A simulation model for assimilate partitioning between pods in pea (Pisum sativum L.) during the period of seed set; validation in field conditions

A theoretical model for assimilate partitioning among pods in pea is proposed. In this model, based on previous results from ¹⁴C-labelling experiments, assimilates produced are allocated to each pod in proportion either to their biomass (before the final stage in seed abortion) or to their seed number (after this stage). This model was tested against results obtained from field experiments. Pod growth at each node was measured between the beginning of flowering and the final stage in seed abortion of the last node on the stem. The model predicts the dry matter allocated to pods of each node between two successive sampling dates. Input data are: development parameters, total reproductive growth rate per stem, seed number in pods which have passed the final stage in seed abortion and the dry weight of pods which have not yet reached this stage at the first sampling date. Observed and predicted dry matter amounts allocated to the pods at each node between two sampling dates were highly correlated for all field situations, validating the proposed model.     

Microorganisms associated with natural fermentation ofProsopis africana seeds for the production of okpiye

Okpiye is a food condiment prepared by the fermentation ofProsopis africana seeds. The traditional process for the production and microbiological characteristics of the condiment were investigated. During laboratory fermentation that lasted 96h, the mesquite seeds underwent a natural fermentation that was characterised by the growth of microorganisms to 10⁶–10⁸ cfu/g. Several species of bacteria especiallyB. subtilis, B. licheniformis, B. megaterium, Staphylococcus epidermidis andMicrococcus spp were found to be the most actively involved organisms. However, significant contributions to the microbial ecology were made byEnterobacter cloacae andKlebsiella pneumoniae. Lactobacillus spp were present in low numbers towards the end of the fermentation. The presence ofProteus andPseudomonas spp in traditional fermented samples demonstrate the variability which may exist in the microflora of individual fermented samples. Variations in the important microbial groups show thatBacillus spp were the most prevalent species and occurred until the end of fermentation. Temperature, pH and titratable acidity varied with time and were influenced by the metabolic activities of the microorganisms.     

Effect of American bison (Bison bison L.) on the recovery and germinability of seeds of range forage species

Abstract The effect of passage through the digestive tract of Bison bison on the recovery and germinability of undamaged passed seeds of Pseudoroegneria spicata, Elymus cinereus, Oryzopsis hymenoides, Stipa comata, Balsamorhiza sagittata and Sphaeralcea coccinea was tested. Recovery of undamaged passed seeds peaked 2 days after ingestion and then decreased to the lowest level on day 5 of sample collection for all species used, but the pattern of seed passage through time significantly differed among species. Recovery of passed seeds was greatest for round‐shaped, hard seed‐coated O. hymenoides and lowest for largest seed‐sized B. sagittata. The digestive tract of B. bison did not break seed dormancy of O. hymenoides, S. comata, S. coccinea or B. sagittata. Germination percentage of P. spicata and E. cinereus seeds decreased compared with unpassed seeds of the same species.     

Preliminary investigations into the significance of floral applications of calcium,boron and polyphenols for increased seed set in confection sunflowers (Helianthus annuus L.)

One of the major problems of confection sunflowers is low seed set. We studied the relationship between seed set and the origin of pollen, either self or cross, and the effects of stigmatic sprays of calcium nitrate, boric acid and polyphenols on seed set. In a screen-house experiment, seed set was analyzed for three predetermined regions in the sunflower capitulum: distal, median and proximal. Cross-pollination combined with calcium nitrate or boric acid spray significantly improved seed set in the distal region compared with cross-pollination alone or with cross-pollination combined with self-pollination. Neither spray had a significant effect on seed set in the median or proximal regions. Cross-pollination of the proximal region only, with either fresh pollen or 24-h-old pollen, did not improve seed set compared with cross-pollination of the whole capitulum. We found no direct link between pollen germination on the stigma and seed set. However, each region of the capitulum responded differently to self- or cross-pollination. In two open-field experiments, stigmatic applications of calcium nitrate significantly increased seed set by approximately 9% compared with open pollination alone, while stigmatic applications of polyphenols significantly increased seed set by approximately 9% only once, suggesting that commercial yields may be increased by using similar applications.     

Soak conditions and temperature following sowing influence the response of maize (Zea mays L.) seeds to on-farm priming (pre-sowing seed soak)

On-farm seed priming of maize (i.e. soaking seed in water overnight, 17 h) in the semi-arid tropics has been shown to improve crop establishment and yield but the benefits can be variable. In previous work, this variation was thought to result from the interaction between primed seeds and conditions in the seedbed following sowing. To investigate this interaction, experiments were carried out under controlled temperature conditions that represented those of seedbeds in the semi-arid tropics. The conditions during seed priming and during subsequent germination and emergence were investigated as potential causes of variable seedling emergence relative to that of untreated seeds. Priming advanced emergence from moist sand cores at 30 °C/20 °C (day/night), reduced emergence at 35 °C/28 °C and delayed and reduced emergence at 40 °C/28 °C. In drier cores (drained 8 days) at 35 °C/28 °C, priming advanced germination time and did not decrease final percentage emergence. These results confirmed earlier field observations that the effect of priming in maize can vary and lead to positive, neutral or negative effects. Priming decreased the optimum and ceiling temperatures for germination, and unlike untreated seeds, the relationship between germination rate and sub-optimal temperature was not linear in all cases. Pre-humidifying seeds did not enhance the effect of priming, but aerating the soak water did. These results indicate that variable results from priming recorded in the field were not due to imbibitional damage, but may result from the negative effects of hypoxia during soaking exacerbated by moist conditions and high temperatures at sowing. These effects differed between seedlots of different cultivars, indicating the importance of selecting more tolerant maize hybrids to reduce variation in response to priming following sowing in the field. The implications of these findings for the use of primed seeds in the field are discussed.     

2001-2009年国家冬油菜区域试验参试材料分析

2001至2009年参加区域试验(以下简称区试)的595份品系申报材料分析结果表明:参试品系数量增长6倍,申报单位数量增长7.5倍.参试品系由常规种为主转变为以杂交种为主,杂交种比例均值达77.90%.育种中使用的授粉控制系统由细胞质不育系为主转变为细胞质和细胞核不育系兼用,2003年后利用核不育系选育的品种数量与细胞...     

A Kunitz-type proteinase inhibitor with differential solubility during the development of potato (Solanum tuberosum L.) tubers

Summary Two potato (Solanum tuberosum L., cv. Irish Cobbler) Kunitz-type proteinase inhibitors (PKPI) were previously described to be present in the soluble fraction of proteins from tubers in the early stages of development. One of them became insoluble in mature tubers, being extractable from this material in presence of urea. Amino acid sequencing showed that the soluble and insoluble PKPI were identical to each other. Also, immunolocalization using the protein A-gold method showed that both proteins were present inside the vacuole in free (intravacuolar space) and aggregated forms. The density of PKPI in the vacuolar protein aggregates increased from developing to mature tubers. showing that the soluble-insoluble state of this protein is related to the aggregation levels. Purified PKPI precipitated in vitro. mainly in presence of high calcium concentrations and low pH, but this precipitated form was not as stable as aggregates found in vivo. Based on the results obtained, a model of PKPI insolubilization in vivo is discussed.     

Genomic regions associated with the degree of red coloration in pericarp of rice (Oryza sativa L.)

The degree of red coloration (DRC) in pericarp of rice depends on the content of flavonoid compounds which have beneficial health effects for humans. In this study, 182 backcross-recombinant inbred lines (BILs) derived from Koshihikari (white pericarp)/Kasalath (red pericarp)//Koshihikari were used to detect the genomic regions associated with DRC through the QTL mapping approach. As a result, a total of four genomic regions were found to associate with DRC on chromosomes 1, 7, 9 and 11, respectively. Interestingly, the two genomic regions having the largest effects corresponded to previously characterized Rc and Rd genes on chromosome 7 and 1, respectively. In addition, two novel genomic regions having minor effects on DRC and located on chromosomes 9 and 11, respectively, are reported here for the first time. These results and the identification of tightly linked molecular markers that flank the genomic regions provide an opportunity for marker-aided improvement of red coloration in pericarp of rice.     

An SNP downstream of the OsBEIIb gene is significantly associated with amylose content and viscosity properties in rice (Oryza sativa L.)

Allele mining in starch synthesis-related genes (SSRGs) has facilitated the discovery of desired natural sequence variations for eating quality in rice. This study investigated the sequence variations from 10 SSRGs, and further evaluated their relationship with the amylose content (AC) and rapid viscosity analysis profiles in a global collection of rice accessions by association mapping (AM). In total, 83 sequence variations were found in 10 sequenced amplicons, including 73 single nucleotide polymorphisms (SNPs), eight insertion-deletions (InDels) and two polymorphic simple sequence repeats (SSRs). Four subpopulations were identified by population structure analysis based on 170 genome-wide SSR genotypes. AM revealed 11 significant associations between three phenotypic indices and three sequence variations. One SNP with a g/c transversion at the 63rd nucleotide downstream of the OsBEIIb gene termination codon on rice chromosome 2 was significantly associated with multiple trait indices in both the general linear and mixed linear models (GLM and MLM), including the final viscosity (p < 0.001, R² = 23.87%) in both 2009 and 2010, and AC (p < 0.01, R² = 11.25%) and trough viscosity (p < 0.01, R² = 20.43) in 2010. This study provides a new perspective of allele mining for breeding strategies based on marker-assisted selection.