The Effects And Molecular Regulation Of K And Ca And Mg Applied In Foliar Nutrients Of Litchi Chinensis Sonn. Cv Sanyuehong

Sanyuehong Litchi (Litchi chinensis Sonn cv Sanyuehong) matures in late March to early April in Hainan province. It is the important early subtropical fruit varieties, which is indigenous to South China. But the pericarp coloring and flesh flavour quality of Sanyuehong litchi are not synchronous development, greatly reduce its market value and consumer acceptance. The author’s research group has reported:foliar application of P, K and Ca fertilizer can promote pericarp coloring in fruit swelling period of Sanyuehong litchi, and then could solve the problem of non-synchronization development between the pericarp coloring and flesh flavour quality. This paper based on the foliar application of potassium, calcium and magnesium single fertilizer and their mixed fertilizer, screening out the best fertilization treatment of solving pericarp coloring and flesh flavour quality synchronous development to investigate the physiological and molecular moderating mechanism of fertilization on Sanyuehong litchi pericarp coloring. It aims to enrich and develop the theory of physiological fruit ripening and lay the theoretical foundation for cultivation techniques of genetic improvement and optimization in litchi.1. With the growth and development of fruits of the different treatments and CK, the values of h, the contents of the chlorophyll in pericarp decreased generally, the values of a and the contents of anthocyanin in pericarp increased generally, he dynamic changes of the different treatments on the values of h in pericarp showed significant difference at the later stage. The value of h in pericarp of the treatment Ca+Mg dropped to the bottom and was significantly lower than those of CK and the other treatments on April 27th, since then to April 30th, the value of h in pericarp of the treatment Ca+Mg showed no significant difference, while those of the other treatments and CK were significantly decreased. The treatment Ca+Mg solved the problem that the stage green of pericarp.2. With the growth and development of fruits of the different treatments and CK, the contents of the total acid in flesh decreased generally, the contents of sugar and the ratio of sugar/acid in flesh increased generally. The dynamic changes of the different treatments on the ratio of sugar/acid in flesh showed significant difference at the later stage. From April 27th to April 30th, the ratio of sugar/acid in flesh of the treatments Ca and Mg showed no significant difference, while those of the other treatments and CK were significantly decreased, and the ratio of sugar/acid in flesh of the treatment Ca was significantly higher than that of CK.. The treatment Mg relieved the problem that the ratio of sugar/acid in flesh dropped when the pericarp coloring full.3. In the course of the development of the pericarp’s reddening, the different foliar nutrients treatments and CK could all improve the contents of the corresponding elements in pericarp. The partial correlation coefficients between the contents of the water-soluble Ca and the water-soluble K, the total Ca and the water-soluble K, the total Mg and the total Ca the water-soluble K and the total Ca、the water-soluble K and the total Mg、the water-soluble Mg and the total Ca、the total Ca and the total Mg were significant positive relationship. The multiple correlation coefficients between one of the contents of the total and the water-soluble K、Ca and Mg and the other five ones rest were respectively significant.4. The higher content of the water-soluble Mg in pericarp of the treatment Mg and CK was the key factors improving the pericarp’s reddening, the higher content of the total Ca in pericarp of the treatment Ca was the key factors improving the pericarp’s reddening, and the higher content of Ca and water-soluble Mg in pericarp of the treatment Ca+Mg was the key factors improving the pericarp’s reddening. To the different treatments and CK, the exponential regression equations of the contents of the anthocyanin to those of the total Mg, the water-soluble Ca and the total Ca in pericarp indicated significant respectively positive correlations, while the exponential regression equations of the contents of the chlorophyll to those of the water-soluble Ca in pericarp were significant respectively negative correlations. In conclusion, the element Ca and Mg have a synergistic effect with the growth and development of pericarp in Sanyuehong litchi, and different treatments promoted peel coloration by increasing the contents of Ca, Mg.5. There was no significant effect on the contents of IAA, GA3, Zeatin and the activity of Chlase of Ca+Mg treatment and CK in pericarp during the growth and development of litchi. In the late coloring stage, the treatment of Ca+Mg was higher on the contents of ABA, ethylene and the activities of UFGT, PaO.6. And the content of anthocyanin was significantly positively correlated with the activity of UFGT, the content of ABA and ethylene; the content of chlorophyll was significantly negatively correlated with the activity of PaO, the content of ABA and ethylene.7. RNA-seq of the treatment of Ca+Mg and CK received 56856 unigenes. There are 31629 unigenes can annotate in four databases by Blast analysis. These unigenes has homo logy with about 433 species, related to 25 classes physiological processe which included in COG proteins and 36 GO branches. These unigenes also related with 124 kinds of metabolic pathways including physiological processes of pigment metabolism (anthocyanin, chlorophyll, carotenoids, flavonoids, flavonoids etc.) and hormone and signal transduction. Treatment and CK samples have different up- regulated and down-regulated expression during different growth and development. DEGs are concentrated on COG, GO and Pathway, in which the pathway of plant hormone signal transduction differentially expressed in the most significant, and mainly in the ABA metabolic pathways. And DEGs of Ca+Mg treatment expressed higher substantially than the CK treatment in late coloring stage. So Ca+Mg treatment promoted the pigmentation by ABA metabolism in pericarp of Sanyuehong litchi, and then solved the problem "stay-green".