Effects of simulated acid rain on fertility of litchi

The regulatory role of calcium in fertility of pollen and pistil under simulated acid rain was investigated. The germination percentage of pollen treated with acid rain of pH 4.5 was 9.42% lower than that of control, and that of pH 3.5, pH 2.5 and pH 1.5 were 22.47%, 45.49% and 71.62%, respectively. Simultaneously, the injury character of pollen was obviously observed when flowers were treated with acid rain of pH 3.5. The difference in fruit setting rate between the female flower treated with acid rain of pH 4.0 and the control was significant at p 〈 0.05. Ca（NO3 ）5 of 0.2-0.4 mmol/L could promote pollen germination under the stress of acid rain. The beneficial function was reduced when calcium concentration surpassed 0.8 mmol/L. Spraying 2 mmol/L Ca（NO3 ）5 reduced the injury of acid rain to pistil and increased fruit-setting rate significantly. The physiological importance of calcium during pollen germination and pistil development was also discussed.

What are the differences in yield formation among two cucumber (Cucumis sativus L.) cultivars and their F1 hybrid?

To elucidate the mechanisms underlying the differences in yield formation among two parents(P1 and P2) and their F1 hybrid of cucumber, biomass production and whole source–sink dynamics were analyzed using a functional–structural plant model(FSPM) that simulates both the number and size of individual organs. Observations of plant development and organ biomass were recorded throughout the growth periods of the plants. The GreenLab Model was used to analyze the differences in fruit setting, organ expansion, biomass production and biomass allocation. The source–sink parameters were estimated from the experimental measurements. Moreover, a particle swarm optimization algorithm(PSO) was applied to analyze whether the fruit setting is related to the source–sink ratio. The results showed that the internal source–sink ratio increased in the vegetative stage and reached a peak until the first fruit setting. The high yield of hybrid F1 is the compound result of both fruit setting and the internal source–sink ratio. The optimization results also revealed that the incremental changes in fruit weight result from the increases in sink strength and proportion of plant biomass allocation for fruits. The model-aided analysis revealed that heterosis is a result of a delicate compromise between fruit setting and fruit sink strength. The organlevel model may provide a computational approach to define the target of breeding by combination with a genetic model.

A Study on the Xenia Effect in Castanea henryi

The xenia effect results in pollen affecting the setting rate and the appearance and quality of fruits. To further understand this phenomenon,we investigated the xenia effect in Castanea henryi using the cultivars ‘Huali 1', ‘Huali 2', ‘Huali 3', and ‘Huangzhen' as materials. Twenty combinations of self-, cross-, and natural pollination were undertaken in a chestnut orchard in Chenzhou City, Hunan Province, China. Significant differences were observed among the pollination combinations in terms of the time of fruit ripening, rate of fruit setting, size of the barbed shell and nut, and content of soluble sugars, fats, proteins, amylose, and vitamin C. No significant differences were observed with regard to nut rate,content of total starch, and moisture content. The fruit quality of the 20 pollination combinations was evaluated using a subordinate function method,and showed that Huali 2 × Huali 3 was the best combination, and Huangzhen × Huangzhen was the most ineffective combination. Therefore, we recommend the combination of Huali 2 × Huali 3 for the future production of C. henryi.

Do different measures of maternal fitness affect estimation of natural selection on floral traits? A lesson from Linum pubescens (Linaceae)

Aims Floral traits in animal-pollinated plants are proposed to be selected by the behavior of pollinators,which create differential fitness.However,fitness estimation is not trivial and there is no agreed or universal measure of fitness.in plants,fitness can be measured in various ways,including the number of fruits or seeds,probability of survival,or growth rate.Methods Because each fitness measure can be associated with different pol-linator behavior,estimating pollinator-mediated selection on floral traits can differ among various fitness measures.We used the annual Mediterranean plant,Linum pubescens,as a model to assess the relative role of various fitness measures in estimating pollinator-mediated selection on floral traits.We compared four maternal fit-ness measures and estimated their relative advantage in assessing natural selection on floral traits of L.pubescens.To identify whether each trait is under pollinator-mediated selection,we used media-tional analysis.Important Findings We found that each floral trait was under natural selection assessed by a different fitness measure.The color combination of floral tube throat and stamen color was under selection when using seed mass as a fitness measure,and floral diameter was under positive direc-tional selection when the number of seeds or number of fruits was used as a fitness measure.Selection on floral color was not mediated by pollinators’visitation rates,while flower diameter showed par-tial pollinator-mediated selection.We conclude that using several fitness measures gives an insight into the mechanisms underlying phenotypic selection on a floral trait,and facilitates the understand-ing of pollinator-mediated selection.