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1.
《Field Crops Research》2006,95(2-3):412-419
Jasmonic acid (JA) is a plant hormone produced via the octadecanoid pathway from its precursor, linolenic acid. Jasmonates are involved in plant wound responses and defense against insects and fungal elicitors. They can also act as signal molecules in the Bradyrhizobium-soybean symbiosis. Pre-incubation of Bradyrhizobium japonicum inocula with gensitein (Ge), an effective inducer of nodulation genes in this species enhances soybean nodulation, nitrogen fixation and yield under low spring soil temperature field conditions. Since jasmonates are also able to induce nodulation genes and cause the production of lipo-chitooligosaccharides (LCOs) by B. japonicum, we conducted two field experiments, in southwestern Quebec, Canada, to determine whether pre-incubation of B. japonicum with methyl jasmonate (MeJA) alone or in combination with genistein (Ge), prior to inoculation, increased soybean plant dry matter production and grain yield. Experiments at each site used a two factor randomized complete block design (RCBD) with four replicates. Two B. japonicum strains (USDA3 and 532C) and four inducer molecule treatments [control, Ge (20 μM), MeJA (50 μM), and Ge + MeJA (20 μM + 50 μM)] were used in the study. The bacterial cultures were induced for 24 h with the inducer molecules and then applied into the furrows at the time of planting. Both Ge and MeJA, alone or in combination, increased plant growth, dry matter accumulation, and grain yield. This study showed that MeJA, alone or in combination with Ge, can be used to promote soybean plant growth and grain yield under short season field conditions.  相似文献   

2.
《Field Crops Research》2006,96(1):90-97
Low native nitrogen (N) and phosphorus (P) coupled with imbalanced nutrient application is a major constraint limiting productivity of intercropping systems on Vertisols of the semi-arid tropical India. In a 3-year field experiment competition behaviour of component crops for nutrients use in soybean/pigeonpea intercropping system was assessed based on relative yield (RY), relative nitrogen yield (RNY) and relative phosphorus yield (RPY) under three nutrient levels (0 NPK, 100% NPK (N:P:K = 30:26:25 kg ha−1) and 100% NPK + 4 t FYM ha−1). The result showed that before soybean harvest, the RY and RNY of soybean were greater (1.0) than the corresponding values of RY and RNY of pigeon pea (0.6). This implied that competition exists for soil N between the component crops during the first half of the cropping system. It was observed that soybean harvest did not coincide with peak flowering of pigeonpea, the stage when biological nitrogen fixation (BNF) was maximum. Thus, BNF dependency of pigeonpea was low before soybean harvest and the plants suffered from N deficiency more when no fertilizer-N was applied and diminished at a high-N level. Pigeon pea attained its peak flowering after the harvest of soybean and increased its dependency on BNF when soil N was exhausted by soybean. Thus, after the harvest of soybean, RY and RNY of pigeon pea gradually increased and approached 1.0 at maturity at all nutrient levels. The RPY values showed that phosphorus was not the limiting factor to any of the crop in the system even if it was not applied. The study thus suggests that in the soybean/pigeonpea intercropping system, N is a limiting factor for growth of pigeonpea intercrop during the first half of its growth and application of 100% NPK (30 kg N) + 4 t FYM could meet N demand of pigeonpea in N deficient soils as this nutrient management option gave higher yield, root length density and profit under soybean/pigeonpea intercropping system than 100% NPK and control.  相似文献   

3.
《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   

4.
Stigma exsertion is an important trait for outcrossing ability in rice. Stigma exsertion rate (SER) of male sterile lines (MSLs) is a key factor affecting F1-seed production in hybrid rice. In this study, seven QTLs for SER were detected on five chromosomes using a set of single-segment substitution lines (SSSLs) derived from O. glaberrima. Three of the QTLs were mapped in the estimated intervals of 92.5–333.0 kb. qSER-5 was located in a substitution segment of 92.5 kb. qSER-1b and qSER-8b were respectively limited to 333.0 kb and 107.5 kb by secondary substitution mapping. qSER-1b and qSER-3 had bigger additive effects of 11.5% and 11.9%, respectively, while the other five QTLs had smaller additive effects from 5.7% to 8.6%. Open reading frames were identified in the regions of qSER-5 and qSER-8b in O. sativa and O. glaberrima genomes. Fine mapping of the QTLs laid a foundation for the cloning of genes, and QTLs for SER will be used to develop MSLs with strong ability of outcrossing.  相似文献   

5.
《Field Crops Research》2005,91(2-3):217-229
Soybean [Glycine max (L.) Merr.] seed is a major source of protein for animal feed and oil for human consumption. Selection within elite soybean cultivars for the improvement of agronomic and seed traits is assumed to be ineffective due to the belief that cultivars are highly homogeneous. Previously reported data suggest that latent variation among the single plant selections within a cultivar exists and that mechanisms that generate de novo variation may also be present. The main objective of this study was to perform divergent single-plant selection at ultra-low plant density and investigate the presence of genetic variation for seed protein and oil within three elite soybean cultivars. A secondary objective was to investigate the variation for fatty acid composition. In 1995, single plants from the three cultivars were grown in a honeycomb design using a plant-to-plant spacing of 0.9 m. A total of 333 plants from ‘Benning’, 392 plants from ‘Haskell’, and 371 plants from ‘Cook’ were evaluated. Divergent single-plant selection for protein and oil content was performed to select a total of 20 plants for high or low protein and 20 plants for high or low oil from each cultivar. The selected plants were further evaluated in replicated row-plot experiments for 3 years. Our results indicate that single-plant selection at low plant density was successful in discovering significant variation for seed protein and oil within each of the three soybean cultivars. For protein content, the magnitude of intra-cultivar variation between the highest- and lowest-protein lines averaged 19 g kg−1 across the three cultivars and ranged from 13 to 24 g kg−1. For oil composition, the magnitude of variation between the most divergent lines averaged 12 g kg−1 across the three cultivars and ranged from 9 to 14 g kg−1. Significant variation among the selected progeny lines was also discovered for specific fatty acid composition. The magnitude of intra-cultivar variation averaged from 6 to 29 g kg−1 across the five fatty acids of soybean. The genetic variation discovered within the soybean cultivars is most likely due to latent variation and/or newly created variation. Our data provide evidence that single-plant selection at ultra-low plant density within elite cultivars can be effective in improving the seed composition of a soybean cultivar.  相似文献   

6.
《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   

7.
《Field Crops Research》2006,99(1):67-74
An inverse relationship between soybean [Glycine max (L.) Merr.] seed protein and oil concentration is well documented in the literature. A negative correlation between protein and yield is also often reported. The objective of this study was to determine the effect of high rates of N applied at planting on seed protein and oil. Nitrogen was surface-applied at soybean emergence at rates of 290 kg ha−1 in 2002, 310 kg ha−1 in 2003, and 360 kg ha−1 in 2004. Eight cultivars ranging from Maturity Group II–IV were evaluated under the Early Soybean Production System (ESPS). However, not all cultivars were evaluated in all 3 years. Glyphosate herbicide was used in all 3 years and a non-glyphosate herbicide treatment was applied in 2002. Cultivars grown in 2003 were also evaluated under an application of 21.3 kg ha−1 of Mn. All cultivar, herbicide, and Mn treatments were evaluated in irrigated and non-irrigated environments with fertilizer N (PlusN treatment) or without fertilizer N (ZeroN treatment). When analyzed over all management practices (years, cultivars, herbicide, and Mn treatments), the PlusN treatment resulted in a significant decrease in protein concentration (2.7 and 1.9%), an increase in oil concentration (2.2 and 2.7%), and a decrease in the protein/oil ratio (4.7 and 4.6%) for the irrigated and non-irrigated environments, respectively. However, the overall protein and oil yield increased with the application of fertilizer N at planting (protein: 5.0% irrigated, 12.7% non-irrigated and oil: 9.9% irrigated and 18.9% non-irrigated). These increases were due to the increase in seed yield with the application of large amounts of fertilizer at planting. Additionally, a significant correlation (r = 0.45, P = 0.0001) was found between seed protein concentration and seed yield. No significant correlation was found between seed oil concentration and seed yield. The data demonstrate the inverse relationship between protein and oil and indicate that large amounts of N applied at planting do not change this relationship.  相似文献   

8.
Genome-wide association study (GWAS) was performed for 16 agronomic traits including nitrogen use efficiency (NUE) and yield-related components using a panel of 190 mainly japonica rice varieties and a set of 38 390 single nucleotide polymorphism (SNP) markers. This panel was evaluated under rainfed upland conditions in Madagascar in two consecutive cropping seasons with two contrasted nitrogen input levels. Using another set of five grain traits, we identified previously known genes (GW5, GS3, Awn1 and Glabrous1), thus validating the pertinence and accuracy of our datasets for GWAS. A total of 369 significant associations were detected between SNPs and agronomic traits, gathered into 46 distinct haplotype groups and 28 isolated markers. Few association signals were identified for the complex quantitative trait NUE, however, larger number of quantitative trait loci (QTLs) were detected for its component traits, with 10 and 2 association signals for nitrogen utilization efficiency and nitrogen uptake efficiency, respectively. Several detected association signals co-localized with genes involved in nitrogen transport or nitrogen remobilization within 100 kb. The present study thus confirmed the potential of GWAS to identify candidate genes and new loci associated with agronomic traits. However, because of the quantitative and complex nature of NUE-related traits, GWAS might have not captured a large number of QTLs with limited effects.  相似文献   

9.
Cover crops can provide changes in soil chemical and physical properties, which could allow a sustainable development of soybean and upland rice rotation in Brazilian Cerrado. The objective of this study was to determine the effects of cover crops(cultivated in the offseason) in the soybean-upland rice rotation(cultivated in the summer season) on the soil chemical and physical properties, yield components and grain yield of the cash crops. The experimental design was a randomized block design in factorial scheme 4 × 2 with six replications. Treatments were composed by four cover crops: fallow, millet(Pennisetum glaucum) + Crotalaria ochroleuca, millet + pigeon pea(Cajanus cajans), and millet + pigeon pea + Urochola ruziziensis in the offseason with one or two cycles of cover crops, with rice(Oryza sativa)or soybean(Glycine max) in the summer season. Cover crops alone provided no changes in soil chemical properties. However, the rotation cover crops/cash crops/cover crops/cash crops reduced p H, Al and H + Al and increased Ca, Mg, K and Fe contents in the soil. The cover crops millet + pigeon pea and millet + pigeon pea + U. ruziziensis improved soil physical properties in relation to fallow,especially in the 0–0.10 m soil layer. In spite of the improvement of the soil physical properties after two years of rotation with cover crops and cash crops, the soil physical quality was still below the recommended level, showing values of macroporosity, S index and soil aeration capacity lower than 0.10 m3/m3, 0.035 and 0.34, respectively. Upland rice production was higher under mixtures of cover crops than under fallow, mainly because of soil physical changes done by these mixtures of cover crops.Soybean grain yield was similar under all cover crops tested, but was higher after the rotation cover crops/upland rice/cover crops than after only one cycle of cover crops.  相似文献   

10.
Fast protein liquid chromatography has been developed for purification of high-molecular-weight glutenin subunits HMW-GSs from wheat flour. Flour samples from four wheat cultivars with different HMW-GS alleles at Glu-A1, Glu-B1 and Glu-D1 loci were used to establish the method. The column material used was Resource™ Phe, and the optimal elution was with a gradient formed with buffer A [0.05 M Tris–HCl containing 4 M urea and 0.25 M (NH4)2SO4, pH 8.0] and buffer B [0.05 M Tris–HCl containing 4 M urea (pH 8.0)] at a flow rate of 0.5 ml/min. A pure single 1Dx-, 1Bx- HMW-GS, and all the y-type HMW-GSs present in one genotype can be reliably separated in a single step.  相似文献   

11.
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12.
《Field Crops Research》2001,70(1):27-41
Many Australian cotton growers now include legumes in their cropping system. Three experiments were conducted between 1994 and 1997 to evaluate the rotational effects of winter or summer legume crops grown either for grain or green manuring on following cotton (Gossypium hirsutum L.). Non-legume rotation crops, wheat (Triticum aestivum) and cotton, were included for comparison. Net nitrogen (N) balances, which included estimates of N associated with the nodulated roots, were calculated for the legume phase of each cropping sequence. Faba bean (Vicia faba — winter) fixed 135–244 kg N ha−1 and soybean (Glycine max — summer) fixed 453–488 kg N ha−1 and contributed up to 155 and 280 kg fixed N ha−1, respectively, to the soil after seed harvest. Green-manured field pea (Pisum sativum — winter) and lablab (Lablab purpureus — summer) fixed 123–209 and 181–240 kg N ha−1, respectively, before the crops were slashed and incorporated into the topsoil.In a separate experiment, the loss of N from 15N-labelled legume residues during the fallow between legume cropping and cotton sowing (5–6 months following summer crops and 9 months after winter crops) was between 9 and 40% of 15N added; in comparison, the loss of 15N fertilizer (urea) applied to the non-legume plots averaged 85% of 15N added. Little legume-derived 15N was lost from the system during the growth of the subsequent cotton crop.The improved N fertility of the legume-based systems was demonstrated by enhanced N uptake and lint yield of cotton. The economic optimum N fertilizer application rate was determined from the fitted N response curve observed following the application of N fertilizer at rates between 0 and 200 kg N ha−1 (as anhydrous ammonia). Averaged over the three experiments, cotton following non-legume rotation crops required the application of 179 kg N ha−1, whilst following the grain- and green-manured legume systems required only 90 and 52 kg N ha−1, respectively.In addition to improvements in N availability, soil strength was generally lower following most legume crops than non-legume rotation crops. Penetrometer resistance during the growth of the subsequent cotton crop increased in the order faba bean, lablab, field pea, wheat, cotton, and soybean. It is speculated that reduced soil strength contributed to improvement in lint yields of the following cotton crops by facilitating the development of better root systems.  相似文献   

13.
《Field Crops Research》1999,64(3):287-291
Osmotic adjustment (OA) is generally considered an important component of drought resistance. Several reports by J.M. Morgan [Morgan, J.M., 1983. Osmoregulation as a selection criterion for drought tolerance in wheat. Aust. J. Agric. Res. 34, 607–614; 1992. Osmotic components and properties associated with genotypic differences in osmoregulation in wheat. Aust. J. Plant Physiol. 19, 67–76; 1995. Growth and yield of wheat lines with differing osmoregulative capacity at high soil water deficit in seasons of varying evaporative demand. Field Crops Res. 40, 143–152; Morgan, J.M., Condon, A.G., 1986. Water-use, grain yield and osmoregulation in wheat. Aust. J. Plant Physiol. 13, 523–532] from Australia concluded that consistent genetic differences in OA existed among wheat cultivars and that high OA cultivars tended to yield better than low OA cultivars under drought stress. Our study was performed to assess his results with his and other genetic materials.Two of Morgan’s spring wheat lines with high OA (‘H.Osm-134’) and low OA (‘L.Osm-136’) capacity in addition to eight other diverse spring wheat cultivars were tested for OA and plant production when grown in small plots under a rain exclusion shelter at Bet Dagan, Israel in 1996. OA of five of these cultivars (including Morgan’s lines) was also measured in two independent greenhouse tests in 1997 (Israel) and 1998 (Texas).The five cultivars differed significantly and ranked consistently for OA in all tests. No significant cultivar by test interaction for OA was revealed. OA was well correlated across cultivars between tests. The significantly higher OA capacity of H.Osm-134 as compared with L.Osm-136 was repeated in all tests. OA of all ten cultivars was positively correlated with biomass (r = 0.73; p = 0.02) and yield (r = 0.55; p = 0.09) under pre-flowering drought stress in the rain exclusion shelter. H.Osm-134 line performed significantly (p ≤ 0.05) better than L.Osm-136 line for both biomass and yield under drought stress. We therefore support Morgan’s results and conclude that consistent differences in OA exist among wheat cultivars and that these differences can be associated with plant production under pre-flowering drought stress.  相似文献   

14.
《Field Crops Research》1999,63(3):225-236
In rainfed agriculture, climatic variability has profound effects on the performance of management systems in improvements of productivity and use of natural resources. A field study was conducted on a Vertic Inceptisol during 1995–1997 seasons at the ICRISAT Center, Patancheru, India, to study the effect of two landforms, i.e., broadbed-and-furrow (BBF) and flat, and two soil depths (shallow and medium-deep) on crop yield and water balance of a soybean–chickpea rotation. Using two seasons experimental data, a soybean–chickpea sequencing model was evaluated and used to extrapolate the results over 22 years of historical weather records. The simulation results showed that in 70% of years total runoff for BBF was greater than 35 mm (range 35–190 mm) compared to greater than 60 mm (range 60–260 mm) for flat on the shallow soil. In contrast on the medium-deep soil it was greater than 70 mm (range 70–280 mm) for BBF compared to greater than 80 mm (range 80–320 mm) for the flat landform. The decrease in runoff on BBF resulted in a concomitant increase in deep drainage for both soils. In 70% of years, deep drainage was greater than 60 mm (range 60–390 mm) for the shallow soil and ranged from 10 to 280 mm for the medium-deep soil. In 70% of years, the simulated soybean yields were greater than 2200 kg ha−1 (range 2200–3000 kg ha−1) and were not influenced by landform or soil depth. In the low rainfall years, yields were marginally higher for the BBF than for the flat landform, especially on the shallow soil. Simulated chickpea yields were higher for the medium-deep soil than for the shallow soil. In most years, marginally higher chickpea yields were simulated for the BBF than for the flat landform on both soil types. In 70% of years, the chickpea yields were greater than 500 kg ha−1 (range 500–1500 kg ha−1) for the shallow soil, and greater than 800 kg ha−1 (range 800–1960 kg ha−1) for the medium-deep soil. Total productivity of soybean–chickpea rotation was greater than 3000 kg ha−1 (range 3000–4150 kg ha−1) for the shallow soil and greater than 3450 kg ha−1 (range 3450–4700 kg ha−1) for the medium-deep soil in 70% of years. These results showed that in most years BBF, landform increased rainfall infiltration into the soil and had marginal effect on yields of soybean and chickpea. Crop yields on Vertic Inceptisols can be further increased and sustained by adopting appropriate rain water management practices for exploiting surface runoff and deep drainage water as supplemental irrigation to crops in a watershed setting.  相似文献   

15.
《Field Crops Research》2002,76(1):25-43
Root morphological characteristics are known to be important in the drought resistance of some rice (Oryza sativa L.) varieties. The identification of quantitative trait loci (QTLs) associated with root morphology and other drought resistance-related traits should help breeders produce more drought resistant varieties. Stability in the expression of root growth QTL across rooting environments is critical for their use in breeding programs. A greenhouse experiment in which a mapping population of 140 recombinant inbred lines and the parental varieties Bala and Azucena were grown in glass-sided soil chambers and evaluated for root growth and water uptake was conducted. In each of 2 years, two treatments were used; an early water-deficit (WD0) in which seeds were sown into wet soil but received no more water, and a late water-deficit (WD49) in which the plants were watered for 49 days and then received no water for a week. The major differences between treatments and years in dry matter partitioning and root growth traits are reported elsewhere. Here, the identification of QTLs for root growth traits by composite interval mapping is described. At LOD>3.2, there were six QTLs for the weight of roots below 90 cm and maximum root length, 11 for root to shoot ratio, 12 for the number of roots past 100 cm, and 14 for root thickness. A total of 24 regions were identified as containing QTLs (these regions often contained several QTLs identified for different root traits). Some were revealed only in individual experiments and/or for individual traits, while others were common to different traits or experiments. Seven QTLs, on chromosomes 1, 2, 4, 7, 9 (two QTLs) and 11, where considered particularly noteworthy. The complex results are discussed in the context of previously reported QTLs for root growth in other populations, the interaction between QTL with the environment and the value of QTLs for breeding.  相似文献   

16.
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   

17.
《Field Crops Research》1999,63(3):237-246
Using data from large, grower-managed fields we investigated the variation in yield of dryland soybean in an area with low and variable summer rainfall, and soils that are variable in depth and poor in phosphorus (P). First, using data from unfertilised, wide-row (0.7 m) crops grown under standard management between 1989 and 1992 (Series 1), we quantified the relationship between yield and W, a rainfall-based estimate of water availability during the period of pod and grain set. Separate functions were established for deep (depth ≥ 1 m) and shallow soils (0.75 m ≥ depth ≥ 0.5 m). Second, we partially tested these functions using two independent data sets (Series 2 and 3). Third, we evaluated the effects on yield of large (18 kg P ha−1, Series 4) or moderate doses of P fertiliser (8–12 kg P ha−1) in narrow-row crops (0.35 m, Series 5). To investigate water × management interaction we (i) calculated ΔY, the difference between actual yield in Series 4 and 5 and yield calculated with the functions derived from Series 1, and (ii) tested the association between ΔY and actual W. In a set of 24 crops (Series 1), yield varied between 2.1 and 3.1 t ha−1 in deep soils and between 1.3 and 2.6 t ha−1 in shallow soils; non-linear functions described fairly well, the response of yield to W. Fertilisation with 18 kg P ha−1 increased yield by 0.6 t ha−1 irrespective of water availability. The combination of narrow rows and a moderate dose of fertiliser increased yield in 73% of crops in deep soil but only in 53% of crops in shallow soil. There was a positive association between ΔY and W in deep soil but no relationship between these variables in shallow soil. Yield responses to management were thus differentially affected by rainfall in deep and shallow soils.  相似文献   

18.
《Field Crops Research》1999,63(3):211-224
Vertic Inceptisols are prone to land degradation because of excessive run-off and soil erosion during the rainy season. Productivity of soybean-based systems on these soils needs to be improved and sustained by better management of natural resources, particularly soil and water. During 1995–1997 a field study was conducted in Peninsular India on a Vertic Inceptisol watershed to study the effect of two soil depths, namely shallow (<50 cm soil depth) and medium-deep (≥50 cm soil depth) and two landform treatments, namely flat and broadbed-and-furrow (BBF) systems, on productivity and resource-use efficiency of soybean–chickpea rotation (soybean in rainy season followed by chickpea in post-rainy season). Soybean grown on flat landform on medium-deep soil had a higher leaf area index and more light interception compared to the soybean grown on the BBF landform. This resulted in an increase in mean seed yield for the flat landform (2120 kg ha−1) compared to the BBF landform (1870 kg ha−1). However, the landform treatments on shallow soil did not affect soybean yields. The soybean yield was higher on the medium-deep soil (1760 kg ha−1) than on the shallow soil (1550 kg ha−1) during 1995–1996, but were not different during 1996–1997. In both years chickpea yields and total system productivity (soybean + chickpea yields) were greater on medium-deep soil than on the shallow soil. Total run-off was higher on the flat landform (25% of seasonal rainfall) than on the BBF landform (20% of seasonal rainfall). This concomitantly increased profile water content (10–30 mm) of both soils in BBF compared to the flat landform treatment during 1995–1996, but not during 1996–1997. Deep drainage was higher in the BBF landform than in flat, especially for the shallow soil. Across landforms and soil depths, water use (evapotranspiration) by soybean–chickpea rotation during 1996–1997 ranged from 496 to 563 mm, which accounted for 54–61% of the rainfall. These results indicate that while the BBF system is useful in decreasing run-off and increasing infiltration of rainfall on Vertic Inceptisols, there is a need to increase light use by soybean on BBF during the rainy season to increase its productivity. A watershed-based farming system needs to be adopted to capture significant amount of rain water lost as run-off and deep drainage. The stored water can be used for supplemental irrigation to increase productivity of soybean-based systems leading to overall increases in resource-use efficiency, crop productivity, and sustainability.  相似文献   

19.
《Field Crops Research》2001,71(1):47-55
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20.
Vanilla is a large genus of about 110 species in the orchid family (Orchidaceae), including the species Vanilla planifolia from which commercial vanilla flavoring is derived. Since most species of vanilla are considered rare and endangered there is an urgent need to conserve them through genetic analysis and propagation/conservation studies on this crop.The present study investigated the genetic diversity among nine leafy- and leaf-less Vanilla species employing 30 decamer RAPD primers and 10 ISSR primers. The species under study were diverse and displayed a range of variability (0–66% and 0–81% for RAPD and ISSR, respectively). A total of 154 RAPD polymorphic markers (83.24%, h = 0.378) and 93 ISSR polymorphic markers (86.11%, h = 0.363) were used to generate a genetic similarity matrix followed by the cluster analysis. Specific groupings were revealed by each cluster analysis with slight variation between two different markers. Among the nine species studied, V. planifolia, Vanilla aphylla and Vanilla tahitensis revealed very low level of variation within their collections, thus indicating a narrow genetic base. The large genetic distance of Vanilla andamanica from other species suggests its different origin. A close genetic affinity was observed between the pairs V. planifolia, V. tahitensis and Vanilla albida, V. aphylla. These are the first comparative results for RAPD and ISSR reporting inter-relationship among nine cultivated, wild and hybrid Vanilla species.  相似文献   

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