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Abstract [Objective] This study aims to examine the effects of container type and specification on the growth, blooming, and physiology of purple-leaf Lagerstroemia indica seedlings. The goal is to examine the optimal seedling container for the cultivation of purple-leaf L. indica seedlings and to provide basis for effective seedling breeding in containers. [Methods] Taking the excellent new variety ‘Ebony Embers’ of purple-leaf L. indica as research materials. Three type containers, black plastic nutrient cups (C1), white nonwoven beauty planting bags (C2), and black root-control containers (C3), with three specifications (diameter×height, cm) of 16×16 (D1), 21×21 (D2), and 25×25 (D3), were selected to set nine treatments. Seedlings under different treatments were measured for growth, flowering, and physiological indexes. [Results] (1) Different nursery containers had significant effects on the growth, flowering, and physiology of purple-leaf L. indica seedlings. The growth, root system, biomass, flowering period, flower diameter, inflorescence, soluble protein content, soluble sugar content, relative chlorophyll content, net photosynthesis rate, stomatal conductance, transpiration rate, and other indexes in the same container type were increased with the increase in the specification of the containers. (2) Diameter growth, total root length, total root surface area, total root volume, number of root tips, aboveground dry mass, belowground dry mass, total dry mass, and flowering time were greatest in the C3D3 treatment, which was higher than the smallest C1D1 treatment by 817.12%, 108.12%, 94.60%, 75.66%, 144.14%, 135.67%, 228.45%, 164.65% and 34.48%, respectively. Seedling height growth, crown growth, leaf area, and inflorescence length and width were the highest in the C1D3 treatment, which was higher than the lowest C1D1 treatment by 116.05%, 81.39%, 114.95%, 70.44%, and 65.79%, respectively. Relative chlorophyll content and water use efficiency were the greatest in the C3D3 treatment, while soluble protein and soluble sugar content, net photosynthetic rate, and stomatal conductance were the highest in the C1D3 treatment. The intercellular CO2 concentration and water use efficiency did not differ significantly among the treatments. (3) The comprehensive analysis score for each index was as follows: C3D3>C1D3>C2D3 >C3D2>C2D2>C1D2>C2D1>C3D1>C1D1. [Conclusion] The black root-control container performs well in terms of diameter growth, root growth index, biomass, flowering time and diameter, relative chlorophyll content, and net photosynthetic rate. The most suitable container for 2-year-old seedlings of purple- leaf L. indica is the black root-control container with a diameter of 25 cm and a height of 25 cm.

Male sterility is a common phenomenon in higher plants and often plays an important role in the selection of superior offspring. 'Xiang Yun' is a mutant of Lagerstroemia indica that does not bear fruit after flowering, and its flowering period is significantly longer than that of normal L. indica. To explore the timing and molecular mechanisms of sterility in 'Xiang Yun', this study determined the period of sterility through anatomical observation and compared the content of nutrients and the activity of antioxidative enzymes at different stages of flower development. Finally, sequence alignment and qPCR were used to analyze the differences in pollen development genes between 'Xiang Yun' and 'Hong Ye'. The results showed that the anthers of 'Xiang Yun' dispersed pollen normally, but the pollen grains could not germinate normally. Observations with scanning electron microscopy revealed that the pollen grains were uneven in size and shriveled in shape. Further observation of anther sections found that abnormal development of the microspores began at the S2 stage, with the callose wall between microspores of 'Xiang Yun' being thicker than that of 'Hong Ye'. In addition, during the flower development of 'Xiang Yun', the contents of soluble sugar, soluble protein, free proline, and triglycerides were deficient to varying degrees, and the activities of POD, SOD, and MDA were lower. Sequence alignment and qPCR showed that there were several mutations in EFD1, TPD1, and DEX1 of 'Xiang Yun' compared with 'Hong Ye', and the expression levels of these genes were abnormally elevated in the later stages of development. Our results clarified the timing and phenotype of male sterility in 'Xiang Yun'. This provides solid and valuable information for further research on the molecular mechanism of sterility in 'Xiang Yun' and the genetic breeding of crape myrtle. [ABSTRACT FROM AUTHOR]

One of the main reasons for the low yield of Camellia oleifera Abel is the large number of flowers and fruits that fall off before ripening. The aim of this study was to investigate the effect of foliar spraying of potassium dihydrogen phosphate (KH2PO4) on the fruiting characteristics of C. oleifera, and to provide technical support for its flower and fruit preservation and yield increasing. Three C. oleifera cultivars, 'Changlin 18', 'Changlin 166', and 'Changlin 40', were used as experimental materials to conduct foliar spraying experiments with different water concentrations of KH2PO4. The effects of KH2PO4 on the fruit retention rate, fruit properties, and seed oil quality of each cultivar were measured and analyzed. The application of the optimal concentration of KH2PO4 significantly enhanced various fruit quality metrics of three C. oleifera cultivars. Specifically, the total fruit retention rate was increased by 30.02~87.53%, the transverse diameter by 7.36~21.21%, and the longitudinal diameter by 18.56%, and the fruit weight of 'Changlin 40' could increase by 83.63%. It also increased dry seed yield by 27.87~80.81%, dry kernel rate by 10.29~30.12%, dry seed oil content by 28.00~29.77%, total unsaturated fatty acids (TUFAs) by 0.63~5.3%, monounsaturated fatty acids (MUFAs) by 0.30~5.37%, and squalene by 0.09~0.14% during the maturing stage. However, camellia cultivars had the different responses to KH2PO4 concentrations. To promote the fruiting of C. oleifera, improve the economic traits of fruits, and enhance the quality of tea oil, the recommended concentrations of KH2PO4 solution are 4.50 g·L−1, 1.50 g·L−1, and 1.50 g·L−1, for mist spraying on the trees of 'Changlin 18', 'Changlin 166', and 'Changlin 40', respectively. For mixed cultivars of C. oleifera which planted randomly, the recommended concentration range of KH2PO4 solution for spraying is 1.50 to 4.50 g·L−1. [ABSTRACT FROM AUTHOR]

Lagerstroemia indica is an important ornamental tree worldwide. The development of cultivars with colorful leaves and increased ornamental value represents one of the current main research topics. We investigated the anthocyanin profiles in two contrasting cultivars for leaf color phenotypes and explored the underlying molecular basis. Both cultivars display purple-red young leaves (Stage 1), and when the leaves mature (Stage 2), they turn green in HD (Lagerstroemia Dynamite) but remain unchanged in ZD (Lagerstroemia Ebony Embers). Seven different anthocyanins were detected, and globally, the leaves of ZD contained higher levels of anthocyanins than those of HD at the two stages with the most pronounced difference observed at Stage 2. Transcriptome sequencing revealed that in contrast to HD, ZD tends to keep a higher activity level of key genes involved in the flavonoid–anthocyanin biosynthesis pathways throughout the leaf developmental stages in order to maintain the synthesis, accumulation, and modification of anthocyanins. By applying gene co-expression analysis, we detected 19 key MYB regulators were co-expressed with the flavonoid–anthocyanin biosynthetic genes and were found strongly down-regulated in HD. This study lays the foundation for the artificial manipulation of the anthocyanin biosynthesis in order to create new L. indica cultivars with colorful leaves and increased ornamental value. [ABSTRACT FROM AUTHOR]