| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
| ||||||||||||||||||||||||||||||||||||||||
Understanding canola (Brassica napus L.) yield plasticity under weed-free dryland conditions is essential for greater adoption of canola in nontraditional semiarid regions. A field study (Angadi et al., 1358–1366) conducted for 3 yr indicated that canola compensated seed yield across a range of uniform and nonuniform populations. Pods per plant, determined by branching and pod determination retention, was the most important yield component for yield compensation. Weather conditions played a major role in yield adjustment.
Near-Infrared Spectroscopy on Chopper
As improving maize (Zea mays L.) forage yield and quality is a major goal for corn breeders in northern Europe, Welle et al. (1407–1413) coupled near-infrared spectroscopy (NIRS) with harvesting to eliminate time-consuming sample preparation and laboratory analyses. Calibrations developed in 1999 using a spectrometer mounted on a chopper were validated with 159 samples from the 2000 harvest resulting in standard errors of prediction of 12.5 g kg-1 for dry matter (DM), 22.1 g kg-1 for starch, 19.8 g kg-1 for in vitro digestibility, and 16.7 g kg-1 for soluble sugars. The results indicate that NIRS on chopper can determine DM accurately, rank hybrids for starch plus sugars, and group for in vitro digestibility. Dry matter NIRS determinations were more precise than the reference method. Instrument standardization could be achieved through spectral matching and database updating. The dramatic increase in the number of plots analyzed expedites development of new maize forage products.
Breeding Cassava for the Underprivileged
An international cassava (Manihot esculenta Crantz) breeding program was established in the early 1970s to help less privileged sectors of the tropical populations. After spending the initial decade for germplasm collection and basic breeding, the later decades were devoted to applied breeding in collaboration with national programs. Fresh root yield of populations was improved by >100% and root dry matter content by >20%. The target population of small farmers captured a large proportion of the economic benefits. The understanding of crop germplasm being a common heritage and the determination of agricultural scientists to use this for the welfare of neediest people were the social factors for the overall success. See Kawano (1325–1335).
Quantifying Freezing Resistance in Rose Clover
There is a need for rose clover (Trifolium hirtum All.) with improved winter growth, extended seasonal forage production, and improved winter survival to increase the usefulness of this legume as a reseeding forage crop. Nunes and Smith (1349–1357) conducted a study to: (i) develop screening methods to measure freezing resistance; and (ii) discriminate freezing stress resistance differences in selected germplasm, both in controlled and field conditions. An electrolyte leakage test performed on young leaves at -14°C test temperature for 60 min proved to be the most efficient for detecting both acclimation and cultivar differences in rose clover freezing tolerance. The ranking of freezing stress resistance of acclimated rose clover was ‘Overton R18’ > ‘Hykon’ = ‘Kondinin’. The experimental lines TX- B97 and TX-B29 had the apparent ability to respond rapidly to cold field conditions by reversing the deacclimation process. Other clover entries changed their rate of deacclimation in response to cold temperature but not as rapidly as TX-B97 and TX-B29.
Stockpiled Annual Ryegrass for Winter Forage
Livestock operations in the lower Midwest are interested in stockpiling annual ryegrass (Lolium multiflorum Lam.) as a source of high-quality winter forage. Kallenbach et al. (1414–1419) determined the yield and forage quality of stockpiled annual ryegrass compared with cereal rye during two winters in Missouri. Stockpiled annual ryegrass yields ranged from 825 to 2356 kg ha-1. Forage quality tended to decline during winter, but neutral detergent fiber never exceeded 455 g kg-1. These results show that livestock producers could use stockpiled annual ryegrass as a source of high-quality winter forage in the lower Midwest.
Evaluation of Spring Wheat for Production of Cantonese Asian Noodles
Cantonese noodles are seen as an alternative or a complement to the traditional pan bread market for producers of hard spring wheat (Triticum aestivum L.). Identification of traits, effects of regional environment, and suitable genotypes necessary to produce desirable quality traits such as minimal discoloration for Cantonese noodles is desired. Davies and Berzonsky (1313–1319) examined wheat quality characteristics related to noodle discoloration in nine spring wheat genotypes grown in eight North Dakota environments. Cantonese noodle sheets were made and discoloration measurements taken. Genotype and environment interactions were significant for wheat quality characteristics. Genotypes exhibiting low kernel PPO activity, moderate protein content, bright kernels, and low ash content had superior noodle color after 24 h. Notwithstanding the inherent difficulties with producing Cantonese noodles from hard spring wheats, the authors conclude that the development of acceptable genotypes with noodle quality is possible. Additionally, the development of a dual-purpose spring wheat is achievable by simultaneously selecting for noodle quality and traits having a neutral effect on traditional spring wheat end products.
Autumn Defoliation Effects on Alfalfa
Untimely autumn harvesting may increase alfalfa (Medicago sativa L.) winter injury, but the physiological basis for this response is not understood. Haagenson et al. (1340–1348) observed that defoliation in mid-October significantly increased winter injury and decreased spring vigor in West-Central Indiana. Roots of defoliated plants had decreased starch and protein accumulation, but increased sugar concentrations in December. Defoliation did not reduce expression of several cold hardiness genes associated with genetic variation in winter hardiness. Although positively associated with genetic differences in winter hardiness, factors other than root sugar accumulation and expression of these cold acclimation-responsive genes regulate defoliation-induced changes in winter survival of these alfalfa cultivars.
Root Physiology of Winter Hardy Alfalfa
It is not clear why extensive shoot growth in autumn results in poor alfalfa (Medicago sativa L.) winter survival. Haagenson et al. (1441–1447) measured biochemical and physiological characteristics in roots of several germplasms selected for high winter hardiness and less fall dormancy. High sugar, amino N, and protein concentrations in roots in December were positively associated with decreased winter injury of experimental germplasms selected for decreased fall dormancy. These traits may be useful in further enhancing alfalfa winter hardiness while simultaneously decreasing fall dormancy.
Improving Shaded Turf Performance
Steinke and Stier (1399–1406) compared the responses of Kentucky bluegrass (Poa pratensis L.), supina bluegrass (Poa supina Schrad.), and creeping bentgrass (Agrostis stolonifera L.) to liquid vs. granular N and three levels of trinexapac-ethyl growth regulator under 80% shade. Supina bluegrass provided the best turf at 1.27 cm mowing height followed by creeping bentgrass. Creeping bentgrass responded best to liquid N (foliar uptake) and Kentucky bluegrass responded best to granular N (root uptake). Supina bluegrass response to N type was seasonally dependent. Monthly and bimonthly applications of trinexapac-ethyl improved turf quality but the effect of bimonthly applications dissipated within 6 wk after application.
Soybean Seed Composition and Transcript Abundance
Thomas et al. (1548–1557) quantified effects of anticipated global climate change on soybean seed composition. This study used two levels of carbon dioxide and temperatures from 28/18 up to 40/30°C in 4°C increments. The effects of supraoptimal temperature on oil, protein, and carbohydrate composition of soybean seeds were carefully defined. Changes in seed composition due to elevated temperature were pronounced, and there was no effect of a doubled CO2. Supra-optimal temperatures affected genetic transcripts in seeds, but there were no CO2 effects.
Cotton Leaf Blade Total Nitorgen Concentration
Assessing the nitrogen (N) status of cotton by means of the total N concentration of leaf blades could be useful, but a rigorous examination of this diagnostic tool has not been done. Bell et al. (1367–1374) calibrated the tissue test to identify easily N deficient and N sufficient cotton. Nitrogen rate field experiments were conducted at 12 sites in Louisiana, Arkansas, Mississippi, and Alabama. Results indicated that yield losses would be expected at early bloom if leaf N was <4.3% and at mid-bloom, <4.1%. Earlier published studies found lower critical values we found and the use of earlier values may result in N-deficient cotton and decreased yields.
Smooth Bromegrass Genetic Diversity
The level of genetic diversity within and among smooth bromegrass (Bromus inermis Leyss.) cultivars and land races is unknown. Diaby and Casler (1538–1547) quantified diversity within and among 40 smooth bromegrass cultivars and land races using 97 random amplified polymorphic DNA markers. Markers were associated with geographic origin, climatype, phenotypic classification, and selection for in vitro dry matter digestibility. Clustering based on molecular markers was broadly concordant with clustering based on agronomic and morphological traits. As with other cross-pollinated species, most genetic variability was within populations. There has been no loss of genetic diversity in the 50 yr since smooth bromegrass breeding began in North America.
| ||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
