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.     

Combining Ability and Parent-Offspring Correlation of Maize (Zea may L.) Grain β-Carotene Content with a Complete Diallel

Vitamin A deficiency has become a worldwide problem. Biofortified foods can potentially be an inexpensive, locally adaptable, and long-term solution to dietary-nutrient deficiency. In order to improve the β-carotene content in maize grain by breeding and minimize vitamin A deficiency, a complete diallel cross was designed with eight inbred lines of maize, and 64 combinations were obtained in this study. The experimental combinations were planted in Yunnan and Sichuan provinces, respectively, with a random complete block design. The β-carotene contents in the grains of the experimental materials were analyzed by high-performance liquid chromatography. Among the tested materials, the effect difference of general combining ability of the β-carotene content was significant; however, the effect difference of the special combining ability and the reciprocal effect were not significant. The β-carotene content of maize grain was not influenced significantly by the cross and the reciprocal cross. There was a significant correlation about the β-carotene content in the maize grains between the F₁ and their parents. The combinations with high β-carotene content were obviously influenced by the environment, and the mean value of β-carotene content for the experimental materials planted in Ya'an of Sichuan was higher than that planted in Yuanjiang of Yunnan, with the results being significant at the 0.01 level.     

Cloning and Functional Analysis of Lycopene ɛ-Cyclase (IbLCYe) Gene from Sweetpotato,Ipomoea batatas (L.)Lam.

This paper reported firstly successful cloning of lycopene ε-cyclase (IbLCYe) gene from sweetpotato, Ipomoea batatas (L.) Lam. Using rapid amplification of cDNA ends (RACE), IbLCYe gene was cloned from sweetpotato cv. Nongdafu 14 with high carotenoid content. The 1 805 bp cDNA sequence of IbLCYe gene contained a 1 236 bp open reading frame (ORF) encoding a 411 amino acids polypeptide with a molecular weight of 47 kDa and an isoelectric point (pI) of 6.95. IbLCYe protein contained one potential lycopene ε-cyclase domain and one potential FAD (flavinadenine dinucleotide)/NAD(P) (nicotinamide adenine dinucleotide phosphate)-binding domain, indicating that this protein shares the typical characteristics of LCYe proteins. The gDNA of IbLCYe gene was 4 029 bp and deduced to contain 5 introns and 6 exons. Real-time quantitative PCR analysis revealed that the expression level of IbLCYe gene was significantly higher in the storage roots of Nongdafu 14 than those in the leaves and stems. Transgenic tobacco (cv. Wisconsin 38) expressing IbLCYe gene accumulated significantly more β-carotene compared to the untransformed control plants. These results showed that IbLCYe gene has an important function for the accumulation of carotenoids of sweetpotato.     

Seed Priming Influence on Early Crop Growth,Phenological Development and Yield Performance of Linola (Linum usitatissimum L.)

Reduced early crop growth and limited branching are amongst yield limiting factors of linola. Field response of seed priming treatments viz. 50 mmol L^-1 salicylic acid （SA）, 2.2% CaCl2 and 3.3% moringa leaf extract （MLE） including untreated dry and hydropriming controls was evaluated on early crop growth and yield performance of linola. Osmopriming with CaCl2 reduced emergence time and produced the highest seedling fresh and dry weights including Chl. a contents. Osmopriming with CaCl2 reduced crop branching and flowering and maturity times and had the maximum plant height, number of branches, tillers, pods and seeds per pod followed by MLE. Increase in seed weight, biological and seed yields was 9.30, 34.16 and 39.49%, harvest index （4.12%） and oil contents （13.39%） for CaCl2 osmopriming. Positive relationship between emergence and seedling vigor traits, 100-seed weight, seed yield with maturity time, 100-seed weight and seed yield were found. The study concludes that seed osmopriming with CaC12 or MLE can play significant role to improve early crop growth and seed yields of linola.