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1.
The Mexican rice borer, Eoreuma loftini (Dyar), is the key pest of sugarcane, Saccharum hybrids, in south Texas, having largely displaced the sugarcane borer, Diatraea saccharalis (F.), and it is moving into rice- and sugarcane-growing areas of east Texas and Louisiana. While a number of alternative weed and crop hosts have been reported, the extent to which they might support Mexican rice borer populations is unknown. This study involved choice assays that compared oviposition preference for and larval infestations of five mature graminaceous weed species. Levels of infestation between sugarcane and corn, Zea mays L., crop hosts and between corn and sorghum, Sorghum bicolor (L.) Moench, were also assessed. We determined that the average number of larval entry holes in sudangrass stems was ≥2.5-fold more than for any of the other four weed host plants, that corn had ≥5.9-fold more larval entry holes than sorghum and ≥8.2-fold more than sugarcane. Greater oviposition and infestation of one non-crop host over another was not related to numbers of stems per plant, but was associated with the greater stem diameter and abundance of dry leaf tissue found in Sudangrass, Sorghum bicolor (L.) Moench ssp. drummondi (Nees ex Steud.) de Wet & Harlan, johnsongrass, S. halepense (L.) and barnyardgrass, Echinochloa crus-galli (L.) P. Beauv.; relative to the other weed species in this study. In terms of the crop plants, stalk diameter and quantity of dry leaf tissue were not associated with numbers of eggs or larval entry holes in the choice assays between corn and sorghum, and between sugarcane and corn. While corn has been known as a host of the Mexican rice borer for at least 84 yr, its role in area-wide population dynamics and control efforts has likely been greatly underestimated.  相似文献   

2.
The oviposition preference of Chilo sacchariphagus (Bojer) (Lepidoptera, Crambidae) to Erianthus arundinaceus (Retz.) Jeswiet (Poaceae) was tested against sugarcane (Saccharum spp. hybrids) to assess whether effective control of the pest can be achieved in the field by using perimeter trap cropping with this plant species. Results from large cage and greenhouse experiments showed that E. arundinaceus clone 28NG7 acted as a dead-end trap plant, attracting oviposition by C. sacchariphagus females and hosting young larvae in terminal green leaves, but reducing by 4.8- to 7.5-fold the survival rate of larvae in stalk. Two field trials demonstrated the efficiency of trap cropping with E. arundinaceus, with a 2 to 9-fold reduction in number of bored internodes per stalk and a 22% mean increase in cane yield. In a third field trial, reduction of injury was observed up to 40 m from the E. arundinaceus border. We conclude that trap cropping with E. arundinaceus may reduce C. sacchariphagus damage in sugarcane crop. Further trials are needed to confirm these results in commercial fields.  相似文献   

3.
The Mexican rice borer, Eoreuma loftini (Dyar), attacks crops including corn, Zea mays L., rice, Oryza sativa L., sorghum, Sorghum bicolor (L.) Moench, and sugarcane, Saccharum spp. Strongly resistant varieties of any kind, native or otherwise, have not been identified. A field plot corn variety test using two transgenic Bt varieties, Pioneer 31G71, expressing the Cry1F insecticidal protein, and Golden Acres 28V81, expressing the Cry1A.105, Cry2Ab2, and Cry3Bb1 insecticidal proteins, and two non-Bt controls, Dekalb DKC 69-72 and BH Genetics 9050, all four commonly grown in the Lower Rio Grande Valley of Texas, showed that, although oviposition preference was not affected, 28V81 resisted larval stalk boring to the extent that Mexican rice borer injury was almost non-existent. Pioneer 31G71 was infested nearly as much as the controls, but larval development to adulthood was reduced by ≈70%. Rearing larvae on 5, 50, 500, and 5000 μg of corn leaf tissue per ml of artificial diet showed that, while the three lowest concentrations did not affect larval growth and development, the high concentration of 28V81 reduced survivorship to the pupal stage, decreased weight of 4-wk-old larvae, and prolonged development to pupation. Lower numbers of pheromone trap-captured adults at the edges of commercial Bt and non-Bt corn fields showed that populations were lower at the Bt cornfields, suggesting a lesser rate of adult production. Because corn is a preferred host plant over sugarcane, sorghum or rice, use of resistant transgenic Bt corn varieties will likely protect the crop from the substantial injury that can be caused by the pest. This study also suggests that Bt genes might result in similarly strong resistance when inserted in other vulnerable crops such as sugarcane.  相似文献   

4.
On-farm field experiments were conducted in 2004 and 2007 to assess the suitability of novaluron, a chitin synthesis inhibitor, for sugarcane borer, Diatraea saccharalis (F.), management in Louisiana sugarcane (Saccharum spp. hybrids). Aerial insecticide applications reproducing commercial production practices were made when D. saccharalis infestation levels exceeded a recommended action threshold. In addition to decreased D. saccharalis infestations, 6.3 – 14.5-fold reductions in end of season injury, expressed as the percentage of bored sugarcane internodes, were observed in plots treated with novaluron. D. saccharalis control in novaluron plots was equivalent to (P > 0.05) or better (P < 0.05) than that achieved with tebufenozide, an ecdysone agonist that has been extensively used for over a decade on sugarcane. With a numerical trend of a 3.1-fold decrease in percent bored internodes, the pyrethroid gamma-cyhalothrin seemed less effective than the biorational insecticides in protecting sugarcane against D. saccharalis. Using continuous pitfall trap sampling, no measurable (P > 0.05) decreases in predaceous and non-predaceous soil-dwelling non-target arthropods were associated with insecticides. However, numerical trends for decreases in immature crickets associated with novaluron and gamma-cyhalothrin were recorded in 2007. Our data suggest that novaluron will fit well in Louisiana sugarcane integrated pest management.  相似文献   

5.
Harvesting products from plants for conversion into renewable resources is increasing in importance. Determination of nutrition requirements for the applicable crops is necessary, especially in regions where the biofuel feedstock crops have not been historically grown. Sunflower (Helianthus annuus L.), two hybrids and one variety; sweet and grain (milo) sorghums (both Sorghum bicolor L.), one variety each, and sweet corn (Zea mays var. rugosa Bonaf.), four cultivars, were provided the recommended and twice the recommended rate of fertilizer. Biomass, expressed liquid volumes and sugar contents of sweet sorghum and sweet corn were determined. Grain yields of milo and sunflower and oil content of sunflower were determined. Sweet corn stalk sugar levels were below what is expected from field corn (maize), and were not affected by fertilizer rate. Sweet sorghum biomass and sugar content were within expected ranges and not affected by fertilizer rate. Milo grain yields were higher with increased fertilizer. Seed yield in Sunflower, which was below expected levels, was inconsistently affected by fertilizer rate, years or varieties. Overall crops year and cultivar/variety had more effect on results than did fertilizer. There does not appear to be a reason to provide fertilizer above recommended rates in production of these crops.  相似文献   

6.
Sorghum (Sorghum bicolor (L.) Moench) is a starch-rich grain similar to maize (Zea mays L.), but sorghum has been underutilized for biobased products and bioenergy. This study was designed to investigate the effects of supercritical-fluid-extrusion (SCFX) of sorghum on ethanol production. Morphology, chemical composition, and thermal properties of extruded sorghum were characterized. Analysis of extruded sorghum showed increased measurable starch content, free sugar content, and high levels of gelatinized starch. SCFX cooked and non-extruded sorghum were further liquefied, saccharified, and fermented to ethanol by using Saccharomyces cervisiae. The ethanol yield increased as sorghum concentration increased from 20 to 40% for both extruded and non-extruded sorghum. Ethanol yields from SCFX cooked sorghum were significantly greater than that from non-extruded sorghum (>5%).  相似文献   

7.
The bioconversion into ethanol of insect (Sitophilus zeamais), mold (Aspergillus flavus) and sprout-damaged maize and sorghum was investigated. Kernel test weight losses due to insect damage in maize were almost twice compared to sorghum (18.6 vs. 10.7%). All damaged kernels lost some of the starch and increased soluble sugars, ash and crude fiber. The mold-damaged sorghum contained approximately five times more FAN compared to the control. The sprout-damaged kernels contained the highest amounts of reducing sugars prior (11 g/L) to and at the end (146.5 g/L) of liquefaction with α-amylase. Ethanol yields based on the already damaged grain indicated that sprout-damaged kernels yielded similar amounts compared to sound kernels (381.1 vs. 382.6 L/ton and 376.6 vs. 374.8 L/ton of sorghum or maize respectively). The insect-damaged maize and sorghum have reduced ethanol yields compared with the controls (29 and 23% respectively), and this negative result was mainly due to dry matter losses during the inadequate storage. Despite differences in ethanol yield, all treatments have similar conversion efficiencies (76.1–89.9%) indicating the robustness of yeast facing biotic-damaged feedstocks. This research demonstrates that the use of already damaged insect, mold or sprouted kernels is feasible and a good alternative for biorefineries.  相似文献   

8.
《Field Crops Research》2003,82(1):59-73
Stalk water content is an important variable for a sugarcane simulation model as sugar industries in many countries use cane yield and sucrose content on a wet mass basis for payment and yield reports. The prime objective was to develop a stalk water content module (SWCM) that can be incorporated into a sugarcane simulation model. SWCM starts from consideration of the dynamics of water concentration (ρ, g water g−1 dry matter) along stalks and through seasons. The quantities of stalk water were modelled separately for the top and basal sections of the millable stalks. Field observations showed that the stalk water concentration (ρ) declined from 7.8 to 11.8 in the top internodes to 1.6–2.9 g water g−1 dry matter in bottom internodes. In the basal section, ρ ranged from 1.98 in winter to 2.83 g water g−1 stalk dry matter in summer. A two-parameter equation was used to model ρ and resulted in a range of coefficients of determination from 0.8 to 0.97 for six varieties. The SWCM was developed to simulate both the effects of seasonal variation and the age of internodes on the quantity of stalk water. The module was incorporated into a process oriented model of sugarcane growth for validation against field observations in tropical and subtropical areas of Australia and Hawaii, USA. Comparison of observed yields with cane yield simulated by the model that included the SWCM, gave an average of R2 of 0.95, compared with the average of R2 of 0.97 for simulation of stalk dry matter. The average relative root mean squared error (RMSE) was 15.2% in simulation of cane yield and 15.1% for simulation of cane dry weight. The module can be readily incorporated into a model that simulates sugarcane dry matter so that commercial crop yield can be estimated.  相似文献   

9.
《Field Crops Research》1999,64(3):273-286
On-farm research to evaluate the productivity and nitrogen (N) nutrition of a rice (Oryza sativa L.)–wheat (Triticum aestivum L.) cropping system was conducted with 21 farmers in the piedmont of Nepal and with 21 farmers in northwest Bangladesh. In Nepal, two levels of N-fertilizer (0–22–42 and 100–22–42 kg N–P–K ha−1) and farmers’ nutrient management practices were tested in the rice season, and three levels of N (0–22–42, 70–22–42, and 100–22–42) and farmers’ practices were evaluated in the wheat season. The treatments in Bangladesh included a researchers managed minus-N plot (0–22–42) and the farmers’ practices. Rice and wheat yields were higher in all treatments than the 0–22–42 control plots, with the exception of rice with the farmers’ practices at one location in Bangladesh. The researchers’ treatment of 100–22–42 in Nepal resulted in larger yields of both rice and wheat than the farmers’ practices, indicating that farmers’ rates of N-fertilizer (mean 49 kg N ha−1) were too low. Delaying wheat seeding reduced yields in the fertilized plots in both countries, especially as N-fertilizer dose increased. Soil N-supplying capacities (SNSC), measured as total N accumulation from the zero-N plots (0–22–42), and grain yields without N additions were greater for rice than for wheat in both Nepal and Bangladesh. Higher SNSC in rice was probably due to greater mineralization of soil organic N in the warm, moist conditions of the monsoon season than in the cooler, drier wheat season. However, SNSC was not correlated with total soil N, two soil N availability tests (hot KCl-extractable NH4+ or 7-day anaerobic incubation), exchangeable NH4+ or NO3−. Wheat in Nepal had greater N-recovery efficiency, agronomic efficiency of N, and physiological efficiency of N than rice. Nitrogen internal-use efficiency of rice for all treatments in both countries was within published ranges of maximum sufficiency and maximum dilution. In wheat, the relationship between grain yield and N accumulation was linear indicating that mobilization of plant N to the grain was less affected by biotic and abiotic stresses than in rice.  相似文献   

10.
The development of aryloxyphenoxypropionate (APP)-resistant grain sorghum could provide additional opportunities for postemergence herbicide grass control in grain sorghum. Field experiments were conducted in Texas (Bushland, and Yoakum), Kansas (Dodge City, Garden City, Hays, Manhattan, Colby, Ottawa, and Tribune), and South Dakota (Highmore) to evaluate the efficacy of quizalofop tank mixes in APP-resistant grain sorghum. Quizalofop was applied alone or in combination with dicamba, 2,4-D, prosulfuron, 2,4-D + metsulfuron methyl, or halosulfuron methyl + dicamba. Herbicides were applied when sorghum was 12–50 cm in height. Overall weed control was greater when quizalofop was applied with other herbicides than when applied alone. At 2 and 4 weeks after treatment (WAT), large crabgrass [Digitaria sanguinalis (L.) Scop.], giant foxtail (Setaria faberi Herrm.), and green foxtail [Setaria viridis (L.) Beauv.] control were greater than 90% when quizalofop was applied alone or in combination with dicamba, halosulfuron methyl + dicamba, or prosulfuron. Palmer amaranth (Amaranthus palmeri S. Wats.), puncturevine (Tribulus terrestris L.), and tumble pigweed (Amaranthus albus L.) control were greater than 90% in all treatments except when quizalofop was applied alone. Herbicide treatments, except those that included 2,4-D, caused slight to no sorghum injury. Grain sorghum yield was greater for all herbicide treatments compared to the weedy check. This research showed that application of quizalofop in combination with broadleaf weed herbicides provided excellent weed control in sorghum.  相似文献   

11.
《Field Crops Research》2005,93(1):94-107
Bangladesh is currently self sufficient in rice (Oryza sativa L.), which accounts for approximately 80% of the total cropped area, and 70% of the cost of crop production. However, farmers are increasingly concerned about the perceived decline in productivity, expressed as the return on fertiliser inputs. Agronomic efficiency is a measure of the increase in grain yield achieved per unit of fertiliser input that can provide a way to quantify the observation of farmers. This study indicates that the yields achieved where only P and K fertiliser were applied ranged from 3–5 t ha−1, indicating good soil fertility, particular in terms of soil N supply (37–112 kg N ha−1). However, at recommended rates and at rates used by farmers, the yield response to application of fertiliser N was low. Data shows that grain yields were significantly correlated in both years (R2 = 0.77 and R2 = 0.67) with plant uptake in nitrogen. The internal nitrogen use efficiency seems to confirm that sink formation was limited by factors other than nitrogen. Low agronomic efficiency (5–19 kg grain kg−1 N) was caused by poor internal efficiency (45–73 kg grain kg−1 N), rather than low supply of soil N or loss of fertiliser N. Thus, often the applications of large amounts of N fertiliser (39–175 kg N ha−1) by farmers to increase yields of high yielding variety Boro rice were not justified agronomically and ecologically. A rate of 39 kg N ha−1 is very low, hardly an environmental threat. No one single factor could be identified to explain the low internal efficiency. Therefore, it is concluded that the data presented tend to confirm the indication that yields are limited by a factor other than nitrogen, which could be crop establishment, plant density, water or pest management, micro-nutrients deficiency, poor seed and transplanted seedling quality, varieties and low radiation.  相似文献   

12.
Direct-seeded rice systems are increasing in Asia as farmers respond to the high labor cost and shortage of water. Echinochloa crus-galli is one of the most problematic and competitive weeds in direct-seeded rice systems. Because of concerns about excessive herbicide use, there is an interest in developing cultural weed management strategies. However, the design of such strategies requires a better understanding of the weed response to crop density, nutrition, and water regime. A study was therefore conducted in pots to determine the effect of water (flooded and aerobic), nitrogen (N) fertilization (0, 100, and 200 kg N ha−1), and rice density [0, 4 rice plants (≈20 kg seed ha−1), and 16 rice plants (≈80 kg seed ha−1)] on the growth and reproduction of E. crus-galli. When grown alone, the growth and seed production of E. crus-galli were higher in flooded conditions than in aerobic conditions. However, no such differences were observed when E. crus-galli was grown with rice interference. E. crus-galli growth and seed production increased with increases in N rate. Irrespective of water regime and N rate, the growth and seed production of E. crus-galli declined with increases in rice density. At 100 kg N ha−1, for example, E. crus-galli shoot biomass and seed production decreased by 84–86% and 82–87%, respectively, when grown with 16 rice plants compared with its growth without rice interference. The results suggest that growth and seed production of E. crus-galli can be greatly reduced by increasing rice seeding rate. However, there is a need to involve other weed management strategies to achieve complete control of E. crus-galli and other weed species.  相似文献   

13.
The sugarcane borer, Diatraea saccharalis (F.) (Lepidoptera: Crambidae), is the key insect pest of sugarcane, Saccharum spp., grown in Louisiana. For more than 40 years, Louisiana sugarcane farmers have used a value of 10% internodes bored at harvest as the economic injury level (EIL). Three plant-cane studies were conducted to re-evaluate the long-standing sugarcane borer EIL level using the most recently released varieties of sugarcane. Varieties were exposed to artificially enhanced borer infestations; the experimental treatments consisted of borer control with insecticides or no control. Data were collected on infestation intensity, damage intensity, and associated yield losses. Crop yields from plots were obtained by mechanical harvesting, and losses were classified as field losses, e.g. losses of gross tonnage in the field and factory losses, e.g., losses that were realized at the factory as cane is being milled. Farm income is based on the product of these two measures of yield, i.e. cane yield×sugar yield. In our study, seasonal stalk-infestation counts did not reveal any indication of preference by the borer moths for a specific variety; infestation pressure was generally uniform within a season among the varieties that we planted. Significant differences were detected among the varieties for harvest percentage of internodes bored as well as yields between borer-controlled and non-controlled plots (P<0.05). In general, varieties were less susceptible to losses in the field (sugarcane yields) than in the factory (sugar yields). As a group, the most recent varieties released to Louisiana growers exhibit more tolerance to the borer than varieties grown 40 years ago. The percent reduction in sugar/ha loss per 1% internodes bored has decreased from an average of 0.74 for varieties grown in the 1960s to 0.61 as a mean for the newly released varieties. Although the cost associated with an insecticide application for sugarcane borer control has increased nearly 4-fold from 1971 to present, sugar yields have increased by approximately 60% allowing farmers to offset some of these increased costs. Our economic analysis indicates that the EIL of 10% internodes bored is too high, considering the high yielding potential and susceptibility of currently grown varieties. For the most at risk farmer, the tenant farmer, a more appropriate value for the EIL is 6% internodes bored. However, this EIL can be raised 12% if a resistant variety is grown.  相似文献   

14.
A series of experiments was set up to examine the effects of nitrogen on rice (Oryza sativa L.) resistance against Nilaparvata lugens (Stål) and Sogatella furcifera (Horváth). Egg laying by N. lugens was reduced on the indica variety IR60. Nymph biomass (N. lugens and S. furcifera) was also lower on IR60: this was associated with low honeydew production and a high proportion of xylem-derived honeydew in N. lugens but not in S. furcifera. Nitrogen increased egg-laying by S. furcifera and increased N. lugens nymph biomass on all varieties tested. Oviposition and egg mortality in both planthopper species were examined on plants at 15, 30 and 45 days after sowing (DAS). Sogatella furcifera laid more eggs on plants at 15 DAS, but laid few eggs during darkness; N. lugens continued to lay eggs on older rice plants (30 DAS) and during darkness. Egg mortality was high on cv. Asiminori, highest at 45 DAS, and higher for S. furcifera than for N. lugens. Mortality of S. furcifera eggs was associated with lesions around the egg clusters. These were more common around clusters laid during the day and suggested induction by Asiminori of an ovicidal response. Egg mortality declined under higher soil nitrogen levels. Results are discussed in the light of improving rice resistance against planthoppers and reducing rates of planthopper adaptation to resistance genes.  相似文献   

15.
Because CO2 is needed for plant photosynthesis, the increase in atmospheric CO2 concentration ([CO2]) has the potential to enhance the growth and yield of rice (Oryza sativa L.), but little is known regarding the impact of elevated [CO2] on grain quality of rice, especially under different N availability. In order to investigate the interactive effects of [CO2] and N supply on rice quality, we conducted a free-air CO2 enrichment (FACE) experiment at Wuxi, Jiangsu, China, in 2001–2003. A long-duration rice japonica with large panicle (cv. Wuxiangging 14) was grown at ambient or elevated (ca. 200 μmol mol−1 above ambient) [CO2] under three levels of N: low (LN, 15 g N m2), medium (MN, 25 g N m2) and high N (HN, 35 g N m2 (2002, 2003)). The MN level was similar to that recommended to local farmers. FACE significant increased rough (+12.8%), brown (+13.2%) and milled rice yield (+10.7%), while markedly reducing head rice yield (−13.3%); FACE caused serious deterioration of processing suitability (milled rice percentage −2.0%; head rice percentage −23.5%) and appearance quality (chalky grain percentage +16.9%; chalkiness degree +28.3%) drastically; the nutritive value of grains was also negatively influenced by FACE due to a reduction in protein (−6.0%) and Cu content (−20.0%) in milled rice. By contrast, FACE resulted in better eating/cooking quality (amylose content −3.8%; peak viscosity +4.5%, breakdown +2.9%, setback −27.5%). These changes in grain quality revealed that hardness of grain decreased with elevated [CO2] while cohesiveness and resilience increased when cooked. Overall, N supply had significant influence on rice yield with maximum value occurring at MN, whereas grain quality was less responsive to the N supply, showing trends of better appearance and eating/cooking quality for LN or MN-crops as compared with HN-crops. For most cases, no [CO2] × N interaction was detected for yield and quality parameters. These data suggested that the current recommended rates of N fertilization for rice production should not be modified under projected future [CO2] levels, at least for the similar conditions of this experiment.  相似文献   

16.
Since 2005, the evolution and spread of herbicide-resistant Echinochloa crus-galli biotypes have posed a serious threat to crop production in the Philippines. A comprehensive knowledge of E. crus-galli ecology and fecundity is fundamental in managing different biotypes of this weed. It was hypothesized that (a) high weed plant density produces more biomass and fertile seeds per unit area, (b) rice interference reduces the biomass and fecundity of the weed, and (c) a delay in weed emergence reduces the soil seed bank. In 2013, experiments were conducted in the wet season (WS) and dry season (DS), to understand the effect of E. crus-galli densities (40 and 80 plants m−2) on its growth, survival, and fecundity, with varying emergence times of 2, 15, 30, and 45 d after rice emergence (DARE). Relative to the weed plants grown without rice interference, E. crus-galli growth and seed production was lower in the presence of rice. Percent survival and plant height of E. crus-galli declined in a linear manner in the DS, and declined in a quadratic manner in the WS. Tiller number, inflorescence number, inflorescence biomass, and shoot biomass per plant declined in an exponential manner, with a delay in emergence of each cohort relative to rice. Across rice seeding rate, weed density, and emergence time, there was a linear relationship (y = 110x − 272 in the DS and y = 100x − 220 in the WS) between E. crus-galli shoot biomass and the number of seeds plant−1. Relative to the late-emerging weed cohorts, E. crus-galli seed production (1320–1579 seeds plant−1), 1000-seed weight (2.2–2.9 g), and seed yield (2808–2334 kg ha−1) were higher when seedlings emerged with the crop (2 DARE). None of the seedlings that emerged 45 DARE produced viable seeds. Seed germination of the first two cohorts (2 and 15 DARE) ranged from 84 to 91%. The delay in emergence of E. crus-galli beyond 30 DARE reduced the percentage of germinable and viable seeds, and increased the percentage of non-viable seeds produced plant−1. The results suggest that cultural weed management approaches that delay the emergence of E. crus-galli can reduce weed biomass and seed production, and is thus valuable for preventing seed rain to the seed bank by noxious weed biotypes in the field.  相似文献   

17.
Comparable data are lacking from the range of environments found in sub-Saharan West Africa to draw more general conclusions about the relative merits of locally available rockphosphate (RockP) in alleviating phosphorus (P) constraints to crop growth. To fill this gap, a multi-factorial field experiment was conducted over 4 years at eight locations in Niger, Burkina Faso and Togo. These ranged in annual rainfall from 510 to 1300 mm. Crops grown were pearl millet (Pennisetum glaucum L.), sorghum (Sorghum bicolor (L.) Moench) and maize (Zea mays L.) either continuously or in rotation with cowpea (Vigna unguiculata Walp.) and groundnut (Arachis hypogaea L.). Crops were subjected to six P fertiliser treatments comprising RockP and soluble P at different rates and combined with 0 and 60 kg N ha−1. For legumes, time trend analyses showed P-induced total dry matter (TDM) increases between 28 and 72% only with groundnut. Similarly, rotation-induced raises in cereal TDM compared to cereal monoculture were only observed with groundnut. For cereals, at the same rate of application, RockP was comparable to single superphosphate (SSP) only at two millet sites with topsoil pH-KCl<4.2 and annual average rainfall>600 mm. Across the eight sites NPK placement at 0.4 g P per hill raised average cereal yields between 26 and 220%. This was confirmed in 119 on-farm trials revealing P placement as a promising strategy to overcome P deficiency as the regionally most growth limiting nutrient constraint to cereals.  相似文献   

18.
A small-scale mashing (SSM) procedure requiring only 300 mg of samples was investigated as a possible method of predicting ethanol yield of sorghum grain. The initial SSM procedure, which was conducted similarly to the mashing step in a traditional fermentation test, hydrolyzed just 38.5–47.2% of total sorghum starch to glucose. The initial procedure was simplified to contain only one liquefaction step, which did not influence subsequent saccharification. Thereafter, parameters such as temperature, pH, enzyme dosage, and saccharification time were optimized. Results showed that 91.2–97.5% of the total starch in 18 sorghum hybrids had been hydrolyzed to glucose using the following conditions: liquefaction at 86 °C for 90 min, 20 μL of α-amylase per 30 g of sample; pH adjustment by adding 50 μL of 2 M acetate buffer at pH 4.2 to each microtube; saccharification at 68 °C for 90 min, 200 μL of amyloglucosidase per 30 g of sample. There were strong linear correlations between completely hydrolyzed starch (CHS) from SSM and ethanol yields from both traditional (R2 = 0.86) and simultaneous saccharification and fermentation (SSF, R2 = 0.93) procedures. CHS was a better indicator for predicting ethanol yield in fermentation than total starch.  相似文献   

19.
《Field Crops Research》2004,88(1):57-67
Increasing atmospheric CO2 concentration has led to concerns about global changes to the environment. One area of global change that has not been fully addressed is the effect of elevated atmospheric CO2 on agriculture production inputs. Elevated CO2 concentration alterations of plant growth and C:N ratios may modify C and N cycling in soil and N fertility. This study was conducted to examine the effects of legume, soybean (Glycine max (L.) Merr.), and non-legume, grain sorghum (Sorghum bicolor (L.) Moench.) carbon dioxide-enriched agro-ecosystems on N soil fertility in a Blanton loamy sand (loamy siliceous, thermic, Grossarenic Paleudults). The study was a split-plot design replicated three times with crop species (soybean and grain sorghum) as the main plots and CO2 concentration (ambient and twice ambient) as subplots using open top field chambers. Fertilizer application was made with 15N-depleted NH4NO3 to act as a fertilizer tracer. Elevated CO2 increased total biomass production in all 3 years of both grain sorghum (average 30%) and soybean (average 40%). With soybean, while no impact on the plant C:N ratio was observed, the total N content was greatly increased (average 29%) due to increased atmospheric N2 fixation with elevated CO2 concentration. With grain sorghum, the total N uptake was not affected, but the C:N ratio was markedly increased (average 31%) by elevated CO2. No impact of elevated CO2 level was observed for fertilizer N in grain sorghum. The results from this study indicated that while elevated CO2 may enhance crop production and change N status in plant tissue, changes to soil N fertilizer application practices may not be needed.  相似文献   

20.
Reduced lignin concentration in brown mid-rib mutants in both maize and sorghum have resulted in improved dry matter digestibility, increased milk yield and higher energy in lactating cows. However, the mutations were not widely deployed due to concern that reduced lignin concentration might increase vulnerability to lodging and stalk rot incidence. The objective of this study was to determine the effects of the mutations on stalk strength and stalk rot resistance in both sorghum and maize. Six brown midrib (bmr) sorghum, four brown midrib (bm) maize, and their normal isolines were evaluated for stalk strength and stalk rot disease reaction at two locations in four replications. Three randomly selected plants in each plot were inoculated with Macrophomina phaseolina at 14 d after flowering by using the toothpick inoculation technique. On 28 d after inoculation, the plants were rated for disease severity by measuring the length of necrotic lesions in the stalks. Stalk strength was determined from another three random plants in each plot by using a rind penetrometer. The mutations had no effect on stalk rot disease severity in either sorghum or maize though stalks strength was markedly affected by the mutations in both species. While maize bm entries broke easily in response to mild mechanical stress, bmr sorghums did not exhibit sign of stalk collapse in all backgrounds. The result suggests that the bmr genes in both maize and sorghum can be deployed without incurring losses to stalk rot disease.  相似文献   

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