Symbiotic nitrogen fixation in black locust (Robinia pseudoacacia L.) seedlings from four seed sources

We conducted a greenhouse experiment to investigate the role of seed source in growth and symbiotic nitrogen fixation of black locust (Robinia pseudoacacia L). Seeds from different sources were planted in the same environmental conditions and inoculated with a suspension of mixed Rhizobium. We used the modified 15 N isotope dilution method to estimate biological nitrogen fixation of Robinia trees. Different Robinia seed sources differed significantly in terms of tissue dry weight (50.6 80.1 g), total N (1.31-2.16 g) and proportion of nitrogen derived from the atmosphere ( 0-51%). A higher nitrogen fixation rate of Robinia trees was associated with higher dry weight. Moreover, the leaves of Robinia proved to adequately represent the nitrogen fixation capacity of entire plants. Our results confirmed that assessment of seed sources is a useful way to improve the nitrogen fixation capacity and therefore the growth rate of Robinia.     

关于棉花种子问题的思考

棉花种子是棉农发展棉花生产,夺取棉花丰收的基本生产资料.近年来随着种子市场的放开,棉种的竞争日益强烈,各种棉花种子冲击市场,造成了棉花品种的新一轮多乱杂的现象.据湘北某市(县级)调查进入棉区的棉花品种近40个,并且还以每年10来个新品种的速度挤入棉种市场.种植面积最大的品种不到600公顷.占棉花种植面积的10%以下,少的仅几十公顷.严重影响棉花生产健康发展,影响着棉农的增产增收,影响着棉花产品市场的竞争力.     

甘蔗间作花生播期筛选试验

以粤油7花生为间作试验材料,探索研究甘蔗间作花生不同播期对花生农艺性状、经济性状和产量指标的影响。结果表明,在同等管理和施肥条件以及保证甘蔗生长发育的前提下,以第3播期（3月15日）间套作表现最佳,花生株高一般,有效分枝最多,单株果数最多,产量最高,袁综合经济效益最高。     

Inter-population variabilities in seed mass and germination of Panicum turgidum and Pennisetum divisum in the desert of Kuwait

Understanding variability in seed germination among populations is essential for planning an effective germplasm collection for restoration and conservation purposes.The knowledge of germination and dormancy patterns among populations of desert grasses is crucial for determining the potential of the species and populations to be used for restoration and conservation as well as forage production.Variability in seed germination of Panicum turgidum Forssk and Pennisetum divisum(Gmel.)Henr.in the desert of Kuwait was evaluated in different populations in May 2017.Experiment of seed germination(25 seeds and 4 replicates)was conducted for each population at night/day temperatures of 15℃/20℃and 20℃/30℃under the following light condition:continuous darkness or 12 h/12 h light/dark.Results showed that seed masses of both species strongly varied according to their seed provenances,and both species produced heavier seeds in population with a higher soil electrical conductivity.Seed germination percentage considerably varied between two species,and the variation in P.turgidum was greater(17%–49%)than that of P.divisum(72%–93%).Germination percentage in P.turgidum was greater at high temperature(20℃/30℃)than at low temperature(15℃/20℃).However,temperature regimes had no effect on germination percentage of P.divisum seeds.Mean germination time of both species exhibited significant inter-population variability.This result is especially relevant to assure the selection of the best population of each species and the regeneration success of the species.Besides this,inter-population variability also provides valuable information for enhancing our understanding of the mechanisms that regulate seed germination and how they might be related to seed provenance.     

Reproduction of Hedysarum scoparium (Fabaceae) in patched habitat is pollen limited, but not just pollinator limited

Pollen limitation of plant reproduction occurs across Angiosperms,particularly those in patched habitats.We investigated the relationship between pollen limitation and patch variables (patch size,visitation frequency) in the desert plant Hedysarum scoparium (Fabaceae),which is an important xerophyte in the arid and semi-arid regions of Northwest China and can grow well as a pioneer plant in shifting sand dunes.We observed insect visitation to H.scoparium over two flowering seasons and estimated pollen limitation using fruit set and seed production.Our results indicate that fruit set and seed production increased significantly with pollen supplementation compared with open pollination.Hedysarum scoparium was pollinated by over 8 species of bees,with 88.4% of visits made by introduced honeybees (Apis mellifera).Bee visitation varied significantly among the patches of habitats,but not associated with patch size of habitat.In general,pollen limitation occurred more strongly during fruit set than during seed production.The patches that received higher rates of pollinator visits were less pollen limited for fruit set.Pollen limitation for seed production,however,was not associated with pollinator visitation frequency.We conclude that pollen limitation in H.scoparium was caused by more than one reason,not just pollinator visits.     

Improving the assessment method of seed vigor in Cunninghamia lanceolata and Pinus massoniana based on oxygen sensing technology

Oxygen sensing technology was employed to study the rapid methods for seed vigor assessment of Chinese fir (Cunninghamia lanceolata) and Masson pine (Pinus massoniana). Firstly, seeds of five lots were performed using accelerated aging (AA) into three vigor levels. Then, four oxygen sensing indices, including increased metabolism time (IMT), oxygen metabolism rate (OMR), critical oxygen pressure (COP), relative germination time (RGT) and the control indices such as laboratory germination indices, dehydrogenase activity (DA), and electrical conductivity (EC) were analyzed by the tests of 15 samples. The results of correlation analysis between these indices and field emergence performances based on two-year and two-spot data showed that RGT and OMR should be indicated as the optimal oxygen sensing indices to rap- idly and automatically evaluate seed vigor of Chinese fir and Masson pine, respectively. On the basis, one-variable linear regression equations were built to forecast their field emergence performances by the two oxygen sensing indices.     

Breaking seed dormancy in Cupressus atlantica Gaussen, an endemic and threatened coniferous tree in Morocco

Cupressus atlantica Gaussen (Cupressaceae) is an endemic and endangered coniferous tree geographically restricted to the N’Fis valley in South-Western Morocco. Like many forest species, C. atlantica exhibits dormancy which delays and reduces germination. To improveseed germination, different pre-treatments were conducted on C.atlantica seeds after storage for different periods (one, two and five years) including: scarification with sandy paper; soaking seeds in hot distilled water at 60℃and 80℃for 15 min and soaking seeds for 48 h in agibberellic acid (GA3) at 1,000 and 2,000 mg·L-1. Results showed that scarification with sandy paper increased the germination rate of Atlas cypress by up to 67%, indicating that the species possess essentially anexogenous dormancy (physical dormancy) due to the hard seed coat(hardseededness). Exogenous application of gibberellic acid (GA3) at1,000 mg·L-1 was also effective in breaking seed dormancy and germination induction. These two treatments induced faster speed germination expressed by low number of days to first germination (8 10days) and low values of mean germination times (MGT). However,germination rate, under any treatment, is greatly dependent on the year of seed collection. Seeds collected in year 2004 gave the highest value,suggesting that even after five years of storage, the germination capacity of C. atlantica seeds could remain high. This observation is very interesting in the exsitu conservation of such endemic and endangered species where the production of seeds is irregular over the years.     

Provenance variation in cone and seed characteristics of Cedrus deodara (D. DON) G. DON in Jammu and Kashmir

The present study was carried out in Jammu and Kashmir (India) and twelve sites spread across the entire state were selected.Variability studies in different seed sources of Cedrus deodara with respect...     

科尔沁沙地75种植物结种量种子形态和植物生活型关系研究

研究了科尔沁沙地75种植物的结种量、种子形态、植物生活型关系.结果表明,灌木和半灌木(小半灌木)的结种量比草本植物的大;就草本植物而言,多年生植物的结种量较一、二年生植物的小;植物结种量和种子重量之间存在显著负相关;植物结种量和种子形状之间存在显著负相关,即种子越接近圆球形,结种量越大;占绝大多数的草甸植物结种量相对较小;而在物种数占总物种数的百分数相近时,草原植物的结种量最小,沙生植物的最大,杂草植物居中.     

提升企业核心能力 促进种业壮大发展

《中华人民共和国种子法》的颁布实施,促进了种业的快速发展,种业生产经营的垄断被打破,涌现出一大批股份制、民营优秀企业。这些企业在市场上不断扩大自己的市场份额,但由于国内种业经营管理水平相对落后,营销多沿袭原有的渠道模式,拼价格、拼返利,效果并不理想。随着产品日益同质化和渠道的多元化,