观赏海棠品种间的杂交亲和性研究和亲本选择

为筛选出优质亲本及杂交组合,确定最佳授粉时期,探究观赏海棠品种间的杂交亲和性,为观赏海棠的新品种培育提供参考,该研究以15个性状互补的海棠品种为供试材料,用离体培养法测定花粉活力、悬液法测定花粉含量并对其雄性育性进行评价;联苯胺-过氧化氢法测定其不同开花时期的柱头可授性;荧光显微观察法观察授粉后花粉管的生长及受精情况;人工控制授粉法研究5个杂交组合的坐果动态变化情况。结果显示,(1)根据花粉活力可将15个海棠品种的雄性育性分为不育型、较低型、中等型、优质型4类,其中‘印第安之夏’、‘冬红’等6个品种为优质父本。(2)海棠从开花前1 d至第6天的柱头可授性呈现“弱—强—弱”的变化规律,开花第3天时的柱头可授性最强。(3)授粉后4~8 h花粉开始萌发,48~96 h完成受精。(4)花粉育性和柱头可授性与杂交坐果率、种子饱满率间均存在显著的正相关性。授粉后2个月内是落果集中期,此后至果实成熟坐果率基本趋于稳定。‘冬红’ב印第安之夏’、‘草莓果冻’ב印第安之夏’为高坐果率杂交组合。研究表明,海棠雌雄蕊存在发育不同步现象,选择育性优质的亲本是杂交取得成功的关键,而受精后障碍是本研究中海棠杂交不亲和的主要原因。

Mechanistic studies on peroxymonosulfate activation by g-C3N4 under visible light for enhanced oxidation of light-inert dimethyl phthalate

Excitation of metal-free graphitic carbon nitride(g-C3N4) under visible light can successfully achieve efficient activation of peroxymonosulfate(PMS). Synergistic effects and involved mechanism were systematically investigated using a light-inert endocrine disrupting compound, dimethyl phthalate(DMP), as the target pollutant. Under visible light irradiation, DMP could not be degraded by direct g-C3 N4-mediated photocatalysis, while in the presence of PMS, the dominant radicals were converted from ·O2 to SO4·– and ·OH, resulting in effective DMP degradation and mineralization. Results showed that higher dosage of PMS or g-C3 N4 could increase the activation amount of PMS and corresponding DMP degradation efficiency, but the latter approach was more productive in terms of making the most of PMS. High DMP concentration hindered effective contact between PMS and g-C3 N4, but could provide efficient use of PMS. Higher DMP degradation efficiency was achieved at p H lower than the point of zero charge(5.4). Based on intermediates identification, the DMP degradation was found mainly through radical attack(·OH and SO4·–) of the benzene ring and oxidation of the aliphatic chains.

Dynamics of the Alpine Treeline Ecotone under Global Warming:A Review

The alpine treeline ecotone is defined as a forest-grassland or forest-tundra transition boundary either between subalpine forest and treeless grassland,or between subalpine forest and treeless tundra.The alpine treeline ecotone serves irreplaceable ecological functions and provides various ecosystem services.There are three lines associated with the alpine treeline ecotone,the tree species line(i.e.,the highest elevational limit of individual tree establishment and growth),the treeline(i.e.,the transition line between tree islands and isolated individual trees)and the timber line(i.e.,the upper boundary of the closed subalpine forest).The alpine treeline ecotone is the belt region between the tree species line and the timber line of the closed forest.The treeline is very sensitive to climate change and is often used as an indicator for the response of vegetation to global warming.However,there is currently no comprehensive review in the field of alpine treeline advance under global warming.Therefore,this review summarizes the literature and discusses the theoretical bases and challenges in the study of alpine treeline dynamics from the following four aspects:(1)Ecological functions and issues of treeline dynamics;(2)Methodology for monitoring treeline dynamics;(3)Treeline shifts in different climate zones;(4)Driving factors for treeline upward shifting.

Variations in Patch Use by Ruminant and Non-ruminant Herbivores in a Tropical Wildlife Reserve, Ghana

Food processing and consumption by herbivores are affected differently by the availability of forage quality and quantity per unit of time. This demonstrates the “Allometric response concept”, and it is considered a significant determinant in habitat use for foraging by grazers. The relevance of this approach has comprehensively been applied to herbivores of different body sizes, but little is known about its demonstration to explain patch use in herbivores with different digestive physiology and body size. We explain the use of patches by grazing herbivores of different digestive physiology and body sizes, Hippopotamus amphibius(hippopotamus, mega non-ruminant) and cattle(ruminant), by integrating foraging relationship herbivores. We analysed the significant relationships between species dropping densities and environmental variables across forty-eight 100 m×100 m plots in Bui National Park,Ghana, during the wet and dry seasons. We found that both species utilised areas closer to the river in the wet season, but the H. amphibius foraged further away from the river during the dry season. Sward height also determined patch use by both species, with the H. amphibius utilising shorter swards than the cattle. Considering the quality of food resources, the study revealed that patch selection of ruminants(cattle) was significantly influenced by nitrogen content. In contrast, acidic detergent fibre content was positively related to non-ruminant species(H.amphibius). The high seasonal effect of sward height and food quality on patch use is primarily due to the species digestive physiology and body size of hippopotamus and cattle at the Bui National Park.