage in semiarid regions during spring when irrigated. A study was conducted to investigate yield, quality, and persistence of sainfoin in a subhumid region of the southern Great Plains without irrigation. Sainfoin was established in 1989 and grazed with steers at early or late bloom growth stages in 1990 and 1991 to remove 50 or 75% of the forage height. Forage yield averaged 2,480 and 4,110 kg ha-1, respectively in 1990 and 1991. Fifty to 80% of sainfoin's forage yield occurred prior to average stocking dates on warm-season pastures for summer grazing. Crude protein concentration averaged 15 and 19% and in vitro digestible dry matter averaged 57 and 62% in 1990 and 1991, respectively. Sainfoin survival was unaffected by grazing treatment through July 1991. After a severe drought from late July through August 1991, sainfoin stands were reduced 22% across treatments (P > 0.05). Sainfoin has potential to complement warm-season pastures in the southern Great Plains, but additional effort is needed to improve plant persistence.

Ensiling forage sorghum at two stages of maturity with the addition of lactic acid bacterial inoculants

Whole crop forage sorghum cultivar FS2 was harvested at the late bloom (20.7% dry matter (DM)) and soft dough (28.9% DM) stages of maturity. The sorghum was chopped to approximately 10 mm pieces and ensiled under laboratory conditions in 1.51 Weck glass jars. At ensiling, it was treated with two commercial silage inoculants: H/M F and Sil-All. The inoculants were applied at 10 6 colony-forming units g −1 DM. Silage with no additives served as a control. Three jars per treatment were opened on Days 1, 2, 5, 10 and 31 post-ensiling to study fermentation dynamics. After 31 days of ensiling the silages were analysed and subjected to an aerobic stability test lasting 5 days. The yield of the sorghum harvested at the late bloom and the soft dough stages was 11.8 ton DM ha −1 and 16.4 ton DM ha −1, respectively. The in vitro organic matter digestibility was 61.4% and 67.6%, respectively. At both stages of maturity the inoculants caused a more rapid rate of pH decline and a higher amount of lactic acid production. All the silages were well preserved. Silages of the sorghum ensiled at the late bloom stage with all treatments were stable after 5 days of aerobic exposure, whereas sorghum ensiled at the soft dough stage with the addition of the inoculants deteriorated upon aerobic exposure. This was evident from a significantly ( P<0.05) higher production of CO 2 as compared with the control, and increase in pH. It is concluded that addition of lactic acid bacterial inoculants to mature sorghum at ensiling might impair the aerobic stability of the silage.

Nitrogen Release from Crimson Clover in Relation to Plant Growth Stage and Composition

AbstractIncreased N‐use efficency and economic savings may result from a better understanding of N release patterns from legume residues. A 2‐yr field experiment was conducted on a Cecil fine sandy loam (clayey, kaolintic, thermic Typic Kanhapludult) to examine the effects of crimsom clover (Trifolium incarnatum L.) growth stage on dry matter accumulation, N concentration, and chemical composition in relation to N release under no‐tillage management. Crimson clover was harvested in the spring at four growth stages (late vegetative, early bloom, late bloom, and early seed set). Air‐dried plant material in 1‐mm mesh nylon bags was placed on the soil surface; retreived at 1−, 2−, 4−, 8−, and 16‐wk intervals; and analyzed for total N, C, cellulose, hemicellulose, and lignin concentrations. Averaged over 2 yr, dry matter production increased from 2.3 to 5.6 Mg ha−1, and N concentration declined from 30.2 to 21.2 g kg−1 as crimson clover matured from late vegetative to early seed set growth stages. Cellulose concentration increased by 66%, hemicellulose by 37%, and lignin by 87% from late vegetative to early seed set. Estimated clover N release at the 8‐wk retrieval was 28, 40, 40, and 54 kg ha−1 in 1989 and 51, 67, 73, and 55 kg ha−1 in 1990 for the late vegetative, early bloom, late bloom, and early seed set growth stages, respectively. Results indicated that allowing crimson clover to attain the late bloom stage prior to desiccation and planting of the summer crop can maximize clover top‐growth N content and subsequent N release.

Witchweed Management by Sorghum‐Sudangrass Seed Size and Stage of Harvest

AbstractCareful cultural management of field crops has become imperative in countries where chemical measures are not economically feasible. The occurrence of the endemic parasitic witchweed [Striga hermonthica (Del.) Benth] in production fields of sorghum‐sundangrass hybrid [Sorghum bicolor (L.) Moench ✕ S. sudanense Stapf. cv. Piper], Pioneer brand hybrid 988 (coded P988), is one example that requires such procedures. Study objectives were to relate: (i) P988 seed size (large and small) to witchweed germination, P988 root and shoot length, and weight and (ii) P988 seed size and harvest growth stage to P988 greenchop yield and sucrose content at three initial and subsequent P988 harvests at boot stage, late bloom stage, and maturity in witchweed‐infested fields. Seedlings of P988 grown from small seed had significantly shorter shoots but longer roots compared to those from large seed. Witchweed germination was not signficiantly affected by seed size of P988 but was postively correlated to P988 root length and root dry weight. Seed size of P988 had no significant effect on forage greenchop yield and forage sucrose of P988 at all harvests. Delaying initial harvest of P988 increased witchweed shoot dry weight with time and equated total yields, but reduced the quality of greenchop at late bloom and maturity. Delaying second and third harvests of P988 to maturity significantly increased greenchop yield of P988. Forage sucrose at maturity stage of second and third harvests exceeded forage sucrose at maturity of first harvest by 106 and 60%, respectively. Witchweed shoot dry weight was positively correlated with forage sucrose of P988. Growing small seeded P988 reduced witchweed incidence and sustained P988 yields when combined with harvesting at the boot stage on first harvest and at maturity of later harvests on witchweed‐infested soils.

Predation on eggs and larvae ofHeliothis virescens [Lep.: Noctuidae] by an adult predator complex in cage studies on cotton

Predation by a predator complex consisting of adults of the lygaeidGeocoris punctipes (Say), the nabidsNabis roseipennis Reuter and/orTropiconabis capsiformis Germar and the coccinelids,Hippodamia convergens Guerin-Meneville andColeomegilla maculata (DeGeer) onHeliothis virescens (F.) eggs, 1st-instar larvae or both on late pinhead square and early bloom stage cotton was evaluated in field cages in Mississippi. Prey densities of 4 (11, 512/ha) or 8 per cage and predator: prey (P:p) ratios of 1∶1, 2∶1, 3∶1, 4∶1 and 5∶1 were used. Prey were labeled with phosphorus-32 or carbon-14 to determine predator ingestion and effectiveness. Average percent egg predation as a function of P:p ratio ranged from 2.1 to 12.1 for a 48 h period. The average percent predation on larvae as a function of P:p ratio ranged from 5.3 to 22.0. The hemiptera fed more than the coleoptera on larvae, andG. punctipes was the best egg predator. For the range of predator densities used, the average area of discovery for the predator complex was 6.98 × 10−3 m/day and 2.34 × 10−2 m/day when exposed to eggs and larvae, respectively.

EFFECTS OF STAGE OF MATURITY OF TIMOTHY HAY AND CONCENTRATE SUPPLEMENTATION ON PERFORMANCE OF LACTATING DAIRY COWS

The effects of concentrate supplementation of timothy hay cut at the late-boot and early-bloom was tested with dairy cows during two feeding and two digestibility trials. The diets for each trial contained the following hay to concentrate ratios: 100:0, 85:15, 70:30 and 55:45. Daily dry matter intake and fat-corrected milk production, respectively, were 15.1, 16.8, 18.6, 19.4 kg; 16.7, 20.7, 23.1, 21.0 kg for the four diets containing early-cut timothy hay and 11.0, 14.7, 17.2, 19.8 kg; 8.4, 10.7, 13.3 and 15.9 kg for the late-cut timothy hay. Percent digestibilities of the four diets containing early-cut and late-cut timothy hay, respectively, were 65.6, 65.6, 66.9, 66.8 and 53.6, 53.6, 60.2, 62.9 for dry matter; 62.5, 63.7, 65.2, 65.3 and 24.0, 39.3, 53.3, 60.0 for nitrogen; 70.3, 70.3, 68.4, 67.8 and 53.7, 53.4, 60.1, 62.6 for gross energy; 66.4, 65.3, 67.1, 66.6 and 55.0, 54.5, 61.4, 63.5 for cell wall constituents; 68.2, 65.8, 64.9, 63.4 and 50.8, 48.2, 52.7, 52.1 for acid detergent fiber. Timothy hay cut at late-boot stage as sole source of feed supported a daily milk production of 16.7 kg compared to 15.9 kg for cows consuming timothy hay cut at late-bloom stage supplemented with 9 kg of concentrate.

Inheritance of Leaflet Size and Specific Leaf Weight in Alfalfa1

The combining abilities for leaflet size and specific leaf weight (SLW) were determined at two different stages of growth in a 7 ✕ 7 diallel cross population of alfalfa (Medicago sativa L.). Both characters were heritable since the general combining ability was larger than either the specific combining ability or the reciprocal effects. Greater genetic variance was observed at an early bud stage than at a late bloom stage. Large differences in SLW were obtained only at an early bud stage. Leaflet size and SLW were not correlated. Genotypes that combined larger leaflet size and higher SLW were identified. Thus both traits would respond to selection in a plant breeding program. The correlation of these characters with forage yield was generally poor.

CONTRIBUTION OF STEMS AND LEAVES TO THE YIELD AND NUTRIENT LEVEL OF IRRIGATED ALFALFA AT DIFFERENT STAGES OF DEVELOPMENT

In Roamer alfalfa (Medicago media Pers.) the nutritive value in leaves deteriorated much more slowly than that in stems. The percentage of N declined 29% in leaves and 49% in stems; percentage P declined 4% in leaves and 34% in stems, and percentage digestible energy declined 3% in leaves and 34% in stems between early leaf and late bloom growth stages. The total yield of nutrient increased rapidly to the early bloom stage, but quite slowly thereafter. Because of possible leaf loss, delayed harvesting of an alfalfa crop beyond the mid-bloom stage would not be warranted to gain yield even when only one cutting is taken.

Lipid Deposition on Leaves of Canada Thistle Ecotypes

The amount of lipid present on leaves of Canada thistle (Cirsium arvense(L.) Scop.) varied due to ecotype, site where grown, and date of sampling. Thistles from a site with the greatest wind movement and greatest evaporation produced the most lipid per unit area of leaf. The relative lipid yield of ecotypes was similar at different locations. Deposition of lipid on the leaves of Canada thistle increased from the early bud stage to the first bloom and late bloom stages of growth. The amount of lipid on the leaves and previous data on the response of these ecotypes to (2,4-dichlorophenoxy) acetic acid (2,4-D) were highly correlated. Three ecotypes with the most lipid were most resistant and four ecotypes with the least lipid were most susceptible to 2,4-D spray. Two ecotypes were inconsistent in that comparison.

CONTRIBUTION AND NUTRITIVE VALUE OF THE MAJOR PLANT COMPONENTS OF OATS THROUGH PROGRESSIVE STAGES OF DEVELOPMENT

Two oat (Avena sativa L.) cultivars, Harmon and Sioux, and an unlicensed cultivar of Avena orientalis L., referred to as "Yorkton," were harvested at the early leaf, before boot, boot, headed, early bloom, late bloom, milk, dough, and ripe stages. Yorkton gave smaller yields than the other two cultivars at all stages after heading, but was slightly more leafy. Percent leaves by weight for all cultivars varied from near 90% in first cut to about 14% when ripe. Crude protein of leaves declined from 30 to 6% over the nine cuttings whereas that of stems went from 24 to 5%. Leaf lignin increased from 35 to 50% through the whole range of growth whereas stem lignin increased more rapidly from 45 to 70% in a shorter period of time. Leaves had 20% more energy than did stems. They were also 10% more digestible as determined by in vitro digestible organic matter. As whole plant feed there was no advantage in delaying harvest beyond the milk to soft dough stage.

Berry Response of ‘Thompson Seedless’ and ‘Perlette’ Grapes to Application of Gibberellic Acid1

Abstract At a stage just after bloom, gibberellin (GA3) at 600 ppm induced maximum increase in berry size of ‘Thompson Seedless’ grapes. Seven days after fruit-set, only 25 ppm were required for maximum response. In both instances, regression lines of best fit between GA3 concentration and berry weight indicated a logarithmic response. At both late bloom and early fruit-set stages there was a large increase in berry size, but at a time halfway between these stages the response to GA3 was much less striking. After fruit-set there was a gradual decrease in response to GA3. Increase in berry size due to girdling, on both vines sprayed at bloom and fruit set with GA3 and on unsprayed vines was maximum when berry diameter was 3-10 mm at time of girdling. There was no interaction between berry response to girdling and to gibberellin application. At fruit-set, ‘Perlette’ berries generally responded to increases in GA3 concentration up to 600 ppm.

Magnesium‐Phosphorus Interrelationships in Tomatoes

AbstractTomato (Lycopersicon esculentum) plants were grown in nutrient solution with Mg levels which varied from 0.96 ppm to 96 ppm and with P levels of 5 and 31 ppm. At low levels of Mg better growth was obtained when the P level was low. At high levels of Mg better growth was obtained when the P level was high. A nutrient solution containing 96 ppm of Mg promoted plant growth when the P concentration was 31 ppm but reduced growth when the P concentration was 5 ppm. Phosphorus fertilization of tomatoes grown on clay soils reduced the Mg content of the leaves from 1.2 to 0.65%. Analysis of leaves of commercial tomato fields during the late bloom stage showed a negative relationship between Mg and P (r = —0.896).