首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 78 毫秒
1.
The genetic diversity in forty-nine Agave tequilana Weber var. Azul accessions from different regions of the Appellation of Origin Tequila, and eighteen Agave angustifolia Haw. var. Lineño accessions from the south of the state of Jalisco, were evaluated using morphological traits and RAPD (Randomly Amplified Polymorphic DNA) markers. Thirteen morphological characters and three different random 10-mer primers were used. Statistical analysis for these traits revealed that all of them were statistically different (α = 0.05). Three principal components (PC) accounted for 79.9% of the total variability. The number of teeth found in 10 cm, the distance between the last lateral and the apical spine, tooth length, tooth basal width, maximum distance between teeth and leaf width were the most important traits. Besides the wide morphological variation found in both varieties, we were able to separate A. angustifolia from A. tequilana in two main groups using the dendrogram (r = 0.82) and plot from the PCA analysis. The RAPD analysis generated 46 clear and reproducible fragments, 24 of them (52%) were polymorphic, and this polymorphism was higher in A. tequilana (35%) than in A. angustifolia (24%). The dendrogram that was based on RAPD data, revealed two main groups similar to the morphological analysis with some discrepancies. Despite the low correlation found between morphological and molecular data (r = 0.31), these analyses were able to separate the agave varieties used in this study and were informative and complementary.  相似文献   

2.
There are 32 species of Flourensia genus with 9 native to Mexico. These species contain compounds with potential use for pest control. In this paper, we report the antifungal activities of ethanol extracts from three endemic species in Coahuila state: Flourensia microphylla, Flourensia cernua, and Flourensia retinophylla. Also, preliminary information on the chemical composition of the extracts is included. Antifungal activity was tested against three pathogens attacking commercial crops: Alternaria sp., Rhizoctonia solani, and Fusarium oxysporum. The extracts concentration varied from 10 to 1500 μl l−1. The ANOVA showed highly significant differences (P ≤ 0.01) with the extracts, the doses, and on the interaction extract × dose. Inhibition effect was observed from 10 μl l−1 in all three species. Total inhibition was found only with F. cernua and F. retinophylla at 1000 μl l−1 for R. solani, the three species inhibited the three pathogens at 1500 μl l−1. Infrared analysis showed similar absorption signals for the extracts of the three species although in different concentration. This suggests that similar compounds may be present. The control of these pathogens by natural compounds is interesting both for environmental and economic reasons. The use of semiarid lands plants may improve the socioeconomic level of the people within the region.  相似文献   

3.
The genetic control determining the days to flowering, defined as the number of days from emergence to the beginning of flowering is considered an important characteristic for breeding purpose. We investigated this factor in kenaf (Hibiscus cannabinus L.), as part of an agroindustrial project in northwest Argentina. A diallelic cross approach was considered in this study. Six highly inbred photosensitive cultivars were used in the cross, namely, Endora, Pandora, Tainung 1, Line 42, Line 21, and Line 29. Significant differences among F1 family means as well as among general combining ability (GCA) and specific combining ability (SCA) components were found based on the Griffing genetic-statistical method IV, Model 1. A predominant additive effect was detected for the days to flowering, giving high heritability estimates (H = DGD = 0.96; h2 = 0.69), and suggests the possibility of effective selection for earliness in these cultivars. Early flowering in Line 29 was highly heritable, and therefore, is important for breeding purposes. Line 42, despite being the earliest, did not transmit this characteristic to its progenies, possibly because of epistatic genetic effects. The regression of the covariances of F1 families on the non-recurrent parent (Wr) and the variance of the “n” families (Vr) revealed that some dominance effects also occurred in the form of a partial dominance for early flowering. These results support the evidences revealed by the analysis of means of combinations between early and late flowering lines.  相似文献   

4.
《Field Crops Research》1999,61(3):193-199
The prominent effects of a soil surface crust on crop production, impedance to seedling emergence and reduced infiltration rate, were examined using a quantitative land evaluation model under the Sahelian environmental and soil conditions of north-central Burkina Faso. The model integrated data from climate, soil and crop for quantifying potential grain yield of sorghum (Sorghum bicolor), grown on a sandy loam soil for 14 production years (1977–1990). Crust development was induced using `simulated rainfall' with an intensity of 75 mm h−1 from a 2 m height. Results revealed that seeding sorghum in small holes without sufficiently breaking the surface crust depressed grain yield. Observed and potential yield correlated closely over a 7-year period (r = 0.79, p < = 0.05). Substantial yield gap was found between estimated potential yield (crust broken scenario set to 75% of the predicted yield) and observed, indicating however, the possibility of significantly improving yield by using appropriate tillage to break the crust before seeding.  相似文献   

5.
《Field Crops Research》1999,61(1):23-35
Field experiments were conducted to investigate the performance of temperate legume species in rice-based cropping systems in a warm-temperate environment in Nepal. Over the period 1994–1996, various legume species were grown during the winter season (October–May) in the Kathmandu valley (27° N, 1350 m asl) with the aim of evaluating their biomass production and N fixation. A wide range of legume species including food, feed and green manure crops proved to be very well adapted to the winter growing conditions in this environment. The cultivation of temperate legume crops therefore, constitutes an alternative to traditional cropping practices such as growing wheat or leaving the land fallow. The temperate species appeared to capitalise on generally favourable growing conditions such as long growing season, low pest and disease pressure, high radiant energy receipt and cool night temperatures. However, performance varied greatly between species and years. Total dry matter yields ranged from 2 to 20 t ha−1 obtained with lentil (Lens culinaris Medic) and bitter lupin (Lupinus mutabilis), respectively. Highest seed yields were produced by fababean (Vicia faba) (5 t ha−1) and field pea (Pisum sativum var. arvense) (3 t ha−1) in the first season. Nitrogen yields and quantities of N fixed ranged from 18 to 481 kg ha−1 and from 0 to 463 kg ha−1, respectively. Large amounts of N were fixed by species such as fababean, Persian clover (Trifolium resupinatum) and bitter lupin. Early sowing in autumn was shown to be beneficial for some crops such as fababean, vetch (Vicia benghalensis) and Persian clover. In these cases, it is, therefore, important to reduce the turn-around interval after rice. Further research is required to fully determine the potential of temperate legume species in these environments with particular emphasis given to the identification of the most adapted cultivars and to reduce the need for irrigation of these winter crops.  相似文献   

6.
The perennial C4 grass Miscanthus has been proposed as a biomass energy crop in Europe. Effects of crop age, irrigation and nitrogen fertilization on biomass and energy yields and N content of Miscanthus were investigated and the energy costs of production determined. After an establishment period of 1 year, cultivation of Miscanthus resulted in a dry matter production of over 37 t ha−1 year−1 over a period of 4 years. Irrigation and nitrogen level greatly affected Miscanthus biomass yield. In absence of N fertilization, irrigation did not modify biomass yield and the effect of irrigation increased with the increase in N level. The average N response ranged from 37 to 50 kg biomass kg−1 N applied. Because the calorific value of Miscanthus biomass (16.5 MJ kg−1) was not affected by irrigation and N fertilization, energy production depended exclusively on biomass yield. Maximum energy yield was 564 GJ ha−1 year−1. Without N supply and irrigation, energy yield was 291 GJ h−1. Net energy yield, calculated as the difference between energy output and input, but without inclusion of drying costs, was 543 GJ ha−1 with N fertilization and irrigation and 284 GJ ha−1 without; the ratios of energy output to input in crop production were 22 and 47, respectively.  相似文献   

7.
The compositions of essential oils of 19 accessions belonging to six different Achillea species, transferred from the natural habitats in 10 provinces of Iran to the field conditions, were assessed. The relationship between the leaf areas of selected accessions with their essential oil content was also investigated. Essential oil yield of dried plants obtained by hydro-distillation ranged from 0.1 to 2.7% in leaves. Results indicated a significant variation in oil composition among and within species. Total of 94 compounds were identified in 19 accessions belonging to the six species of A. millefolium, A. filipendulina, A. tenuifolia, A. santolina, A. biebersteinii and A. eriophora. The major constituents of the leaves in the tested genotypes were determined as germacrene-D, bicyclogermacrene, camphor, borneol, 1,8-cineole, spathulenol and bornyl acetate. According to the major compounds, four chemotypes were defined as: (I) spathulenol (1.64–34.31%) + camphor (0.2–15.61%) (7 accessions); (II1) germacrene-D (18.78–23.93%) + borneol (7.93–8.26%) + bornyl acetate (11.56–14.66%) (5 accessions); (II2) germacrene-D (13.28–36.28%) + bicyclogermacrene (5.93–8.4%) + 1,8-cineole (15.26–19.41%) + camphor (14.95–23.32%) (2 accessions); (III) borneol + camphor (52.04–63.27) (2 accessions); (IV) germacrene-D (45.86–69.64%) (3 accessions). The relationships of chemotypes with soil type and climatic conditions of collected regions were assessed, as probable reasons of high variations in essential oil components, and discussed.  相似文献   

8.
《Field Crops Research》2006,98(1):52-59
This study explored whether the average grain weight of wheat tends to be reduced when grain number is increased due to either competition or, to a consistent increase in the relative proportion of grains of smaller weight potential. Three field experiments considering environmental, genetic and environmental × genetic effects on yield and its main components were analysed during the 2003/2004 growing season in two different locations within the Mediterranean area of Catalonia, Spain. The relationship between grain weight and number of grains per unit land area was analysed for both the average of all grains (AGW) and for grains in specific positions of the main-shoot spikes: proximal (CPg) and distal (CDg) grains of central spikelets, and proximal grains of the near apical (APg) and near basal (BPg) spikelets. The proportional contribution of grains per spike for the different grain positions and the relative contribution of spikes per m2 made by the main shoot or tillers were also examined.In the three experiments, AGW was reduced when grain number was increased due to genetic and/or environmental factors. However, the slopes of the straight-lines that represented the negative relationship between grain number and grain weight were lower (less negative) and less significant for CPg (b = −0.20, P > 0.20), CDg (b = 0.06, P > 0.20) and BPg (b = −0.21, P > 0.20) than for AGW (b = −0.40, P < 0.05). The proportional contribution of distal grains and tiller spikes (both with relatively light grains) were directly related to grain number increases. Therefore, as grain number increased there was a higher proportion of grains of low potential weight. Thus, the average grain weight was concomitantly reduced when grain number increased by increasing the proportion of “small grains” in the canopy independently of any competitive relationship between growing grains.  相似文献   

9.
《Field Crops Research》1999,63(2):99-112
Field experiments were conducted at Gatton and Dalby in southeastern Queensland to determine parameters associated with radiation interception and biomass and nitrogen (N) accumulation for the ley legume species, phasey bean (Macroptilum lathyroides (L.) Urban) and vigna, (Vigna trilobata (L.) Verdc.). Sesbania (Sesbania cannabina Retz.), a native legume species, and soybean (Glycine max (L.) Merrill)) were included in the study for comparison. The most important differences between species related to differences in radiation interception, radiation-use efficiency (RUE), N-accumulation efficiency and the partitioning of N to plant parts. During early growth, soybean intercepted more radiation than the other species, primarily because of its greater leaf area index (LAI). Sesbania had the highest RUE (1.08 g MJ−1) followed by phasey bean (0.94 g MJ−1), soybean (0.89 g MJ−1) and vigna (0.77 g MJ−1). The efficiency of N-accumulation was greater in soybean (0.028 g N g−1) and phasey bean (0.030 g N g−1) than in vigna (0.022 g N g−1) and sesbania (0.021 g N g−1). In all species, the proportion of N allocated to leaves declined throughout the experimental period, being more rapid in soybean than in sesbania and phasey bean. Despite this decline in total N partitioned to the leaves, both soybean and phasey bean maintained a relatively stable specific leaf nitrogen (SPLN) throughout the experimental periods although sesbania and vigna displayed rapid decreases in SPLN. The large variation between species in RUE and N-accumulation efficiency indicates that the development of ley legume cultivars with a combination of traits for more efficient legume production, water use and soil N-accumulation in the water-limited environments of the grain belt of eastern Australia may be possible. The sensitivity of forage production, water use and soil N-accumulation to variation in RUE and N-accumulation efficiency needs to be quantified using modeling techniques prior to embarking on screening programs to select appropriate germplasm for evaluation studies.  相似文献   

10.
《Field Crops Research》1999,63(1):19-34
Two modelling approaches were used to quantify photoperiod and temperature responses of time from emergence to visible flower buds in nine quinoa (Chenopodium quinoa Willd.) cultivars. The first, non-interactive model, considers temperature and photoperiod responses as independent, and the threshold photoperiod, critical photoperiod, and base temperatures as constants. The second, interactive model, considers these attributes as variable, and allows for interaction between photoperiod and temperature responses. Controlled-environment experiments with a factorial combination of temperature and photoperiod provided information on responses, and data from field experiments were utilized in tests of the predictive capacity of the models.The two models were very similar in their goodness of fit and predictive capacity, but testing revealed that some assumptions about the interactive model were not fulfilled, whereas the non-interactive model is more consistent with the data. Both the models failed to predict dates of visible flower buds when average temperatures during the phase were >20°C; it is proposed that interaction between irradiance receipt and high temperature in controlled environments result in lower optimum temperatures there than in the field. Differences between field data and predicted values were eliminated when predictions were recalculated assuming no optimum for the temperature response.All nine cultivars examined are short-day plants. A juvenile sub-phase was observed in the six cultivars for which it was tested; and its duration was negatively associated with the latitude of origin of the lines (R2 = 0.9, p < 0.05). Photoperiod sensitivity was negatively associated with the latitude of origin of the lines (R2 = 0.55, p < 0.05) and positively associated with duration of the basic vegetative phase (minimal time between emergence and visible flower buds) (R2 = 0.55, p < 0.05) using the non-interactive model. Photoperiod and temperature response parameters were not significantly associated with the latitude of origin for the interactive model (p > 0.05).  相似文献   

11.
The research of alternative crops for biomass production for energy indicates giant reed (Arundo donax L.), widespread spontaneous plant in Mediterranean regions, among the species at high aptitude for accumulation of biomass. Within the activity of an E.U. programme (CEE FAIR CT 97-2028 “Giant reed (A. donax L.) Network. Improvement, productivity and biomass quality”, germplasm of giant reed were collected to evaluate potential production and the phenotypic and genotypic variability, the heritability in order to selecting the best genotypes.In 1997 and 1998, trials were carried out in Primosole site (Piana of Catania, sea level, 37°25′N latitude; 15°30′E longitude), utilizing rhizomes of 39 clones collected in Sicily and Calabria. The rhizomes were transplanted in springtime. Phenological (date of flowering), biometrical (stem density, stem height, number of nodes per stem, diameter and thickness of stems, weight of fresh and dry biomass of leaves, stems and inflorescence) and productive (yield) data were measured. Harvest were carried out in February 1988 and 1989.Yield of 39 clones studied was, in the average, 10.6 t ha−1 of dry matter in the first year and 22.1 t ha−1 in the second one. The clone no. 4 (Piazza Armerina) and the clone no. 20 (Capo d’Orlando) maintained their high productive aptitude in both years; they yielded respectively, 13.1 and 14.1 t ha−1 in the first year and 34.2 and 26.9 t ha−1 in the second one.The yield results positively correlated to stem density, stem weight and plant height. Four characters: biomass yield, stem weight, stem density and stem height showed a significant variance among clones without significant interaction with year. Among the eleven characters measured only yield, stem weight, stem density and stem height had moderate heritability (h2), comprised between 23 and 48% showing promise for genetic improvement.  相似文献   

12.
Within the past decade, the desire for alternative sources of fuels, chemicals, and other industrial materials has received increased attention. Sunflower (Helianthus annuus L.) oil has the potential to be improved for nutritional and industrial purposes through selection and breeding. The narrow genetic base of cultivated sunflower has been broadened by the infusion of genes from wild species, resulting in a continuous improvement in agronomic traits. The genus Helianthus is comprised of 51 species and 19 subspecies with 14 annual and 37 perennial species. Interest in using wild species in breeding programs has increased, but concerns about the introduction of low oil concentration and quality from the wild species persist. Two annual desert species, Helianthus anomalus Blake and H. deserticola Heiser, are excellent candidates for increasing oil concentration and enhancing quality based on their adaptation to desert environments. The objective of this study was to collect achenes of H. anomalus and H. deserticola from the desert southwest USA and assess their potential for improving oil concentration and quality in cultivated sunflower. The sunflower collection took place from 16 to 23 September 2000 and covered a distance of 4100 km in three states: Utah, Arizona, and Nevada. The only H. deserticola population collected had an average oil concentration of 330 g/kg, whereas the two populations of H. anomalus had an oil concentration of 430 and 460 g/kg, the highest concentration recorded in any wild sunflower species. The linoleic fatty acid concentration in the oil of H. anomalus populations was uncharacteristically high for a desert environment, approaching 700 g/kg. A linoleic acid concentration of 540 g/kg in H. deserticola was more typical for a desert environment. H. anomalus has the largest achenes and the highest oil concentration of any wild sunflower species, and the same chromosome number (n = 17) as cultivated sunflower. These features will facilitate the introduction of genes from this wild annual progenitor into cultivated sunflower. The lower saturated fatty acid profile in this species is also a desirable trait offering the potential to reduce saturated fatty acids in cultivated sunflower. Further research will be needed to determine the inheritance of the fatty acids and oil concentration. Other agronomic traits will need to be maintained during the introgression of these traits into cultivated sunflower oil.  相似文献   

13.
《Field Crops Research》2006,96(1):142-150
The distribution, population density and incidence of plant parasitic nematodes and associated damage to yam (Dioscorea spp.) tubers obtained from market stalls in the West African countries of Benin, Burkina Faso, Côte d’Ivoire, Ghana, Mali, Nigeria and Togo was determined during the tuber storage periods in 2002 and 2003. A total of 527 yam tuber samples, exhibiting typical nematode (Scutellonema bradys) damage symptoms, were collected and assessed for S. bradys densities. In addition 25,318 tubers on sale in markets were assessed for visual symptoms (except in Nigeria) of nematode damage (S. bradys and Meloidogyne spp.). S. bradys was present in all countries assessed, with greatest (P ≤ 0.05) mean population densities occurring in tubers in Benin (397 g−1), followed by Nigeria (248 g−1) and lowest in Togo (28 g−1). When analysed by agroecological zone, the greatest (P ≤ 0.05) mean S. bradys density was observed in the mid altitude savannah (890 g−1), followed by the southern guinea savannah (488 g−1). S. bradys occurred in lower (P ≤ 0.05) densities on Dioscorea alata (57 g−1) than other yam species, while Dioscorea rotundata was the most abundant yam species encountered. There was considerable variation in S. bradys density between cultivars within country and in some cases between countries. From some cultivars no S. bradys were recovered, even though they presented symptoms of damage. Tubers from Ghana had the greatest (P ≤ 0.05) proportion of tubers visually affected by S. bradys (7.53%), when analysed across yam species and Mali the least (0.28%), while the highest proportion of galled tubers (due to Meloidogyne spp.) was observed in Mali (14.4%) on D. rotundata (19.6%). S. bradys infection, based on visible symptoms, was more evident on D. rotundata (3.8%) than D. alata (0.6%), although 5.18% of yams in the group comprising the unidentified yam species had the greatest mean proportion of visually affected tubers. On market stalls, D. alata (4.73%) and D. rotundata (3.35%) were most affected by visible galling due to Meloidogyne spp.  相似文献   

14.
Lesquerella (Lesquerella fendleri) is a potential alternative crop that is being studied for commercial oilseed production. Understanding the minimum temperatures for germination and seedling growth is important for determining potential areas for lesquerella production. The objectives of this study were to determine the cardinal temperatures for germination and seedling growth, and to screen ecotypes for germination and growth characteristics. A temperature gradient table arrangement was used to observe seed germination over a range of temperatures, and time to germination and shoot appearance. Times to 5 mm root length and 5 mm shoot length were also measured to assess cardinal temperatures for seedling survival and growth. Two different species were examined, L. fendleri and a species we refer to as ‘L. pallida aff.’ because it differed from typical L. pallida plants in chromosome number and in oil quality. We concluded that both germination and growth of L. pallida aff. occurred fastest at 22 °C, whereas L. fendleri germinated earlier at 18 °C, but grew faster at 22 °C. L. pallida aff. also had lower germination than L. fendleri over the range studied. Non-dormant seeds of improved lines of L. fendleri had better performance at temperatures above 22 °C than did unimproved accessions. Lines of L. fendleri selected for high oil content and salt tolerance had similar temperature requirements for germination except for improved line WCL-LO3, the current line being used in production. This line had optimal temperatures 6 °C higher for germination and growth than the other improved lines. Accessions of L. fendleri collected from elevations above 2000 m performed better at warmer temperatures, whereas those collected from elevations below 2000 m tended to perform better at cooler temperatures. Dormant seeds of L. fendleri germinated more quickly at low temperatures and had lower base (<3 °C) and optimal (22 °C) temperatures than non-dormant seeds (>7 °C and 28 °C, respectively). We speculate that this partial dormancy trait allows populations of L. fendleri to exploit a wider range of temperature conditions in the wild in order to thrive in extreme environments.  相似文献   

15.
A 20-year field experiment was employed with the aim of evaluating the effect of tillage systems on biological, chemical and physical aspects of the soil, and to establish whether there was a correlation of these parameters with the incidence of charcoal rot (Macrophomina phaseolina) of soybean and crop yield. The tillage systems evaluated were direct seeding (DS), DS + scarifier (DS + S), minimum tillage (MT) and conventional tillage (CT). DS presented higher values than CT in culturable total fungi (26.33 × 105 vs. 2.33 × 105 CFU g−1 dry soil), total bacteria (182 × 107 vs. 64 × 107 CFU g−1 dry soil), microbial respiration (0.77 mg CO2 g−1 week−1 vs. 0.45 mg CO2 g−1 week−1) and fluorescein diacetate (FDA) hydrolysis (4.17 ug fluorescein g−1 h−1 vs. 1.70 ug fluorescein g−1 h−1 in CT. Fungal and bacterial community fingerprints, by terminal restriction fragment length polymorphism (T-RFLP) analysis, of Intergenic spacer regions of rRNA and 16S rRNA genes, respectively, were influenced by the tillage system. Also FAME (fatty acid methyl ester) profiles showed that microbial community structure in DS and CT was clearly different. DS samples contained significantly higher total microbial biomass than the other tillage treatments, but there were no significant differences in fungal biomass or any consistent trend with respect to stress index. Our results showed that microbial communities were more abundant and active in DS than in CT in response to high nutrient content in soil. Indeed, DS systems presented higher soil OM, total N, K and Ca than CT. Electrical conductivity and aggregate stability (AS) were also improved by DS. Soybean grown in high-quality soil was not affected by charcoal rot, however, under CT, disease incidence in soybean was 54%. These differences were correlated to the higher microbial abundance and activity under DS, the biological component being a key factor determining soil capacity to suppress the soilborne pathogen.  相似文献   

16.
《Field Crops Research》2006,98(1):68-75
Direct seeding instead of transplanting for rice (Oryza sativa L.) has increasingly been used in northern and eastern China because of labor and cost saving. However, poor germinability is still one of the major problems faced in the adoption of direct seeding under low temperature (low temperature germinability: LTG) and anoxia (anoxia germinability: AG) condition. To gain an understanding of the genetic control of seed germinability under these unfavourable conditions, two rice lines, USSR5 (japonica type) and N22 (indica type) and F2 individuals derived from the cross USSR5 × N22 were tested for LTG and AG. USSR5 and N22 differ significantly for both LTG and AG. The LTG of the F2 individuals ranged from 0 to 100% after a 10 days incubation. AG ranged from 0.0 to 4.0 cm shoot length. Based on segregation in the F2 population, a linkage map was constructed using 121 SSR markers. The map covered 1821.5 cM, with a mean inter-marker distance of 16.7 cM. Eleven putative QTLs for LTG were detected, one on each of chromosomes 3–5, 7, 9–11, and four on chromosome 5. The USSR5 alleles in all these QTLs acted to increase LTG. Two QTLs for AG were located on chromosomes 5 and 11, respectively, at both of which the USSR5 alleles acted to increase AG. We propose that USSR5 could make a major contribution to improving LTG and AG in rice breeding programs.  相似文献   

17.
Miscanthus × giganteus is one of the most promising biomass crops for non-food utilisation. Taking into account its area of origin (Far East), its temperature and rainfall requirements are not well satisfied in Mediterranean climate. For this purpose, a research was carried out with the aim of studying the adaptation of the species to the Mediterranean environment, and at analysing its ecophysiological and productive response to different soil water and nitrogen conditions. A split plot experimental design with three levels of irrigation (I1, I2 and I3 at 25%, 50% and 100% of maximum evapotranspiration (ETm), respectively) and three levels of nitrogen fertilisation (0 kg ha−1: N0, 60 kg ha−1: N1 and 120 kg ha−1: N2 of nitrogen) were studied. The crop showed a high yield potential under well-watered conditions (up to 27 t ha−1 of dry matter). M. × giganteus, in Mediterranean environment showed a high yield potential even in very limited water availability conditions (more than 14 t ha−1 with a 25% ETm restoration). A responsiveness to nitrogen supply, with great yield increases when water was not limiting, was exhibited. Water use efficiency (WUE) achieved the highest values in limited soil water availability (between 4.51 and 4.83 g l−1), whilst in non-limiting water conditions it decreased down to 2.56 and 3.49 g l−1 (in the second and third year of experiment, respectively). Nitrogen use efficiency (NUE) decreased with the increase of water distributed (from 190.5 g g−1 of I0 to 173.2 g g−1 of I2); in relation to N fertilisation it did not change between the N fertilised treatments (N1 and N2), being much higher in the unfertilised control (177.1 g g−1). Radiation use efficiency (NUE) progressively declined with the reduction of the N fertiliser level (1.05, 0.96 and 0.86 g d.m. MJ−1, in 1994, and 0.92, 0.91 and 0.69 g d.m. MJ−1, in 1995, for N2, N1 and N0, respectively).  相似文献   

18.
We evaluated the anti-insectan activity of extracts from different vegetative parts of ten plant species native to Uruguay. The selected plants belong to five families: Bignoniaceae: Clytostoma callistegioides, Dolichandra cynanchoides, Macfadyena unguis-cati; Sapindaceae: Dodonaea viscosa, Allophylus edulis, Serjania meridionalis; Lamiaceae: Salvia procurrens, Salvia guaranitica; Solanaceae: Lycium cestroides; and Phytolaccaceae: Phytolacca dioica. The extracts were evaluated in independent bioassays against four insect pests and one beneficial insect. Aphid settling inhibition was evaluated with a grass specialist, Rhopalosiphum padi, and a feeding generalist, Myzus persicae (both Hemiptera: Aphididae). Antifeedant activity was tested with adults of the specialist Epilachna paenulata (Coleoptera: Coccinellidae) and larvae of the generalist Spodoptera littoralis (Lepidoptera: Noctuidae). Finally, contact toxicity was assessed with honey bees, Apis mellifera (Hymenoptera: Apidae). Strong settling inhibition (SI) activity (expressed as %SI, where 100% means complete inhibition by the extract) was found only for the twig extracts of A. edulis (Sapindaceae) against M. persicae (%SI = 77 ± 4). Antifeedant activity (expressed as % of feeding reduction (FR), where 100% means no consumption on extract-treated diet) against E. paenulata was significant for the leaf extracts of L. cestroides (Solanaceae) (%FR = 100 ± 0) as well as of all Bignoniaceae and Sapindaceae species. No extracts were active against S. littoralis larvae, and most of them were innocuous to honey bees, with the exception of L. cestroides and S. meridionalis leaf extracts.  相似文献   

19.
The sustainability of cropping systems can be increased by introducing a cover crop, provided that the cover crop does not reduce the cash crop yield through competition. The cover crop may be sown at the same time as a cash crop in the crop rotation. We carried out an experiment in 1999–2000 and 2000–2001 in the Paris Basin, to analyze the effects of simultaneously sowing winter wheat (Triticum aestivum L.) and red fescue (Festuca rubra L.), a turf grass. Competition between wheat and fescue was analyzed with one variety of red fescue, Sunset, and two varieties of wheat, Isengrain and Scipion, each sown at a density of 150 plants m?2. In this study, we evaluated the effect of undersown fescue on wheat yield and analyzed the competition between the two species in detail. The undersown red fescue decreased wheat yield by about 12% for Isengrain (8.7 t ha?1 for undersown Isengrain versus 9.8 t ha?1 for Isengrain alone) and 7% for Scipion (7.4 t ha?1 for undersown Scipion versus 8.0 t ha?1 for Scipion alone). During the early stages of wheat growth (up to the ‘1 cm ear’ stage, corresponding to stage 30 on Zadoks’ scale), undersown fescue and fescue sown alone grew similarly. However, fescue biomass levels were much lower (5.6 and 4.7 g m?2 for fescue grown alone and undersown fescue) than wheat biomass levels on the undersown plots (120 g m?2 for Isengrain and 111 g m?2 for Scipion). From the e1 stage onwards, the wheat canopy rapidly extended, whereas that of red fescue remained sparse. The time lag between the beginning of the rapid increase in LAI and PAR interception by wheat grown alone and that for fescue grown alone was 590 dd in the second year. This resulted in much slower growth rates for undersown fescue than for undersown wheat. Biomass production rate was therefore low for undersown fescue (12% those of fescue grown alone, on average, at the time of wheat harvest), as were levels of water and nitrogen use. Neither the water deficit that occurred during the second experiment nor the nitrogen nutrition status of the wheat on plots with undersown fescue significantly affected wheat biomass production after anthesis.The global interception efficiency index IG?i indicated that the fraction of the PARo intercepted by the wheat during its growth (255 days) was 0.35.  相似文献   

20.
The color (L*, a*, b* parameters), the total phenols content and the global chemical composition (moisture, protein, fat, carbohydrates and ash) of four fresh varieties of olive leaves (Chemlali, Chemchali, Zarrazi and Chetoui) were determined. Fresh olive leaves are characterized by a green color (greenness parameter, a*, varying from ?5.01 ± 0.26 to ?9.14 ± 1.21), an intermediate moisture content (0.85 to 1.00 g/g dry matter, i.e. 46 to 50 g/100 g fresh matter) and a variable amount of total phenols according to the olive leaf variety (from ≈2.32 to ≈1.40 g caffeic acid/100 g dry matter).Fresh leaves were submitted to blanching and/or infrared drying at 40, 50, 60 and 70 °C in order to be stabilized by reducing their moisture contents. The impact of IR drying temperature on some quality attributes (color, total phenols and moisture rate removal) was evaluated. Nevertheless, the effect of prior blanching treatment on the quality attributes of dried leaves is less significant and it depends on the olive leaf variety. The infrared drying induces a considerable moisture removal from the fresh leaves (more than 85%) and short drying durations (varying from ≈162 at 40 °C to 15 min at 70 °C). IR drying temperature showed a significant effect of on total phenols content and the color of the leaves whatever the leaf variety. In fact, total phenols content of dried olive leaves increased if compared to fresh ones. For example, total phenols of Chemlali leaves increased from 1.38 ± 0.02 (fresh leaves) to 2.13 ± 0.29 (dried at 40 °C) and to 5.14 ± 0.60 g caffeic acid/100 g dry matter (dried at 70 °C). IR drying allows preserving the greenness color of fresh leaves and enhancing their luminosity. It could be suggested for preserving olives leaves before their use in food or cosmetic applications.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号