Search Results

You are looking at 31 - 40 of 1,660 items for :

  • optimization x
  • Refine by Access: User-accessible Content x
Clear All
Free access

Esther Giraldo, Margarita Lopez-Corrales, and Jose Ignacio Hormaza

germplasm bank from collections in Aragon (northern Spain). The results obtained in this work indicate that SSRs are excellent codominant markers to optimize fig germplasm management, allowing distinction of synonyms and homonyms and studies of conserved

Free access

Inmaculada Moreno-Alías, Hava F. Rapoport, Rafael López, Lorenzo León, and Raúl de la Rosa

percentage of plants with a short juvenile period and testing the applicability of the early selection criterion for juvenile period ( De la Rosa et al., 2006 ) to different seedling ages. In particular, we attempt to define more precisely and optimize the

Full access

Catherine S. Fleming, Mark S. Reiter, Joshua H. Freeman, and Rory Maguire

enough water applied to treatments 0.0 × ET and Tens-60 to optimize yields ( Table 2 ), and therefore, residual NO 3 -N was greater in those treatments. In Fall 2010, significant differences between treatments were observed to 20 inches. As seen in Spring

Free access

Kyoung-Shim Cho, Hyun-Ju Kim, Sang-Mi Moon, Hyun-Gu Choi, and Young-Sang Lee

Traditionally fatty acid composition used to be analysed by GC and the sample preparation consisted of lipid extraction from sample and subsequent methyl esters preparation, which are time-consuming and cumbersome. As an alternative, simultaneous extraction/methylation methods are being developed for rapid and simplified sample preparation. To optimize one-step extraction/methylation method for analysis of fatty acid composition in brown rice and adlay seeds, various factors, such as sample to reaction solution ratio, reaction time and temperature, and shaking intensity, were altered and resultant fatty acid composition data were evaluated in comparison with previous reports. The ratio of sample weight to reaction solution volume was the most critical factor in that higher sample to reaction solution ratio caused overestimation of palmitic acid and linoleic acid composition, resulting in underestimation of oleic acid. Lower reaction temperature also induced overestimation of linoleic acid and underestimation of oleic acid. Reaction duration and the intensity of shaking prior to and during the reaction, however, induced no significant changes in analysis results. In conclusion, the optimum condition for brown rice was mixing 5 grains (about 0.2 g) of brown rice with 680 μL of methylating mixture and 400 μL of heptane, followed by reaction at 80 °C for 2 hours.

Open access

Scott B. Lukas, Joseph DeFrank, Orville C. Baldos, and Ruijun Qin

Seed dormancy is an evolutionary adaptation for increasing seedling survival by delaying germination and is found in many families of seed plants. Although dormancy is ecologically important, it becomes problematic during agronomic production and restoration. Torrid panicgrass (Panicum torridum) is a native Hawaiian annual grass that has been identified as a re-vegetation candidate for seasonally dry areas. Torrid panicgrass seed appears to possess a nondeep to intermediate physiological dormancy. This research aimed to characterize dormancy relief parameters by 1) evaluating exogenous hormonal, reactive oxygen intermediates, and simulated combustion product treatments; and 2) determining optimized storage conditions of relative humidity (RH) and temperature over a 10-month duration. Results indicate that all exogenous chemical treatments tested were not effective at relieving the dormancy present in torrid panicgrass. Optimal storage conditions to relieve dormancy were found with seeds equilibrated to 12% RH, stored at 30 °C for a period of 8 months resulting in 55% germination. Maintenance of viability for long-term storage up to 10 months was best achieved with seeds stored at 12% RH at 10, 20, or 30 °C.

Free access

Hein J. Gerber, Willem J. Steyn, and Karen I. Theron

The European fig cultivars Bourjasotte Noire, Col de Damme Noire, and Noire de Caromb were recently introduced to the Western Cape Province of South Africa. Producers struggle to implement effective commercial practices that will optimize yield of quality fruit. A phenological study was conducted to establish the optimum 1-year-old shoot length to maximize yield. The number of fruit, budbreak, and shoot growth on 1-year-old shoots comprising four length categories (‘Bourjasotte Noire’: 10 to 15, 25 to 40, 50 to 65, and 75+ cm; ‘Col de Damme Noire’ and ‘Noire de Caromb’: 10 to 20, 30 to 50, 60 to 80, and 100+ cm) were evaluated. In ‘Bourjasotte Noire’, all four categories seem to be suited for reproduction in the current season and also provide sufficient new shoot growth to ensure a fair yield the next season. In ‘Col de Damme Noire’, category four seems to be the best 1-year-old shoot length for reproduction both in terms of fruit number and fruit size. However, yield on these shoots may not be optimal the next season, because current-season shoots are too short. It seems that this cultivar will require pruning to stimulate strong new shoot growth that will ensure regular, high yields. In ‘Noire de Caromb’, category one shoots are very productive relative to their length. Categories two and three were also relatively productive, whereas category four was less productive but developed a large number of current-season shoots similar in length to category one that should be productive the next season. These results will allow us to develop pruning strategies to ensure an optimal balance between current-season yield and the development of new fruiting wood to ensure regular, high yields. It also suggests that the three cultivars studied will require differential application of horticultural practices to attain regular, high yields of large fruit.

Open access

Qiang Zhang, Minji Li, Beibei Zhou, Junke Zhang, and Qinping Wei

meteorological factors and the quality of ‘Fuji’ fruits in the two dominant production regions in China are discussed in depth to provide a theoretical basis for apple regional plantation optimization and cultivation technique adjustments based on climate

Free access

Roland E. Roberts and Michael G. Hickey

Texas processing potato growers want high tuber yield and soluble solids with optimal nitrogen (N) fertilization to avoid leaching N into underground water. A 3-year on-farm study demonstrated petiole and soil testing methods for N enabling growers to apply N at rates and times for maximum yield with acceptable specific gravity. For example, a FL-1553 crop received 160 N kg/ha in irrigation water spread over 126-day season. Sampling every 2 weeks from early vegetative stage to harvest showed petiole N of 22,000 ppm on day 40; 6,000 ppm on day 54; 3,000 ppm on day 68; 7,000 ppm on day 96; and 2,000 ppm by day 110. At harvest total tuber N = 1.12%; tuber specific gravity = 1.081 (17.1 % FritoLay solids); and processor acceptable yield = 304 q/ha. The crop removed nearly all applied N.

Free access

Athanasios P. Papadopoulos

The greenhouse cover has previously been shown to have large effects upon the greenhouse environment, crop productivity and energy use. However, in most cases, because of inadequate treatment replication, the extent of these effects has been impossible to quantify with confidence. In the fall of 1987, a new greenhouse complex of 9 mini greenhouses (6.4m × 7.2m, each) was constructed at the Harrow Research Station on the principles of the 3×3 Latin Square experimental design and with glass, double polyethylene film and double acrylic panel greenhouse covers as the three levels of treatment in the Latin Square. During the spring seasons of 1988 and 1990 the greenhouse cucumber cultivar Corona was cropped in rockwool in all 9 mini greenhouses, under 3 day air (DAT: 18°C, 21 °C and 24°C) and 3 night air temperatures (NAT: 16°C, 18°C and 20°C), superimposed across the rows and columns of greenhouses, respectively, to estimate yield and energy use response to DAT, NAT and greenhouse cover variation. Early marketable yield was highest at the 18/18 and 18/20°C DAT/NAT combinations and final marketable yield was highest at 18°C DAT regardless of NAT. Yield differences due to the greenhouse cover were insignificant. However, there were consistent differences in greenhouse air RH due to greenhouse cover (60%, 70% and 75% daily averages for glass, double polyethylene and double acrylic, respectively). Also, there were significant energy savings with the use of double polyethylene or double acrylic, as compared to glass greenhouse cover, and with low DAT and NAT (28%, 15% and 12% energy use reduction, respectively).

Free access

Alex B. Daniels, David M. Barnard, Phillip L. Chapman, and William L. Bauerle

The primary goal of this study was to determine the optimum number of substrate moisture sensors needed to accurately determine substrate water content for 10 tree species in a containerized nursery. We examined variation in volumetric water content (VWC, m3·m−3) within containers, within species, among species, and over time. Across time, differences among species were not significant (P = 0.14). However, differences among time periods and the interaction effect between species and time periods were significant (P < 0.001). Seasonal differences in within-species variation were also evident in nine of the 10 species. In an attempt to understand species-specific mechanistic factors that influence within-species variation in VWC, we accounted for physiological and morphological differences affecting transpiration with a spatially explicit mechanistic model, MAESTRA. Neither estimated transpiration rate per whole crown or m2 of leaf area could explain variation in VWC. Based on our results, we recommend species-specific sensor deployment and report sensor quantities that estimate the mean substrate VWC of each species within a confidence interval of ± 5% VWC. Given the economic value of water and its control on biomass production, we conclude that nursery managers can maintain optimal substrate moisture with minimal sensor deployment.