盐胁迫对两种无芒雀麦种子萌发的影响

 在实验室中对两种无芒雀麦本地种（Bromus inermis cv. Xilinguole）和引进种 (Bromus stamineus)种子在浓度为0.5%、1.0%、1.5%的Na₂SO₄、NaCl和MgCl₂ 3种单盐胁迫下进行发芽实验，结果表明：与对照相比，在以上3种盐胁迫下，随着胁迫浓度的增加，两种无芒雀麦种子的发芽率、发芽指数和发芽值均有不同程度的降低，相对盐害率升高，种子开始发芽的时间推迟且其发芽过程延长；在3种盐中，NaCl的胁迫对两种植物种子萌发的抑制作用最大，其中浓度为1.0% NaCl的胁迫对引进种和本地种无芒雀麦发芽率的抑制分别达到了68.67%和14%，在浓度为1.5%的NaCl胁迫下两种供试植物的发芽率均为零；通过建立不同盐分处理与两种无芒雀麦种子发芽率之间的回归方程得出，引进无芒雀麦种子芽期的耐盐性较本地无芒雀麦强。     

EFFECT OF SILICON SUPPLY ON GROWTH,FERTILITY, AND MINERAL COMPOSITION OF AN ANNUAL BROME,BROMUS SECALINUS L. (GRAMINEAE)

A study of the effects of three levels of silicon nutrition, representing low, intermediate, and high levels, shows that silicon does not enhance the vegetative growth of Bromus secalinus (cheat), yet it increases the rate of seed development and the efficiency of seed set. Grasses supplied with silicon have a higher percent of viable seeds compared to those grown in very low levels of silicon. Silicon supply, however, is not an absolute requirement for cheat reproduction, since grasses growing in low silicon levels set flowers and seeds, and the average weight of individual seeds or the mean number of inflorescences per plant are not influenced by silicon nutrition. Concentrations of silicon in tissues of cheat increase over time and with higher levels of silicon supply. Considerable differences are found in the silicon content of various vegetative and reproductive parts of cheat. Among vegetative parts, levels of silicon are lowest in stems and highest in green and senescent leaf blades. Among reproductive parts, silicon is most highly concentrated in the husks (glumes, lemmas, and paleas) surrounding filled seeds and is almost nonexistent in the seed itself. Mechanisms influencing silicon deposition and the ecological significance of the present findings are discussed.     

悬钩子属和蔷薇属的新植物

本文发表了山莓两个新变型和小果蔷薇一新变型,即粉红山莓Rubus corchorifolius L.f.f.roseolus Z.X.Yu、重瓣山莓R.cor-chorifolius L.f.f.Hemi semiplenus Z.X.Yu,还有重瓣小果蔷薇Rosa cymosa Tratt.f.plena Z.X.Yu et G.Z.Liu。     

SEX ALLOCATION AND OUTCROSSING RATE: A TEST OF THEORETICAL PREDICTIONS USING BROMEGRASSES (BROMUS)

Predictions of sex-allocation theory were tested by comparisons among hermaphroditic bromegrass (Bromus) species that differed in outcrossing rate. Relative maternal and paternal investment were calculated using both the ratio of pollen to seed production, and absolute allocations in units of energy, nitrogen, phosphorus, potassium, magnesium, and calcium. Outcrossing rate had a large effect on sex allocation; species having greater outcrossing rates had relatively more paternal reproductive effort. Bromus inermis was obligately outcrossing, and nearly half of its reproductive effort was devoted to pollen production. Three partially outcrossed species, B. kalmii, B. ciliatus, and B. latiglumis, invested between 5% and 11% of reproductive effort in pollen production. Paternal investment was less than 2% in the selling species B. tectorum. Estimates of sex allocation were relatively unaffected by the resource currency used in calculation. The differences among species in sex allocation were mostly due to differences in anther size and seed set.>     

REPRODUCTIVE BIOLOGY OF SEVERAL BROMEGRASSES (BROMUS): BREEDING SYSTEM,PATTERN OF FRUIT MATURATION,AND SEED SET

Five species of Bromus were tested for self-fertility when bagged. Bromus inermis was self-incompatible. Bromus tectorum, B. kalmii, B. ciliatus, and B. latiglumis were capable of self-fertilization. Further evidence from flowering behavior suggested that B. tectorum almost always self-pollinated and that the remaining self-fertile species sometimes outcrossed. Florets in different positions on a spikelet varied in the proportion that set seed. Open-pollinated B. inermis plants had lower seed set than the self-fertile species, in agreement with the pattern in a variety of hermaphroditic plants.