杂交籼稻与其亲本低温障碍耐冷差异的相关性分析

在较高海拔地区采用分期播种的自然低温胁迫方法，以平均结实率和相对冷敏指数（CRI）为指标，对以3个不育系与5个恢复系组配的15个不完全双列杂交籼稻组合的障碍型耐冷性进行了初步研究。结果表明：（1）自然低温胁迫下，相同恢复系与不同不育系、相同不育系与不同恢复系组配系列杂交组合间平均结实率和CRI值的差异达到极显著水平，且耐冷性前者呈A／R5〉A／R3〉A／R2〉A／R1〉A／R4，后者呈A3／R〉A1／R〉A2／R的趋势，表明杂交籼稻障碍型耐冷性的表达既与恢复系有关又受不育系的影响；（2）杂交组合不同播期之间的低温平均结实率和CRI值存在显著或极显著的正相关。其中，低温平均结实率的相关系数在Ⅳ期与Ⅲ、Ⅱ期之间分别为0．6030^＊和0．6620^＊，在Ⅲ期与Ⅱ期之间为0．5641^＊；而CRI值的相关系数在Ⅳ期与Ⅲ、Ⅱ期间分别为0．7439^＊和0．9770^＊，在Ⅱ期与Ⅲ期之间为0．7267^＊。     

旱稻277夏直播高产栽培技术

旱稻 277系中国农业大学选育的旱稻新品种,临沂市 1998年引进种植,表现了良好的耐旱和丰产特性. 2000- 2003年连续 4年进行高产栽培技术开发,取得了良好的社会经济效益.     

A sequential approach for improving AZODYN crop model under conventional and low-input conditions

Advances in scientific understanding of the plant and soil behaviour in a cultivated field led to the design of numerous soil–crop models simulating crop growth. The frequent low predictive quality of these models is linked to uncertainties in inputs, parameters and equations. The AZODYN crop model predicting wheat grain yield and grain protein content was previously developed to support decision for N management of conventional and organic wheat crops. This paper outlines a sequential approach to improve the predictions of the AZODYN model by testing various formalisms. This study is based on the comparison of 38 versions of the model assessed in multi-environment trials carried out under conventional or low-input conditions. This paper describes and discusses the methodology. The results show that the predictive value of grain yield and grain protein content could be largely improved without increasing model complexity.     

A sequential approach for improving AZODYN crop model under conventional and low-input conditions

Advances in scientific understanding of the plant and soil behaviour in a cultivated field led to the design of numerous soil–crop models simulating crop growth. The frequent low predictive quality of these models is linked to uncertainties in inputs, parameters and equations. The AZODYN crop model predicting wheat grain yield and grain protein content was previously developed to support decision for N management of conventional and organic wheat crops. This paper outlines a sequential approach to improve the predictions of the AZODYN model by testing various formalisms. This study is based on the comparison of 38 versions of the model assessed in multi-environment trials carried out under conventional or low-input conditions. This paper describes and discusses the methodology. The results show that the predictive value of grain yield and grain protein content could be largely improved without increasing model complexity.     

对北方旱地覆膜玉米高产栽培最佳播期的研究

最佳播期，是北方旱地覆膜玉米高产栽培中关键技术措施之一。通过对北方干旱、半干旱生态类型区自然资源的分析，提出了综合应用地膜的增温、保墒效应，对覆膜玉米适时早播的理论基础和生产实践进行了分析研究，进一步明确了适时早播的标准。     

Attributes of wheat cultivars for late autumn sowing in genes expression and field estimates

Due to the growing interest in Central and Eastern Europe on cropping of wheat in optional late autumn terms, called facultative, genetic research and field evaluation were taken on four spring cultivars: Tybalt (NL), Monsun (DE), Ostka Smolicka (PL) and Bombona (PL), currently being recommended by breeders. The PPD gene analyze, expression level of dehydrine genes (WCS120 and WDHN13) in cooling test, and qPCR for RNA isolation and analyses of WCS120 and WDHN13 gene expression at the BBCH12 stage of wheat were estimated. Molecular analysis of PPD-D1 gene confirmed the presence of photoperiod sensitive allele ppd-D1b in all tested genotypes. The highest level of NRE WCS120 gene was detected in cultivars Tybalt and Bombona. Two-year field experimental study assessed the growth, development and productivity of facultative and spring crops of studied cultivars. Based on our results from field experiments and result of molecular analysis of alleles of PPD-D1 gene, the tested genotypes can be considered as potentially facultative genotypes.     

Genome-wide association study for frost tolerance in rapeseed/canola (Brassica napus) under simulating freezing conditions

Rapeseed/canola seedlings can be easily damaged by spring frost, which can rupture the cells and kill the plant. Genetic variations for frost tolerance have known to exist within rapeseed/canola gene pool. A genome-wide association study (GWAS) was conducted using 231 diverged rapeseed/canola germplasm to find the significant markers of the freezing tolerance traits. The genotypes were obtained from 21 countries and comprised of spring, winter and semi-winter growth types. The genotypes were evaluated in plant growth chamber under simulated freezing conditions. Highly significant genotypic variation was observed for the freezing tolerance. The best three freezing tolerant germplasms (Rubin, KSU-10, and AR91004) were winter type, while the four most freezing susceptible germplasms (Polo Canada, Prota, Drakkar, and BO-63) were all spring type. No geographical or growth habit type clusters were identified by structure analysis in this mixed population. One QTL was identified that was located on chromosome A02. Six freezing/abiotic stress tolerance genes have been identified in this study.     

不同生态条件下播期对机插杂交籼稻日产量的影响

为探讨不同生态条件下播期对机插杂交籼稻日产量的影响,并提出相应的丰产对策,以3个杂交籼稻品种宜香优2115、F优498和川优6203为材料,采取毯苗机插栽培方式,在四川的南部、射洪、安州和大邑4个生态点,通过分期播种,研究不同生态条件下播期对机插杂交籼稻全生育期、产量和日产量的影响。结果表明,不同生态条件下机插杂交籼稻的全生育期、产量和日产量存在差异;随着播期从3月下旬推迟至5月上旬,机插杂交籼稻播种至拔节期天数缩短,抽穗至成熟期天数增加,平均全生育期从159.5 d逐渐缩短至150.7 d,平均产量从10,260.45 kg hm^–2逐渐下降至7795.83 kg hm^–2,平均日产量从64.58 kg hm^–2 d^–1逐渐下降至51.95 kg hm^–2 d^–1。气象因子对机插杂交籼稻产量和日产量的影响在不同生态条件下存在差异,产量与全生育期平均气温日较差、日照时数呈显著正相关,与水稻全生育期日平均温度、平均日最低温度、日平均相对湿度和降雨量呈显著负相...     

Comprehensive assessment of nutrient management technologies for cauliflower production under subtropical conditions

We developed a methodological protocol for comprehensive evaluation of nutrient management (NM) technologies for production of cauliflower taking its yield, quality, profitability, energy balance and environmental sustainability in terms of soil quality as the goal variables. Fifteen NM technologies comprising three sources of nutrients viz., organics [farmyard manure (FYM), vermicompost (VC) and green manure], inorganic fertilizations (recommended NPK at the rate of 200-44-82 kg ha⁻¹and 125% of recommended NPK) and their selected combinations were tested for producing cauliflower for six consecutive growing seasons during 2006–2011. Integrated NM technology proved to be economically sound and environment-friendly practice. It helped to produce better quality cauliflower with higher value added products such as crude protein, dietary fibre, and vitamin C. Further, it concomitantly maintained better soil quality by improving soil organic carbon stock, microbial biomass carbon, bulk density and extractable plant available nutrients. Combining all the parameters together by employing non-parametric evaluation of regression factor scores through principal component analysis, the NM technology of FYM 5 Mg ha⁻¹ + 125% of recommended NPK and VC 3 Mg ha⁻¹ + 125% of recommended NPK were found to be the best among the NM technologies compared. The superiority of the technologies were attributed to higher curd biomass yield (8.36 and 9.70 Mg ha⁻¹, respectively), higher economic return (benefit-cost ratio 2.7 and 2.5; marginal rate of return 8.0 and 5.1, respectively), more energy conserving efficiency (net energy 22.4 and 25.7 GJ ha⁻¹; output-input energy ratio 1.86 and 2.00, respectively) and greater improvement in the indices of soil quality (6.219 and 5.709, respectively) and crop quality for human (6.7 and 7.4, respectively) and animal (7.4 and 6.4, respectively) nutrition. Organics were less productive, less profitable, and energetically less efficientas compared to integrated and inorganic systems for cauliflower production in subtropics.     

Risks of yield loss due to variation in optimum density for different maize genotypes under variable environmental conditions

Understanding the nature of complex genotype‐by‐environment‐by‐management interactions is crucial to identify risks and opportunities for increasing maize yield and profitability in rainfed production systems. The objectives of this study were to (i) define the conditions where hybrids of different maturity and plant densities are viable options in terms of improving productivity, and (ii) quantify the risk levels associated with different genotype‐by‐management combinations in relation to target environments. Responses to plant density were analysed on field experimentation with different genotypes representing early, medium and late maturity types and 2, 4 and 6 plant/m² plant densities at three major or potential dryland maize production environments in Queensland, Australia. Agricultural Production Systems sIMulator (APSIM)‐Maize module was employed to simulate yield responses and compute the cumulative probability distribution. APSIM simulations suggested that the risk of expecting a yield level less than 2 t/ha increased up to about 17 and 27% for quick and late maturing types, respectively, when density increased to 10 plants/m² in marginal environments such as Emerald. In relatively better environments, however the risk increased only up to 10% for late hybrids, and 7% for a quick hybrid at 10 plants/m². In both high and low potential environments, choice of hybrids and plant densities should be based on seasonal weather forecasts to minimize risks and maximize opportunities for higher yields.     

Genetics of grains per spike in durum wheat under normal and late planting conditions

Parental, F₁, F₂, BC₁, BC₂, BC₁₁, BC₁₂, BC₂₁, BC₂₂, BC₁ self and BC₂ selfed generations of three crosses involving six cultivars of durum wheat (Triticum durum Desf.) were studied for grains per spike under normal and late sown environments to analyze the nature of gene effects. A 10-parameter model did not fully account for the differences among the generation means. In two cases more complex interactions or linkage were involved in the inheritance of grains per spike in durum. Both digenic and trigenic epistatic interactions had a role in controlling the inheritance of grains per spike, however, trigenic interactions contributed more than digenic interactions. Non-fixable gene effects were many times higher than fixable ones in all three crosses and in both sowing environments indicating a major role of non-additive gene effects in the inheritance of this trait. Duplicate epistasis between sets of three genes under both environments was recorded for the cross Raj 911 × DWL 5002. Epistatic interactions, particularly the trigenic ones, contributed the maximum significant heterosis. Epistatic interactions involving dominance in the F₂ generations caused significant inbreeding depression. Selective diallel mating and/or biparental mating could be used for amelioration of grains per spike in durum wheat.     

QTL for yield, yield components and canopy temperature depression in wheat under late sown field conditions

A wheat (Triticum aestivum L.) recombinant inbred line (RIL) population was used to identify quantitative trait loci (QTL) associated with yield, yield components, and canopy temperature depression (CTD) under field conditions. The RIL population, consisting of 118 lines derived from a cross between the stress tolerant cultivar ‘Halberd’ and heat stress sensitive cultivar ‘Karl92’, was grown under optimal and late sown conditions to impose heat stress. Yield and yield components including biomass, spikes m^?2, thousand kernel weight, kernel weight and kernel number per spike, as well as single kernel characteristics were determined. In addition, CTD was measured during both moderate (32–33 °C) and extreme heat stress (36–37 °C) during grain-filling. Yield traits showed moderate to high heritability across environments with a large percentage of the variance explained by genetic effects. Composite interval mapping detected 25 stable QTL for the 15 traits measured, with the amount of phenotypic variation explained by individual QTL ranging from 3.5 to 27.1 %. Two QTL for both yield and CTD were co-localized on chromosomes 3BL and 5DL and were independent of phenological QTL. At both loci, the allele from Halberd was associated with both higher yield and a cooler crop canopy. The QTL on 3BL was also pleiotropic for biomass, spikes m^?2, and heat susceptibility index. This region as well as other QTL identified in this study may serve as potential targets for fine mapping and marker assisted selection for improving yield potential and stress adaptation of wheat.     

Yield, biomass and yield components in dwarf, semi-dwarf and tall isogenic lines of spring wheat under recommended and late sowing dates

Grain yield and some of its physiological determinants were analysed in a field study conducted over two growing seasons with standard-height (SH), semi-dwarf (SD) and dwarf (DD) isogenic lines of a spring wheat sown at recommended and delayed dates. The objective was to test whether the action of Rht1 and Rht2 alleles in improving grain yield depended upon sowing date. As expected, the dwarfing genes significantly reduced plant height in both sowings and growing seasons. There was a tendency for the SD line to produce more biomass than the SH and DD lines, although the differences were mostly not significant. Harvest index was linearly and negatively related to plant height. Consequently, the SD and SH line showed the highest and lowest grain yields in all environments. The optimum height for grain yield was estimated to be c. 70 cm, and this value was not affected by sowing date. Lines carrying Rht1 and/or Rht2 alleles always showed more grains/m² (owing to an increased number of grains per spike and spikes/m²) than the SH line. Conversely, average grain weight was negatively associated with the number of grains/m². Because the slope of this negative relationship was smaller (less negative) than that representing complete compensation, the relationship between grain yield and number of grains/m² was hyperbolic. Although these relationships are frequently regarded as a reflection of increased competition among grains when the number of grains/m² is increased owing to the use of semi-dwarf genes, two alternative hypotheses are analysed and discussed.     

Nitrogen uptake and utilization efficiency of European maize hybrids developed under conditions of low and high nitrogen input

Maize varieties with improved nitrogen(N)‐use efficiency under low soil N conditions can contribute to sustainable agriculture. Tests were carried to see whether selection of European elite lines at low and high N supply would result in hybrids with differential adaptation to these contrasting N conditions. The objective was to analyze whether genotypic differences in N uptake and N‐utilization efficiency existed in this material and to what extent these factors contributed to adaptation to low N supply. Twenty‐four hybrids developed at low N supply (L × L) were compared with 25 hybrids developed at high N supply (H × H). The N uptake was determined as total above‐ground N in whole plants, and N‐utilization efficiency as the ratio between grain yield and N uptake in yield trials at four locations and at three N levels each. Highly significant variations as a result of hybrids and hybrids × N‐level interaction were observed for grain yield as well as for N uptake and N‐utilization efficiency in both hybrid types. Average yields of the L × L hybrids were higher than those of the H × H hybrids by 11.5% at low N supply and 5.4% at medium N level. There was no significant yield difference between the two hybrid types at high N supply. The L × L hybrids showed significantly higher N uptake at the low (12%) and medium (6%) N levels than the H × H hybrids. In contrast, no differences in N‐utilization efficiency were observed between the hybrid types. These results indicate that adaptation of hybrids from European elite breeding material to conditions with reduced nitrogen input was possible and was mainly the result of an increase in N‐uptake efficiency.     

Cytogenetic analysis of two interspecific Citrus allotetraploid somatic hybrids and their diploid fusion parents

Microsporogenesis of two interspecific allotetraploid somatic hybrids, i.e.‘Hamlin’ sweet orange +‘Rough Lemon’ (HR) and ‘Key’ lime +‘Valencia’ sweet orange (KV), was examined and compared with their corresponding diploid fusion parents. Meiotic analysis revealed that only 13.2 and 18.0% of the meiocytes exhibited normal tetrad formation in HR and KV somatic hybrid plants, respectively, and irregular chromosome behaviour with univalent or multivalent pairing occurred. Moreover, meiotic abnormalities such as chromosome bridges, chromosomes orientated away from the equatorial plate, especially lagging chromosomes, which resulted in different sizes of pollen grain, were frequently observed in both somatic hybrids. As expected, the percentage of chromosome abnormalities was much lower in their corresponding diploid fusion parents. HR and KV had 15.4 and 7.2% pollen germinability, respectively, intermediate between their corresponding fusion parents. The meiotic behaviour of these somatic hybrids provided valuable information for their practical utilization in a citrus breeding programme.     

Genetic and genomic approaches for improving biofuel production from maize

Grasses, which are currently at the basis of cattle feeding, will, in the near future, be a major source of cell wall carbohydrates for sustainable biofuel production. The association of lignins with other matrix components, together with linkages between cell wall carbohydrates, greatly influences cell wall properties, including the degradability of structural polysaccharides by micro-organisms in animal rumen or industrial fermenters. The improvement in biofuel production from plants is based on the understanding of the cell wall composition and assembly, and on the discovery of genetic and genomic mechanisms involved in each component biosynthesis and their depositions in each lignified tissue. While nearly 40 QTL have been shown for lignin content, only seven locations appeared of greater importance in investigated genetic resources. Expression studies highlighted that several genes in the lignin pathway are less expressed in lines with higher cell wall degradability. However, only a few lignin pathway genes mapped in QTL positions, and the fully relevant candidates might be genes involved in regulation of lignin pathway genes, or in regulation of lignified tissue assembly.     

Early generation selection for potato tuber quality in progenies of late blight resistant parents

Developing disease resistant cultivars is one of the major objectives for a potato (Solanum tuberosum L.) breeding program, but many resistant clones have not achieved commercial acceptance because of late maturity and non-marketable tuber characteristics. Selection for tuber quality should have greater emphasis inbreeding disease resistant cultivars. The objectives of this study were 1) to evaluate the ability of late blight (Phytophthora infestans (Mont.) de Bary) resistant parents to transmit chip-processing (tuber appearance, specificgravity, and chip-color) or tablestock (tuber appearance) quality to the offspring and 2) to compare selecting for tuber quality in single-hill versus eight-hill generations. We made crosses among eight unadapted potato cultivars (B0718-3,Bertita, Bzura, Greta, Libertas, Stobrawa, Tollocan, and Zarevo) with reported late blight resistance with adapted susceptible cultivars/breeding clones to generate 95populations (4,750 seedlings). Approximately 10% of the progeny from each cross were selected from single-hill plots based on tuber appearance, number, shape, and internal defects. These selected clones (408) were evaluated for tuber appearance, specific gravity, and chip-color. The same evaluations in the following year were made on tuber samples from eight-hill plots. Libertas and Tollocan were the best parents for transmitting chip-color; B0718-3, Zarevo, and Tollocan for transmitting tuber appearance; and Bzura, Libertas, and Zarevo for transmitting high specific gravity to the highest percentage of the offspring. Overall, 50% and 56% of the clones based on single- and eight-hill generation, respectively, were considered to possess chip-processing quality; over 90% of the clones had acceptable tablestock quality. A total of 71% of the clones possessing acceptable chip-processing and 95% of the clones possessing acceptable tablestock quality selected in both generations were identified in single-hill plots. The evaluation of tuber quality characteristics in single-hill generation not only permitted the identification of clones with acceptable chip-processing and tablestock, but also increased the amount of clonal information for the following generation of selection. In crosses between late blight resistant and susceptible clones, selection for tuber quality traits can be initiated in single-hill generation using a moderate selection intensity and precede late blight testing. This revised version was published online in August 2006 with corrections to the Cover Date.     

Genetics of yield, quality and shelf life characteristics in tomato under normal and late planting conditions

Seventy nine genotypes of tomato (15 lines, four testers and their 60 F₁ hybrids produced in line × tester fashion) were evaluated under normal (E₁) and late planting (E₂) conditions in the Department of Vegetable Crops, Punjab Agricultural University, Ludhiana, India, to determine the nature of gene action controlling yield, quality and shelf life characteristics and to identify a few good combiner genotypes which may be used in further breeding programmes to extend the fruit availability period of tomato in North Indian plains. The lines were significantly different from testers for most of the characters thereby justifying the choice of testers. Additive gene action was predominant for days to ripening, total yield per plant, marketable yield per plant, number of fruits per plant, average fruit weight, fruit shape index and lycopene in both the environments, whereas non-additive genetic variance predominated in controlling firmness index, number of locules, pericarp thickness, alcohol insoluble solids (AIS), dry matter, total soluble solids (TSS), titratable acidity, TSS:Acid ratio, pH, ascorbic acid and shelf life, under both normal and late planting conditions. The best general combining ability (gca) effects, among females, in respect of yield per plant were shown by Spectrum in E₁ and by LT-42 in E₂. Among the testers, the best gca values in both the environments were possessed by nor-RM-1 for total yield per plant, marketable yield per plant, number of fruits per plant, dry matter and TSS; by rin-RM-2 for firmness index, pericarp thickness and alcohol insoluble solids; by alc-IIHR-2050 for average fruit weight, number of locules and shelf life and by alc-IIHR-2052 for lycopene. The gca of ripening mutants had a nice consonance with their per se performance for most of the characters indicating that additive gene action was operative in these mutants for majority of the traits.