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Effects of different nitrogen fertilizer application rates on fruit quality of pitaya under the condition of calcareous soil in karst area were discussed in order to investigate the effects of nitrogen fertilizer application level on fruit quality of pitaya under calcareous soil condition in karst area. The ‘Taiwan Dahong' pitaya were used as the experiment material. Based on 0.216 kg of phosphorus(P)and 0.324 kg of potassium(K), four nitrogen(N)application levels(CK, T1, T2, T3)were setted. Twenty-one fruit quality indexes were determined, and the quality differences of pitaya with different N application levels(CK, T1, T2, T3)were compared. At the same time, eleven appearance quality indexes were comprehensively analyzed by principal component analysis. The results were as follows: (1)Compared with the control, N application could increase the contents of soluble sugar and soluble solids of fruit, reduce the contents of protein and dietary fiber, and the high nitrogen treatment(T3)was significantly different from other treatments. With the increase of N application, the contents of titratable acid and vitamin C of fruit increased firstly and then decreased, while the solid-acid ratio decreased firstly and then increased. T3 significantly increased the fruit vertical and horizontal diameters, fruit shape index and single fruit weight. (2)Compared with the control, N application treatment reduced the N content of pitaya fruit and increased the P content, and the N and P contents of each treatment were significantly different. The K content of fruit increased with the increase of N application. N application increased fruit boron(B)content and decreased fruit cuprum(Cu)content. The contents of manganese(Mn), ferrum(Fe), calcium(Ca)and magnesium(Mg)in different treatments were ranked as T3 > T1 > CK > T2. The content of zinc(Zn)decreased firstly and then increased with the increase of N application. (3)The principal component comprehensive evaluation score of the high N treatment was the highest, indicating that when selecting brown calcareous soil in Guilin karst area to grow pitaya, supplemented by a certain amount of P and K fertilizers, high N treatment was more conducive to improving the quality of pitaya. Therefore, in actual production, it is necessary to make appropriate adjustments according to the soil fertility status of the plantation. [ABSTRACT FROM AUTHOR]

To investigate the effects of different supplemental light qualities on physiological characteristics of pitaya stems, red, white and blue lights were used as supplemental light sources at night. The contents of soluble sugar, soluble protein, chlorophyll, mitochondrial protein, mitochondrial membrane potential and three endogenous hormones(CTK, IAA, GA)were determined. The indicators of stem growth, flowering, fruit yield were counted. The results were as follows: Supplementing the three kinds of light could all increase the soluble protein contents in pitaya stems, and the white light had the best effect; Supplementing the three kinds of light could all significantly increase soluble sugar contents in pitaya stems, and the blue light had the best effect; Supplementing white light was beneficial to increase the contents of chlorophyll a and b, and supplementing red light had no significant effect on it, while blue light would reduce its content; Supplementing white light and blue light could significantly reduce the CTK contents, supplementing white light and red light could significantly increase the IAA contents, and supplementing red light and blue light could significantly increase the GA contents; Supplementing white light could significantly reduce the mitochondrial protein contents and the three kinds of supplement light had no obvious effect on the mitochondrial membrane potential; Supplementing the three kinds of light had no significant effects on the growth of pitaya stems, while supplementing red light and white light could significantly increase the flower formation rate, and supplementing red light could significantly increase the fruit yield. Comprehensive analysis deemed that supplementing red light and white light had obvious promoting effect on the contents of metabolites, chlorophyll, endogenous hormones of pitaya stems, flower formation rate and fruit yield. The research results can provide a reference for a technology of light quality controlling to improve the growth and development pitaya plants. [ABSTRACT FROM AUTHOR]

Different varieties have different resistances. In order to further explore the resistance differences in different varieties of pitaya and to provide a reference for further study on breeding of pitaya resistance, we used Illumina HiSeq 2000 sequence platform to sequence the transcriptomes of ‘Putongbairou'(BR)and ‘Ecuador Yellow'(EY). Functional classification and enrichment analysis of differentially expressed genes(DEGs)were performed by reference to GO Ontology, KEGG and others databases. The results were as follows:(1)There were 14 248 DEGs between BR and EY, of which 5 446 genes were up-regulated and 8 802 genes were down-regulated.(2)GO functional analysis showed that these DEGs were mainly involved in enzyme catalytic activity, cell components, metabolic processes, etc. Among them, there were 349 differential genes involved in oxidoreductase activity.(3)KEGG pathway analysis showed that most of the DEGs were enriched in metabolism, biosynthesis, etc., and 12 key genes such as CYP86 and CER1 involving in cutin, suberine and wax biosynthesis. We found that the expressions of DEGs involved in oxidoreductase activity were higher in BR than those in EY, which significantly enriched, indicating that may be significant differences in growth and cell metabolism between BR and EY. DEGs involved in the cutin, suberine and wax biosynthesis were up-regulated in BR, and such genes had higher expressions in BR, and were significantly enriched, which suggest that BR may be superior drought and disease resistance than EY. [ABSTRACT FROM AUTHOR]

Changing characteristics of soil mineral elements in different tillage methods were discussed in order to promote growth, development and quality improvement of pitaya. The evaluating indicator was conducted on 22 soil mineral elements in five tillage methods of pitaya land, the methods include interplant alfalfa(Medicago sativa), application of organic fertilizer, chemical fertilizer and pesticides, film mulching and no measures in study area, to compare the content differences of soil mineral elements in different tillage methods, correlation analysis was also performed to clarify the correlation between mineral elements in soil. The results were as follows:(1)Compared with no measures, the content of Ca, Si, Mn et al. showed an increasing trend, while the content of Fe, Mg, Al et al. decreased, and that the content of Na showed no significant difference.(2)About the supplement of mineral elements, the organic fertilizers applied were the most abundant, the second was plastic mulching, alfalfa is the worst.(3)According to the correlation analysis, there were correlations among soil mineral elements. Al, Si, S and Ni were closely related to other elements, while Fe, Mg, Na, Mn, Cu and Co had significant or extremely significant correlation between elements.(4)Besides, there was an extremely significantly or significantly negative correlation between Ca, Fe, Mg, Mn, Cu, Zn and B, antagonistic effect. When cultivated of pitaya in dry-hot valley rocky desertification region, the tillage method of applying organic fertilizer is the first choice for nutrient supplement. The deficiency of mineral elements caused by different farming methods should be timely supplemented, especially for Fe, Mg, Al, Na, Cu, Zn et al. [ABSTRACT FROM AUTHOR]