Pod and seed numbers as a function of photothermal quotient during the seed set period of field pea (Pisum sativum) crops

The effects of radiation and temperature during the seed set period (SSP) on pod number per square metre (PN m⁻²) and seed number per square metre (SN m⁻²) and those of temperature during grain filling on unit seed weight (USW, milligram per seed) of field pea (Pisum sativum L.) were examined in experiments involving irrigated crops of three or more cultivars of contrasting maturity sown on two or more dates per year from 1996 to 1998 at Buenos Aires, Argentina. The duration of the seed-setting phase was estimated from records of the progress of flowering on the main stem and an estimate (obtained using an optimisation procedure) of the thermal time from flowering at which the uppermost reproductive node reached the final stage of seed abortion (FSSA). The FSSA at a particular node was assumed to be achieved 200 °C day (T_b=4 °C) after flowering at the same node. The grain-filling phase was assumed to run from the achievement of FSSA at the first reproductive node through to 200 °C day (T_b=0 °C) after the date of achievement of the FSSA by the second flowering node.The treatments (cultivar, sowing date, year) produced important ranges of above-ground biomass (AGB) at maturity (271–782 g m⁻²), seed yield (SY, 119–331 g m⁻²), SN (1062–3698 seeds m⁻²) and USW (67–150 mg seed⁻¹). Seed yield was strongly correlated with SN, and there was full compensation between SN and USW in large-seeded cultivars in the high SN range, but not at lower values of SN or in small-seeded cultivars. Both PN (r=0.83) and SN (r=0.87, P<0.0005) were strongly correlated with the mean daily value of the photothermal quotient (PQ=incident radiation/(mean temperature − base temperature)) for the seed-setting phase. Large- and small-seeded cultivars had PN/PQ and SN/PQ relationships with slopes which did not differ among categories but with significantly different intercepts. When the effects of low temperatures during flowering and early grain growth were allowed for, outliers on the PN/PQ and SN/PQ relationships for unstressed crops fell within the confidence limits of the respective linear regressions. Unit seed weight showed a negative response to mean temperature during the grain-filling phase in large- and small-seeded cultivars. We conclude that the relationships established in these experiments, taken together with previous work by other authors, constitute a robust basis for modelling the yield of unstressed field pea crops.     

Yield components,harvest index and plant type in relation to yield differences in field pea genotypes

Summary The effectiveness of yield components, harvest index and morphological characteristics as selection criteria among four field pea (Pisum sativum L.) genotypes was examined. Genotypes were grown at a wide range of plant populations (9 to 400 plants m^-2) to maximise environmental diversity.Both biological and seed yields approximately doubled from 9 to 100 plants m^-2. This response flattened from 100 to 400 plants m^-2. Differences among the genotypes were found only at 225 and 400 plants m^-2. Analysis of the yield components highlighted the plasticity and large genotype by environment interactions of field peas. The numbers of pods per plant and peas per pod were maximised when each genotype was grown as spaced plants, but the low plant numbers meant seed yields per unit area were at their lowest.Genotypic differences for plant harvest index (PHI) were also only found at 225 and 400 plants m^-2. Broad sense heritability estimates indicated that direct selection for PHI was not feasible. The inference from the yield component and PHI results was that alternative selection criteria such as physiological or morphological characteristics may be necessary for improved yield potential. Classification of each genotype indicated that low seedling vigour may be a positive attribute for crop plants of semi-leafless and conventionally leafed field peas. Selection based on any single plant attribute is unlikely to lead to dramatic improvements in the yield potential of field peas. Selection should be based on plant characteristics rather than on differences in yield components.     

Sources of variation for sustainable field pea breeding

The pea crop (Pisum sativum L.) is a convenient source of plant protein for animal feeding. The objective of this research was to evaluate field pea breeding lines for agronomic performance and seed quality focussed to their use in a sustainable production. Thirty-five field pea breeding lines and six elite cultivars were evaluated for their agronomic value in field in Spain upon 20 traits related to flower, cycle, plant architecture, productivity and seed quality. The lines showed significant differences in all the quantitative traits evaluated and three of them, namely MB-0307, MB-0308, and MB-0319 were chosen to be evaluated, together with the advanced cultivar ZP-1233, in field and in growing chamber for agronomic performance, seed quality and ability for sustainable production. The four accessions displayed high seed protein content that had significant effect of cropping density with averages of 253.6 g kg⁻¹ under low cropping density of 60 plants m⁻² and 259.1 g kg⁻¹ under high cropping density of 90 plants m⁻², therefore, the low cropping density should be regarded as the most convenient. Average yield of the lines MB-0307, MB-0308 and MB-0319 and the cultivar ZP-1233 was fair (197.5 g m⁻²), probably due to the absence of fertilizers and irrigation, aiming for the sustainability of the crop. Intercropping with rye and herbicide application resulted in no differences on the seed yield; therefore, the ability of the breeding lines to grow without herbicide seems to be demonstrated, while the germination of the seeds at low temperature was very good. These results indicate that field pea could be a new protein crop in the North of Spain to satisfy the demand of plant protein for animal feed, based upon adapted breeding lines that combine the ability for growing under sustainable conditions with other desirable agronomic traits maintaining an adequate productivity.     

Harvest index in lentil (Lens culinaris Medik.)

Summary Correlation and path coefficient analyses were conducted to find out the characters associated with grain yield and dry matter production and the ways to improve harvest index in lentil.Correlation studies revealed positive association of harvest index with grain yield but no association with plant dry matter. Grain yield and plant dry matter showed positive correlation with pod number, plant height, and number of primary and secondary branches but negative correlation with 100-seed weight. Generally, the genotypic correlations were in agreement with phenotypic correlations, though the magnitude of the values was higher in the former case. In path analysis, plant height and pod number showed the highest direct effect and, therefore, seem to be the main characters influencing grain yield and plant dry matter. Number of primary and secondary branches, on the other hand, showed negative direct effect on grain yield and plant dry matter. Use of phenotypic or genotypic correlations in path analysis resulted in similar conclusions. It is, therefore, suggested that either phenotypic or genotypic correlations may be used in path analysis with equal efficiency. Based on this study it is suggested to develop tall varieties with good pod bearing but with low number of branches.     

Gene expression profiles of seed coats and biochemical properties of seed coats and cotyledons of two field pea (Pisum sativum) cultivars contrasting in green cotyledon bleaching resistance

Visual quality is one of the major factors determining the market value of field pea (Pisum sativum L.). Breeding for improved visual quality of pea seeds is currently a challenging task, mainly because of the complexity and the lack of sound genetic knowledge of the traits. The objectives of this research were to characterize post-harvest cotyledon bleaching resistance in green pea at the biochemical and gene expression levels. Seed coats and cotyledons of two pea cultivars, CDC Striker (bleaching resistant) and Orb (bleaching susceptible) at three developmental stages [14, 21 and 28 days after flowering (DAF)] and following exposure to accelerated bleaching conditions after harvest (0, 3, 6, and 13 days after bleaching (DAB) were evaluated. CDC Striker had a slower rate of chlorophyll degradation in cotyledons, and a higher total carotenoids to chlorophyll ratio in seed coats, than Orb when seed samples were exposed to high intensity light. An oligo-nucleotide microarray (Ps6kOLI1) revealed that gene expression profiles of the CDC Striker and Orb seed coats were significantly different during seed developmental stages. A significant up regulation of genes involved in the production and accumulation of secondary metabolites responsible for antioxidant properties including epiafzelechin, epicatechin, epigallocatechin, kaempferide, kaempferol 3-O-β-d-sophorotrioside, O-quercetin and rutin, in the seed coats of CDC Striker were observed. Thus, bleaching resistance in field pea could be due to the accumulation of specific carotenoids and phenolic compounds which quench excess light or scavenge free radical singlet oxygen molecules. The candidate genes identified in this project will need to be validated using qPCR to further support their involvement with bleaching resistance before being used for the development of gene specific markers.     

Identification of quantitative trait loci for grain yield, seed protein concentration and maturity in field pea (Pisum sativum L.)

Breeding efforts to improve grain yield, seed protein concentration and early maturity in pea (Pisum sativum L.) have proven to be difficult. The use of molecular markers will improve our understanding of the genetic factors conditioning these traits and is expected to assist in selection of superior genotypes. This study was conducted to identify genetic loci associated with grain yield, seed protein concentration and early maturity in pea. A population of 88 recombinant inbred lines (RILs) that was developed from a cross between 'Carneval' and 'MP1401' was evaluated at 13 environments across the provinces of Alberta, Manitoba and Saskatchewan, Canada in 1998, 1999 and 2000. A linkage map consisting of 193 AFLPs (amplified fragment length polymorphism), 13 RAPDs (random amplified polymorphic DNA) and one STS (sequence tagged site) marker was used to identify putative quantitative trait loci (QTL) for grain yield, seed protein concentration and early maturity. Four QTL were identified each for grain yield and days to maturity, and three QTL were identified for seed protein concentration. A multiple QTL model for each trait showed that these genomic regions accounted for 39%, 45% and 35% of the total phenotypic variation for grain yield, seed protein concentration and days to maturity, respectively. The consistency of these QTL across environments and their potential for marker-assisted selection are discussed in this report.     

Harvest index and evoluation of major food crop cultivars in the tropics

Summary Relative importance of harvest index (I) and total biomass yield (B) to economic yield (Y) was assessed in several food crops at different levels of environmental productivity. Importance of B is generally higher in low than high yielding environments, while that of I is higher in high than low yielding environments. In some crops B is important throughout different yield levels while in others I is important even in low yielding environments.Past efforts by anonymous farmers have consummated a good part of genetic improvement of crop yields through improvement in B. Many venerable land cultivars of grain crops, adapted to unimproved, limited-input cultural conditions, evolved through this process. The same process may not have thoroughly exhausted the yield improvement opportunity through improving I. Success in yield improvement by modern breeding has been limited mainly to high-input cultural conditions characterized by higher soil fertility and irrigation mainly through improvement in I. Varietal improvement possibility for less productive environments is discussed.     

The increase of seed fertility of Brassicoraphanus through cytological irregularity

Summary Amphidiploids (Brassicoraphanus) were produced by means of colchicine treatment of F₁ hybrids between Brassica japonica Sieb. and Raphanus sativus L. The cytology of the amphidiploids was studied from F₁ to F₃ generations. Some plants had the euploid chromosome number 2n=38, whereas others had the aneuploid number 2n=37. One or two of either quadrivalents or trivalents, as well as some univalents, were seen in most of the plants examined. All the plants showed a low seed fertility. In F₃ generation there arose some yellow-flowered plants, all of which showed a higher seed fertility than normal white-flowered plants. It is postulated that the change of flower colour might originate in the segmental exchange of only partially homologous chromosomes following multivalent formation. A gene causing white flower colour was perhaps closely linked to a gene causing sterility, and both genes were probably excluded together through the segmental exchange of the chromosomes. Therefore, it can be said that the increase of fertility was induced by cytological irregularity.     

提高大白菜一代杂种产量的技术措施

大白菜一代杂种是由两个品种的自交系间相互传粉配制而成的.提高种子产量,必须加强苗期和田间管理,这是提高产量的基础.     

Reproductive development response to high daytime temperature in field pea

Flowering plants are highly sensitive to heat stress during reproductive phase, which covers development from floral initiation to seed maturity. The objectives of this study were to diagnose high temperature effects on pollen production and morphology, production of reactive oxygen species (ROS) in pollen grains and ovules in pea cultivar “CDC Golden.” This study also investigated timing and duration of heat exposure at specific developmental stages of floral buds, open flowers and early set pods on flower and pod abortion, seed development and seed yield in “CDC Golden” and a second cultivar “CDC Sage.” The experiments were conducted in growth chambers with two temperature regimes (24/18°C and 35/18°C day/night temperature for 4–14 days) during reproductive development. Heat stress reduced the number of pollen grains per anther, induced smaller pollen grains and increased ROS production in pollen grains, but it did not affect ROS accumulation in ovules and ovule number per ovary. Heat exposure when young floral buds were visible at the first reproductive node was more detrimental to flower retention, seed set, pod development and seed yield compared to heat exposure started later when flowers at the second reproductive node were fully open.     

The effect of temperature during growth and flowering on the seed set of tetraploid freesia

Summary Phytotron experiments have been carried out to study the effect of different temperatures on the seed set of tetraploid freesias during the raising of the plants and at the time of flowering and pollination.The effect of a relatively low temperature during the growth period is reflected in a comperatively greater number of flowers as a result of an increase in number of ramifications of the peduncle. This sometimes promotes the seed yield notwithstanding that the lower temperature reduces the fertility of each seperate flower. It is clearly proved that the temperature during flowering and pollination affects the fertility of the flower and the ultimate seed yield of the plant. Experiments in our phytotron showed 14°C during the growth period and 20°C at the time of pollination to be the optimum combination for a good seed yield.The effect of a lower night temperature was generally favourable, particularly so when measured by the number of seeds per pollinated flower.     

玉米制种纯度低的原因及防止措施

随着农民对种子质量要求越来越高，制种单位往往花费很大的人力、物力，可每年总有一部分种子田纯度不达标，而造成报废。这样既降低了制种户的经济效益，打击了他们的积极性，又影响了制种单位的信誉。根据自己的工作经验，对影响玉米种纯度的因素进行分析，并提出相应的预防措施。１．影响玉米杂交种制种纯度的因素１．１自交系质量不好自交系除了自繁就是调入，自繁有些只是进行简单的重复繁殖、使用，而不进行田间套袋、复壮、提纯，甚至个别自交系连续多年重复使用。加上自交系较多，收获、贮存、保管混乱，容易产生机械混杂，导致自交…     

豌豆种子发育过程中贮藏蛋白质的合成

对豌豆种子发育过程中贮藏蛋白质的生物合成的研究结果表明:豌豆种子发育过程中,干物质累积量、单粒含氮量都随开花后日数增加而增加。其中开花第3天出现LMW蛋白质组分,第6天出现HMW蛋白质组分;第15天出现豌豆球蛋白、第18天出现豆球蛋白,第21天出现伴豌豆球蛋白,第27天各种蛋白质组分累积达最大值。其累积的顺序是:豌豆球蛋白——豆球蛋白—伴豌豆球蛋白。     

Absence of a genetic relationship between salt tolerance during seed germination and vegetative growth in tomato

Two approaches were used to determine the relationship between salt tolerance during seed germination and vegetative growth in tomato. First, F₄ progeny families of a cross between a breeding line, ‘UCT5’ (salt sensitive at all developmental stages), and a primitive cultivar, ‘PI 174263’ (salt tolerant during germination and vegetative growth), were evaluated in separate experiments for salt tolerance during germination and vegetative growth. There were significant differences among the F₄ families in both the rate of seed germination and the plant growth (dry matter production) under salt stress. There was, however, no significant correlation between the ability of seeds to germinate rapidly and the ability of plants to grow under salt stress. In the second approach, selection was made for rapid germination under salt stress in an F₂ population of the same cross and the selected progeny was evaluated for salt tolerance during both germination and vegetative growth. The results indicated that selection for salt tolerance during germination significantly improved germination performance under salt stress; a realized heritability estimate of 0.73 was obtained. Selection for salt tolerance during germination, however, did not affect plant salt tolerance during vegetative growth; there was no significant difference between the selected and unselected progeny based on either absolute or relative growth under salt stress. Obviously, in these genetic materials, salt tolerance during germination and vegetative growth are controlled by different mechanisms. Thus, to develop tomato cultivars with improved salt tolerance, selection protocols that include all critical developmental stages would be desirable.     

水杨酸提高甘草种子萌发和幼苗生长对盐胁迫耐性的效应

The present study investigated the effects of salicylic acid treatments on morphology, physiological and biochemical parameters and their relationship to salt stress of G. uralensis Fisch seeds and seedlings. Under the salt stress of 200 mmol L^-1 NaCl, the application of 0.5 mmol L^-1 salicylic acid on G. uralensis Fisch seeds could significantly promote the elongation of radicle, increase fresh weight of seedlings, reduce the content of malondialdehyde (MDA) and proline in the radicle, and improve the activity of peroxidase (POD). Under the salt stress (i.e. 100 mmol L ^-1 and 200 mmol L^-1 NaCl), the application of 0.5 mmol L^-1 salicylic acid on G. uralensis Fisch seedling could reduce MDA and proline content, and increase the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) in different degrees. Under salt stress condition, the application of salicylic acid could increase the root glycyrrhizinic acid content. In summary, the application of salicylic acid could improve the tolerance to salt stress by alleviating the inhibition of salt stress on the germination of seeds, increasing the activity of antioxidant enzymes, and reducing the degree of membrane lipid peroxidation.     

Total phenolics and condensed tannins in field pea (Pisum sativum L.) and grass pea (Lathyrus sativus L.)

Seed samples of seventeen field pea cultivars grown at five locations, and nine grass pea lines grown at two locations, in western Canada during 1993 and 1994 were analysed for total phenolics and condensed tannins. Each location in each year was considered as one environment. Total phenolics in field pea differed significantly among cultivars, ranging from 162 mg/kg DM (dry matter) (CE, catechin equivalents) for AC Tamor to 325 mg/kg DM (CE) for Richmond. Field pea had barely detectable levels of condensed tannins. Total phenolics in grass pea ranged from 868 mg/kg DM (CE) for L880388 to 2059 mg/kg DM (CE) for LS89110. Condensed tannins in grass pea ranged from 0.89 g/kg DM (CE) for L880388 to 5.18 g/kg DM (CE) for LS89125. Cultivar had a larger relative contribution to total phenolic levels in field pea and to total phenolic and condensed tannin levels in grass pea than environment. Total phenolic and condensed tannin levels were not correlated with seed yield and seed protein content in field pea or grass pea. Levels of total phenolics and condensed tannins were positively correlated in grass pea. Grass pea seeds with darker seed coat colour contained higher levels of condensed tannins. This revised version was published online in July 2006 with corrections to the Cover Date.     

Nutrient seed priming improves seedling development of maize exposed to low root zone temperatures during early growth

Low root zone temperature (RZT) in early spring is a major constraint for maize production in Central and Northern Europe. Nutrient acquisition, nutrient uptake and particularly root growth are severely reduced at low RZT and the consequences of these growth depressions are frequently not completely compensated until final harvest. Perspectives to overcome these limitations by seed priming treatments with different micronutrients (Fe, Zn, Mn) were studied with maize seedlings exposed to low RZT (12 °C).Model experiments were performed in nutrient solution and soil culture using rhizo-boxes with root observation windows under green house conditions. To observe effects on final grain yield, additionally two field experiments were conducted in 2010 and 2011. Nutrient seed priming resulted in a significant increase in seed contents of the respective nutrients, i.e. Fe (25%), Zn (500%) and Mn (800%). At low RZT, biomass production and total root length of maize plants were significantly increased after Fe and Zn + Mn priming treatments, both in nutrient solution and in rhizo-box culture. There was no prominent difference in shoot Fe, Zn, Mn and P concentrations but total shoot contents per plant were significantly increased after nutrient seed priming. Plant growth promotion and improved micronutrient status was detectable also under field conditions at 5 weeks after sowing. This offers perspectives for using micronutrient seed priming for improving early seedling development and plant nutrient status of maize under low temperature climatic conditions.     

植物生长调节剂在种子生产中的应用

对不同类型的植物生长调节剂在种子生产方面的应用进行了介绍,综述了近年来植物生长调节剂在控制花芽分化比例、提高坐果率和结实率、促进子粒充实以及降低种子的落粒性等方面的研究进展,并提出了其在提高种子产量的应用过程中需要注意的问题。     

The effect of intensity of selection during successive generations of seed multiplication,on the field performance of Brussels sprouts

An experiment in which two different intensities of selection were applied, in each of three successive generations, to two varieties of Brussels sprout showed that the progeny resulting from lax selection were frequently inferior in agronomic characteristics to those from the more stringent selection. In one of the varieties used, this inferiority took the form of an increase in the proportion of off-types, and in the other there was a decrease in yield.These results imply that deterioration in the agronomic value of a variety is likely to occur whenever standards of selection are relaxed, for example, to accelerate the multiplication of seed. It is suggested that such deterioration is most likely to occur in those characteristics for which selection has improved the uniformity of a variety but has produced only partial homozygosity over the range of loci affecting those characteristics.     

Variation in tolerance to radiant frost at reproductive stages in field pea germplasm

Radiant frost is a major abiotic stress, particularly at the reproductive stage, in field pea (Pisum sativum L.) grown in Mediterranean environments. Here, response to frost was studied for flowering stage (FS) organs (buds, flowers and set pods) and pod development stage (PDS) organs (flat, swollen and mature pods) under controlled conditions, with plants exposed to a minimum temperature of –4.8°C for 4 h. This frost treatment adversely affected seed yield through (i) abortion of buds, flowers and set pods (ii) death of pods and (iii) reduction in seed size. FS organs were more sensitive to frost than PDS organs. Genetic variation was observed among 83 accessions collected from 34 countries worldwide for survival of FS buds, flowers and set pods. In 60 of 83 accessions, no buds, flowers or set pods survived the frost treatment. Five accessions: ATC 104 (origin: United Kingdom), ATC 377 (Estonia), ATC 968 (Italy), ATC 3992 (Kazakhstan) and ATC 4204 (China), showed the highest frost tolerance of FS organs and lowest numbers of abnormal seeds. The frost tolerant accessions identified in this study may be useful as parents for breeding field pea varieties that will be less likely to suffer yield loss due to radiant frost during the reproductive stage.