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Key message: Fifteen stable QTLs were identified using a high-density soybean genetic map across multiple environments. One major QTL, qIF5-1, contributing to total isoflavone content explained phenotypic variance 49.38, 43.27, 46.59, 45.15 and 52.50%, respectively.Abstract: Soybeans (Glycine max L.) are a major source of dietary isoflavones. To identify novel quantitative trait loci (QTL) underlying isoflavone content, and to improve the accuracy of marker-assisted breeding in soybean, a valuable mapping population comprised of 196 F7:8–10 recombinant inbred lines (RILs, Huachun 2 × Wayao) was utilized to evaluate individual and total isoflavone content in plants grown in four different environments in Guangdong. A high-density genetic linkage map containing 3469 recombination bin markers based on 0.2 × restriction site-associated DNA tag sequencing (RAD-seq) technology was used to finely map QTLs for both individual and total isoflavone contents. Correlation analyses showed that total isoflavone content, and that of five individual isoflavone, was significantly correlated across the four environments. Based on the high-density genetic linkage map, a total of 15 stable quantitative trait loci (QTLs) associated with isoflavone content across multiple environments were mapped onto chromosomes 02, 05, 07, 09, 10, 11, 13, 16, 17, and 19. Further, one of them, qIF5-1, localized to chromosomes 05 (38,434,171–39,045,620 bp) contributed to almost all isoflavone components across all environments, and explained 6.37–59.95% of the phenotypic variance, especially explained 49.38, 43.27, 46.59, 45.15 and 52.50% for total isoflavone. The results obtained in the present study will pave the way for a better understanding of the genetics of isoflavone accumulation and reveals the scope available for improvement of isoflavone content through marker-assisted selection. [ABSTRACT FROM AUTHOR]

Hole-insertion grafting method is widely used for cucurbit crops. The method establishes a very strong graft union without grafting clips. The key of successful grafting is to make hole at an optimal angle in the removed bud region so that the edge where the tool comes out through hypocotyls was below the opposite cotyledon. So during the hole-insertion grafting, the insertion angle is an important factor for the quality and survival of grafting plants, and mechanical stability. This study aimed to assess common rootstock and scion grafting cultivation in pumpkin, cucumber and watermelon, and investigated the effect of the insertion angle on the grafting mechanize. To achieve the objectives, structure parameters of rootstock and scion were measured, internal structure of hypocotyl growing point was analyzed by image analysis technique. The model was developed. The maximal insertion angle (75°) was determined by the grafting requirement that the insertion should avoid damaging cotyledon and entering hypocotyl cavity. The results showed that the insertion angle of perforate stick was not more than 75° for avoiding the insertion into the hypocotyls cavity. The aim of this study was to develop the semi-automatic grafting mechanism for grafted seedling on the basis of the hole-insertion grafting method and the insertion angle, which the grafting mechanism was adjustable in the range of 45°-75°. The experiment was carried out for researching the insertion angle of pumpkin and cucumber seedling using the grafting mechanism. In this experiment, the insertion angles were respectively set at 45°, 50°, 55°, 60°, 62°, 65°, 70°. In this grafting processing, the rootstock seedling and scion seedling were placed respectively in the rootstock clamping device and scion clamping device by operator, the grafting mechanism automatically completed clamping, punching, cutting and inserting. This report investigated shaping position and matching between the scion and the rootstock base on the structure for grafted seedlings by using image analysis technique. In this grafting method, grafted cuttings will be rooted and inserted in a new tray containing well watered medium, and healed at the same time inside a healing chamber. It is important to keep grafting seedling in a high moisture environment during the formation of the grafting union and healing period. In this experiment, grafted seedlings were placed in 95% humidity, temperature 26-28°C during day and 19-21°C during night, and complete darkness for initial 3 days. After 3 days of darkness, light was added. The experiment results showed that the rate of scion inserted into the rootstock cavity was low with the insertion angle of 60°, the successful ratio of grafting mechanism was high, and grafting survival rate was 91%. This method was effective in the view of punching, cutting and grafting process. [ABSTRACT FROM AUTHOR]