Changes in the physiology and feed quality of cocksfoot (Dactylis glomerata L.) during regrowth

Abstract A glasshouse study was undertaken to determine the physiological and morphological changes in cocksfoot (Dactylis glomerata L.) during regrowth after defoliation. Individual plants were arranged in a mini‐sward in a randomized complete block design. Treatments involved harvesting each time one new leaf had expanded (one‐leaf stage), up to the six‐leaf stage, with the plants separated into leaf, stubble (tiller bases) and roots. Stubble and root water‐soluble carbohydrate (WSC), stubble and leaf dry matter (DM), tiller number per plant and leaf quality (crude protein (CP), estimated metabolizable energy (ME) and mineral content) were measured to develop optimal defoliation management of cocksfoot‐based pastures. WSC concentration in stubble and roots was highest at the five‐ and six‐leaf stages. Mean WSC concentration (g kg^?1 DM) was greater in stubble than roots (32·7 ± 5·9 vs. 9·4 ± 1·5 respectively). There was a strong positive linear relationship between plant WSC concentration and leaf DM, root DM and tillers per plant after defoliation (Adj R² = 0·72, 0·88 and 0·95 respectively). Root DM plant^?1 and tiller DM tiller^?1 decreased immediately following defoliation and remained low until the three‐leaf stage, then increased from the four‐leaf stage. Tillers per plant remained stable until the four‐leaf stage, after which they increased (from 9·9 ± 0·5 to 15·7 ± 1·0 tillers plant^?1). Estimated metabolizable energy concentration (MJ kg^?1 DM) was significantly lower at the six‐leaf stage (11·01 ± 0·06) than at any previous leaf regrowth stage, whereas CP concentration (g kg^?1 DM) decreased with regrowth to the six‐leaf stage. Both the levels of ME and CP concentrations were indicative of a high quality forage throughout regrowth (11·37 ± 0·04 and 279 ± 8·0 for ME and CP respectively). Results from this study give a basis for determining appropriate criteria for grazing cocksfoot‐based pastures. The optimal defoliation interval for cocksfoot appears to be between the four‐ and five‐leaf stages of regrowth. Delaying defoliation to the four‐leaf stage allows time for replenishment of WSC reserves, resumption of root growth and an increase in tillering, and is before herbage is lost and quality falls due to onset of leaf senescence.     

Effect of defoliation management, based on leaf stage, on perennial ryegrass (Lolium perenne L.), prairie grass (Bromus willdenowii Kunth.) and cocksfoot (Dactylis glomerata L.) under dryland conditions. 1. Regrowth, tillering and water-soluble carbohydrate concentration

A field study was undertaken between April 2003 and May 2004 in southern Tasmania, Australia to quantify and compare changes in herbage productivity and water‐soluble carbohydrate (WSC) concentration of perennial ryegrass (Lolium perenne L.), prairie grass (Bromus willdenowii Kunth.) and cocksfoot (Dactylis glomerata L.) under a defoliation regime based on leaf regrowth stage. Defoliation interval was based on the time taken for two, three or four leaves per tiller to fully expand. Dry‐matter (DM) production and botanical composition were measured at every defoliation event; plant density, DM production per tiller, tiller numbers per plant and WSC concentration were measured bimonthly; and tiller initiation and death rates were monitored every 3 weeks. Species and defoliation interval had a significant effect (P < 0·05) on seasonal DM production. Prairie grass produced significantly more (P < 0·001) DM than cocksfoot and ryegrass (5·7 vs. 4·1 and 4·3 t DM ha^?1 respectively). Plants defoliated at the two‐leaf stage of regrowth produced significantly less DM than plants defoliated at the three‐ and four‐leaf stages, irrespective of species. Defoliation interval had no effect on plant persistence of any species during the first year of establishment, as measured by plant density and tiller number. However, more frequent defoliation was detrimental to the productivity of all species, most likely because of decreased WSC reserves. Results from this study confirmed that to maximize rates of regrowth, the recommended defoliation interval for prairie grass and cocksfoot is the four‐leaf stage, and for perennial ryegrass between the two and three‐leaf stages.     

Modelling the concentrations of nitrogen and water-soluble carbohydrates in grass herbage ingested by cattle under strip-grazing management

There is scope of increasing the nitrogen (N) efficiency of grazing cattle through manipulation of the energy and N concentrations in the herbage ingested. Because of asymmetric grazing by cattle between individual plant parts, it has not yet been established how this translates into the concentrations of N and water‐soluble carbohydrates (WSC) in the herbage ingested. A model is described with the objective of assessing the efficacy of individual tools in grassland management in manipulating the WSC and N concentrations of the herbage ingested by cattle under strip‐grazing management throughout the growing season. The model was calibrated and independently evaluated for early (April), mid‐ (June, regrowth phase) and late (September) parts of the growing season. There was a high correlation between predicted and observed WSC concentrations in the ingested herbage (R² = 0·78, P < 0·001). The correlation between predicted and observed neutral‐detergent fibre (NDF) concentrations in the ingested herbage was lower (R² = 0·49, P < 0·05) with a small absolute bias. Differences in the N concentration between laminae and sheaths, and between clean patches and fouled patches, were adequately simulated and it was concluded that the model could be used to assess the efficacy of grassland management tools for manipulating the WSC and N concentrations in the ingested herbage. Model application showed that reduced rates of application of N fertilizer and longer rotation lengths were effective tools for manipulating herbage quality in early and mid‐season. During the later part of the growing season, the large proportion of area affected by dung and urine reduced the effect of application rate of N fertilizer on herbage quality. In contrast, relative differences between high‐sugar and low‐sugar cultivars of perennial ryegrass were largest during this period. This suggests that high‐sugar cultivars may be an important tool in increasing N efficiency by cattle when risks of N losses to water bodies are largest. The model output showed that defoliation height affects the chemical composition of the ingested herbage of both the current and the subsequent grazing period.     

Ecotypic differences and performance of the genetic resources of cocksfoot (Dactylis glomerata L.) in north-west Spain

Quantitative traits and allozymes were used in two experiments to clarify the ecotypic differentiation of natural cocksfoot ( Dactylis glomerata ) populations from north-west Spain. Thirty-nine populations belonging to the four main ecotypes in Galicia were cultivated in two field experiments. In the first experiment, there were significant differences between ecotypes for heading date, flag leaf length, growth habit and vigour. Coastal populations were the least infected by rust. In the second experiment, allozyme markers presumed to be diagnostic for ssp. glomerata vs. izcoi ( TO1 1·00, TO1 1·03) were found in all populations studied (ten tetraploids and one diploid izcoi ). This suggests that gene flow occurs between coastal and interior populations. Culm and panicle lengths of tetraploids (without application of fertilizer) were inside the izcoi range in 1997, but some plants from all populations exceeded it in 1998. It is concluded that ssp. izcoi also occurs on the coast. Populations with a high level of complementary seasonal growth were detected.     

The effect of age of the sward on the relationship between water-soluble carbohydrate accumulation and drought survival in two contrasted populations of cocksfoot (Dactylis glomerata L.)

In Mediterranean drylands, drought survival is a major factor of persistence of perennial forage grasses. In the island of Corsica, plant survival and changes in water-soluble carbohydrate (WSC) content were investigated in first- and second-year swards of two populations of cocksfoot: Lutetia, a drought-sensitive cultivar, and KM2, a drought-resistant Mediterranean population. When subjected to a moderate drought under a rain-shelter. Lutetia died whereas KM2 recovered with low mortality. The sensitivity of survival to the date of defoliation is emphasized. In first-year swards, WSC content in entire tiller bases at the end of the drought was four times greater in KM2 than in Lutetia and was correlated with differential recovery in the two populations. Conversely in second-year swards, no relationship between WSC content in entire tiller bases and recovery was found. However, WSC content in the youngest living enclosed leaves of KM2 accumulated to reach 63% of dry matter (DM) whereas in Lutetia WSC fell below 30% of DM; this factor might be associated with its survival. In both tiller bases and enclosed leaves, sucrose content and the content of large fructans tended to increase over the summer, whereas monosaccharide content declined. Enclosed leaves are the main survival organs: their role as a sink for translocated material (sucrose) and as a site of fructan accumulation is discussed.     

Effects of 5 years of digestate application on biomass production and quality of cocksfoot (Dactylis glomerata L.)

Anaerobic digestion of biomass produces biogas for combustion and also provides a residual digestate. Although sometimes regarded as a waste product, the nutrient‐rich chemical composition of digestate makes it a potential organic fertilizer for agriculture. The goal of this study was to evaluate the effectiveness of digestate as a fertilizer on the biomass yield and chemical composition of cocksfoot (Dactylis glomerata L.). In a 5‐year small‐plot field experiment digestate fertilization treatments supplying 90, 180, 270, 360 and 450 kg N ha^?1 were compared with untreated plots and plots fertilized with 180 kg N ha^?1 of mineral N fertilizer. Swards fertilized with digestate produced higher biomass yield compared with the control. The same rate of nitrogen fertilizer (180 kg N ha^?1) supplied as digestate and from mineral fertilizers gave similar results on biomass yield. Herbage in swards fertilized with digestate contained less nitrogen, but the C:N ratio was much more suitable for biogas production. Digestate fertilization resulted in higher concentrations of cellulose and hemicellulose in biomass and lower contents of the inhibitors of anaerobic digestion—sulphur, calcium, magnesium and phosphorus—compared with those of swards receiving mineral fertilizers.     

Interaction between water-soluble carbohydrate reserves and defoliation severity on the regrowth of perennial ryegrass (Lolium perenne L.)-dominant swards

A field-study was undertaken in Hamilton, New Zealand to determine if there was an interaction between water-soluble carbohydrate (WSC) reserve content and defoliation severity on the regrowth of perennial ryegrass-dominant swards during winter. Perennial ryegrass plants with either low or high WSC content were obtained by varying the defoliation frequency. At the third defoliation at the one-leaf stage and at the first defoliation at the three-leaf stage (harvest H₁), swards were mown with a rotary lawnmower to residual stubble heights of 20, 40 or 60 mm. All swards were then allowed to regrow to the three-leaf stage before again defoliating to their treatment residual stubble heights (H₂). Frequently defoliated plants contained proportionately between 0·37 and 0·48 less WSC in the stubble after defoliation, depending on the severity of defoliation. There was no interaction between WSC content and defoliation severity for herbage regrowth between harvests H₁ and H₂. Herbage regrowth was lower from swards containing low WSC plants compared with high WSC plants (2279 vs. 2007 kg DM ha⁻¹). Furthermore, swards defoliated to 20 or 40 mm had greater herbage regrowth compared with those defoliated to 60 mm (2266, 2249 and 1914 kg DM ha⁻¹ for swards defoliated to residual stubble heights of 20, 40 and 60 mm, respectively). Regrowth of perennial ryegrass was positively correlated with post-defoliation stubble WSC content within defoliation severity treatment, implying that WSC contributed to the defoliation frequency-derived difference in herbage yield. However, the effect of defoliation severity on herbage regrowth was not associated with post-defoliation stubble WSC content.     

The morphological and physiological responses of perennial ryegrass (Lolium perenne L.), cocksfoot (Dactylis glomerata L.) and tall fescue (Festuca arundinacea Schreb.; syn. Schedonorus phoenix Scop.) to variable water availability

There is a growing interest in the use of deficit irrigation and perennial pasture species other than perennial ryegrass (Lolium perenne L.) in temperate agriculture, in response to the decreasing availability of irrigation water. Deficit irrigation requires an understanding of plant responses to drought stress to ensure maximum dry‐matter return on water applied. A glasshouse study was undertaken to investigate some of the morphological and physiological responses of perennial ryegrass, cocksfoot (Dactylis glomerata L.) and tall fescue (Festuca arundinacea Schreb.; syn. Schedonorus phoenix Scop.) to varied moisture availability. One water treatment involved frequent applications of water to maintain a soil water potential of approximately ?10 kPa (100% treatment), and three other treatments involved applications at the same frequency, but using 33, 66 or 133% of the water applied in the 100% treatment. The water treatments continued over two plant regrowth cycles, followed by a ‘recovery’ phase of a single regrowth cycle during which all plants received the same water allocation as the 100% treatment. Depletion and replenishment of stubble water‐soluble carbohydrate (WSC) differed between the three species in response to soil moisture availability. By the second regrowth cycle, stubble WSC concentration and content in moisture‐stressed cocksfoot plants had increased, followed by a decrease during the subsequent recovery phase when the stored WSC reserves were utilized to support regrowth. The changes in stubble WSC reserves corresponded to the maintenance of relatively stable (i.e. the smallest reduction in leaf DM in response to moisture stress), but consistently lower DM production for cocksfoot compared with the other species. In contrast, moisture stress had no effect on the stubble WSC reserves of perennial ryegrass and tall fescue, with the exception of a significant decrease in WSC concentration under the 33% water treatment for perennial ryegrass. Perennial ryegrass achieved an intermediate DM yield and maintained positive growth rates throughout the study, even when watered at 33% of the requirement for optimal soil moisture levels. However, a more pronounced reduction in leaf DM in plants under moisture stress compared with the other species, combined with declining WSC reserves and the death of daughter tillers, highlighted the vulnerability of perennial ryegrass to poor persistence under prolonged drought conditions. Tall fescue appeared to have the greatest scope under moisture stress in terms of maintaining productivity and displaying attributes that contribute to persistence. Its leaf DM was consistently greater than that of the other species, displaying a smaller decline in growth under water stress compared to perennial ryegrass and an ability to recover faster upon re‐watering. This study has expanded the information available that compares and defines the potential of each species under moisture stress and emphasizes the importance of balancing short‐term DM production with long‐term persistence in choice of pasture species.     

Inheritance of protein content and its correlation with grain yield in pigeonpea (Cajanus cajan (L.) Millsp.)

Four lines of pigeonpea (Cajanus cajan (L.) Millsp.) ware selected for variability in protein content and were used as parents in crosses. The F₂ mean protein contents were generally between the parents, but slightly closer to the low-protein parent. Reciprocal differences in protein of F₁ seeds and its absence in F₂ seeds showed that the maternal genotypes controlled protein content.The broad sense heritability estimates varied from 34 to 62 per cent in different crosses. These low and variable values indicate high environmental-influence on protein content and relatively low additive genetic variance. A minimum of 3 or 4 genes control protein content. Low protein was partially dominant over high protein.Grain yield and protein content were negatively correlated in F₂ plants from crosses between low and high protein lines. Grain yield and protein yield were highly correlated. It is suggested that for total protein production per unit area efforts should be directed towards increased seed yield while maintaining per cent protein near average levels rather than by selecting for high protein in the grains alone.

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Zusammenfassung Vier Linien der Strauch- oder Taubenerbse (Cajanus Cajan (L.) Milsp.) wurden auf Variabilität des Eiweißgehalts ausgelesen und als Eltern für Kreuzungen benutzt. Die F₂-Generation mit mittleren Eiweißgehalten lag im allgemeinen zwischen den Eltern aber doch etwas näher an den Eltern mit niedrigen Eiweißgehalten. Reziproke Verschiedenheiten im Eiweiß der F₁-Samenkörner und seine Abwesenheit im F₂-Samen zeigte, daß der Genotyp der Mutter die Höhe des Eiweißgehalts kontrolliert.Die breitgefächerten Vererbungen zeigen Variationen von 34 zu 62 % bei verschiedenen Kreuzungen. Diese niedrigen und variablen Werte zeigen den großen Einfluß der Umweltfaktoren auf den Eiweißgehalt und relativ wenig additive genetische Varianz. Nur ein Minimum von 3 oder 4 Genen kontrolliert die Höhe des Eiweißgehalts. Niedriger Eiweißgehalt war teilweise dominant über hohen.Samenertrag und Eiweißgehalt waren in F₂-Pflanzen negativ korreliert und zwar bei Kreuzungen zwischen Linien mit niedrigen und hohen Eiweißgehalten. Samenertrag und Eiweißertrag waren hochkorreliert. Es müssen zur Eiweißproduktion je Flächeneinheit Anstrengungen gemacht werden, um höhere Samenerträge zu erzielen, wobei der Eiweißgehalt eher nahe eines mittleren Wertes gehalten werden sollte als durch Selektrion hohe Eiweißgehalte in den Körnern zu gewinnen.

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A part of the All India Co-ordinated Research project for improvement of Pulses, financed by Indian council of Agricultural Research.     

Effect of defoliation management, based on leaf stage, on perennial ryegrass (Lolium perenne L.), prairie grass (Bromus willdenowii Kunth.) and cocksfoot (Dactylis glomerata L.) under dryland conditions. 2. Nutritive value

A field experiment was undertaken between April 2003 and May 2004 in southern Tasmania, Australia, to quantify and compare changes in the nutritive value of perennial ryegrass (Lolium perenne L.), prairie grass (Bromus willdenowii Kunth.) and cocksfoot (Dactylis glomerata L.) under a defoliation regime based on stage of leaf regrowth. Defoliation interval was based on the time taken for two, three or four leaves per tiller to fully expand. At every defoliation event, samples were collected and analysed for acid‐detergent fibre (ADF), neutral‐detergent fibre (NDF) and total nitrogen (N) concentrations and to estimate metabolizable energy (ME) and digestible dry matter (DDM) concentrations. Amounts of crude protein (CP) and metabolizable energy (MJ) per hectare values were subsequently calculated. There was a significantly lower (P < 0·001) NDF concentration for perennial ryegrass compared with prairie grass and cocksfoot, and a significantly lower (P < 0·001) ADF concentration for cocksfoot compared with prairie grass and perennial ryegrass, regardless of defoliation interval. The CP concentration of cocksfoot was significantly greater (P < 0·001) compared with the CP concentrations of prairie grass and perennial ryegrass. The estimated ME concentrations in cocksfoot were high enough to satisfy the requirements of a lactating dairy cow, with defoliation at or before the four‐leaf stage maintaining ME concentrations between 10·7 and 10·9 MJ kg^?1 DM, and minimizing reproductive plant development. The ME concentrations of prairie grass (10·2–10·4 MJ kg^?1 DM) were significantly lower (P < 0·001) than for cocksfoot (as above) and perennial ryegrass (11·4–11·6 MJ kg^?1 DM) but a higher DM production per hectare resulted in prairie grass providing the greatest amounts of ME ha^?1.     

Inheritance of tolerance ofGlobodera pallida and the relationship between tolerance and resistance toG. pallida in potatoes

Summary The tolerance of and resistance toGlobodera pallida of two potato progenies which segregated for these characteristics were assessed in pots in the glasshouse. The level of tolerance varied widely between genotypes within the progenies, with several genotypes being significantly more tolerant than the intolerant parent. The levels of resistance and tolerance in the progenies were not significantly correlated. No indications were obtained that the ranking of genotypes for tolerance is influenced by the density ofG. pallida in the soil. The results confirm that selection for tolerance in aG. pallida resistance breeding programme is useful and feasible.     

Nutrient composition and anti-nutritional factors in selected vegetable soybean (Glycine Max [L.] Merr.)

The genetic variation in the nutrient composition and anti-nutritional factors of 17 vegetable soybean genotypes were determined and a wide variation in protein %, total phosphorus (TP_i) and available phosphorus (AP) was found among these genotypes. Variations in Ca, K, Fe, Mn, and Cu were also documented. Variation was also found for trypsin inhibitor (TI) activity and Phytate (PA) content. A highly significant and negative correlation (r=–0.533,P<0.01) was observed between TI and total protein. Strong positive correlation (r=0.90) was also found between TP_i and AP. Several genotypes (Sooty, Emperor, Wilson-5, PI 416771, PI 417322) showed good nutritional potential and can be used in the breeding program. High protein %, TP_i, and minerals are desirable qualities for vegetable-type soybeans that make it as food with high nutrient density. Studies on the nutritional evaluation of immature vegetable type soybean seeds at different reproductive stages are also underway.Agricultural Research Station Journal Article Series No. 172. The use of any trade name varieties, and/or vendors does not imply the exclusion of other products or vendors that may also be suitable.     

Multivariate analysis of relationship between potato (Solanum tuberosum L.) yield,amount of applied elements,their concentrations in tubers and uptake in a long-term fertilizer experiment

The aim of this study was to investigate how potato yield, the concentrations of elements (N, P, K, Ca, Mg, S, As, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) in tubers and their uptake are affected by mineral N, P and K fertilizers, straw and pig slurry application.     

Dynamical partition of photosynthates in tillers of rice (Oryza sativa L.) during late growth period and its correlation with feeding value of rice straw at harvest

This study was to investigate the dynamical partition of photosynthates in panicle-removed tillers of rice (Oryza sativa L.) during late growth period and its correlation with the feeding value of rice straw at harvest. Four rice cultivars (Liangyou 108, Huaidao 6, Nanjing 43, Nanjing 44) were cultivated in Nanjing under the same management of Jiangsu area, and were sampled from weeks 1 to 5 after anthesis and at harvest in 2008, 2009 and 2010. Then, the content of nonstructural carbohydrates (NSC), hemicellulose, and acid detergent fiber (exclusive of residual ash, ADFom) in tillers were determined. The crude protein (CP) content in tillers at harvest was assayed in 2009 and 2010. Freehand sections of the fourth internode of main culm were made to visualize the starch particles in parenchyma cells in week 1, 3 and 5 after anthesis in 2010. The results showed that the content of NSC decreased sharply from week 1 to 3 and then increased to week 5 after anthesis; hemicellulose in week 5 remained at an approximate level with that of week 1; ADFom increased slightly from week 1 to 3, and then stayed constant till week 5 after anthesis. The starch particles in parenchyma cells of stems decreased from week 1 to 3 and increased slightly till week 5 after anthesis again. The rebounding rate of NSC (NSCRR) was positively correlated with the content of NSC and CP at harvest while negatively correlated with the content of hemicellulose and ADFom at harvest.     

Study of gene effects for cotton yield and Verticillium wilt tolerance in cotton plant (Gossypium hirsutum L.)

Verticillium wilt (VW), caused by Verticillium dahliae Kleb., is a destructive disease of cotton (Gossypium hirsutum L.). The use of resistant cultivars has long been considered the most practical and effective mean of control. The aim of this work was to study the quantitative genetic basis of Verticillium wilt resistance in Upland cotton by using five genotypes and their possible crosses without reciprocals selecting simultaneously for resistance and desirable agronomic characteristics. Five cotton cultivars and 10 F1s from half-diallel crosses were analyzed for VW resistance. The seed cotton yield, the number of bolls/ plant, and boll weight were measured and Verticillium wilt index (VWI) was estimated during two crop seasons in two different sites each year always on plots with naturally infested soil. Genetic components of variance were analyzed using the Hayman model. Analysis of variance for all characters showed significant differences between genotypes, without genotype-site interaction in most cases. Both, additive genetic variance component (D) and dominance genetic variance components (H1 and H2) were presented in all characters, except for VWI. D was the most important component for boll weight and VWI. Boll weight was the most correlated character with seed cotton yield and VWI. Broad sense heritability was high for boll weight and VWI, moderate for seed cotton yield and low for bolls per plant. Narrow sense heritability was moderate for boll weight, and high for VWI.     

Effects of heat on the removal of polyphenols and in vitro protein digestibility of cowpea (Vigna unguiculata (L.) Walp.)

Simple wet heat treatments like simple boiling (atmospheric pressure, 100 °C) and pressurized boiling (higher than 100 °C) reduced the polyphenol content of mature dark red seeds of cowpea (Vigna unguiculata (L.) Walp.) cultivar UPL Cp 3 by 61 to 80% and improved in vitro protein digestibility (IVPD) by 6 to 26%. Pressurized steaming (higher than 100 °C) removed 48 to 83% of the polyphenols but increased IVPD by only 1.1 to 4.2%. Dry heat as exemplified by roasting and microwave treatment inactivated 58 to 71% of the tannins but increased IVPD by only 1%. All the heat treatments were effective in removing/inactivating polyphenols though different responses were observed with the resulting in vitro protein digestibilities.     

水稻(Oryza sativa L.)正常和无花粉花药绒毡层解体过程孢粉素行为的比较观察(英文)

 利用派罗宁B-黄色组分诱导孢粉素产生荧光的特异性,观察了水稻M 101品种以及它的无花粉型胞核雄性不育(GMS)突变体Ⅰ-15系花药绒毡层解体过程中孢粉素的行为。M-101品种花药绒毡层的解体过程大体可分为两个阶段:在小孢子发育期,绒毡层主要分泌孢粉素;在花粉发育期,绒毡层主要降解非孢粉素物质。Ⅰ-15系花药绒毡层的解体过程虽然出现了一系列异常现象,但绒毡层解体的起始时间和阶段顺序性与M-101品种相似。对绒毡层解体过程孢粉素行为的有关事态及其与花粉发育的关系等问题进行了讨论。     

油菜用地养地的作物优势及其在冬闲田开发中的应用潜力

油菜是我国种植面积最大的油料作物,是国产食用植物油的重要来源。油菜生长过程可以优化土壤结构、增加土壤养分、培肥土壤地力,具有用地养地的特征优势。同时,因其具有较强的环境适应能力,可作为先锋作物改良障碍土壤。然而,近年来由于劳动力不足、种植效益低、农民种植积极性不高等因素,导致冬闲田面积逐年增加,冬季光温水土自然资源未能得到有效利用。而油菜作为冬季种植的油料作物,不与粮争地,是开发利用冬闲田最有潜力的作物。利用冬闲田发展油菜生产,不仅可以提升油料产量,还可以充分发挥其养地优势提高后茬作物产量品质、增加种植收益,对维护我国食用油供给安全、助力粮油兼丰及农业绿色可持续发展具有重要意义。本文结合我国油菜生产现状,针对南方稻区冬闲田油菜轮作的生产发展需要,综述了油菜用地养地（油用或肥用）的作物优势,旨在为因地制宜利用南方冬闲田发展油菜生产助力油料产能提升提供科学依据。     

辣椒基因组中XTH基因家族的鉴定与表达特征分析

为全面了解木葡聚糖内转糖苷酶/水解酶(xyloglucan endotransglucosylase/hydrolase,XTH)基因在辣椒基因组中的特征,利用生物信息学方法鉴定出了所有辣椒XTH基因家族成员,并对基因的结构、染色体定位、系统进化关系和保守结构域等进行了预测,同时基于转录组数据集分析了XTH基因在辣椒不同器官、不同发育时期果实中的表达特征。结果表明,辣椒XTH家族包含23个基因成员,不均衡分布在除10号染色体外的其余11条染色体上;23个基因包含1~5个不等的内含子;系统进化分析表明,辣椒XTH蛋白可分为3个亚家族;基因表达特征分析显示,大多数辣椒XTH的表达具有组织特异性,CaXTH2、CaXTH21、CaXTH13和CaXTH23极有可能与辣椒果实的膨大与成熟相关。本研究为深入了解辣椒XTH基因的功能奠定了基础。     

The nitrogen response of potato (Solanum tuberosum L.) in the field: nitrogen uptake and yield, harvest index and nitrogen concentration

Summary The response of potato to different rates of nitrogen supply ranging from 0–40 g m⁻² N was studied in five field experiments near Wageningen. NL (52⁰ North). In total two late potato cultivars and two sites were used during successive seasons. The results are summarized in a set of regression equations separately for total crop and tubers. The relation between nitrogen taken up (g m⁻²) in the total crop and total dry matter production (g m⁻²) could be described with the exponential equation: 1942–1900 * 0.93^X (r²=0.953, n=62). Nitrogen concentrations in the dry matter increased linearly with nitrogen uptake. Harvest indices for dry matter and nitrogen tended to decline with increase in N uptake. Cultivars differed only in the effect on N on tuber dry matter concentration. The relation between nitrogen uptake and nitrogen supply could be fitted with quadratic regression models. but coefficients were influenced by site and season.