Spathiphyllum Schott is a perennial herb of Araceae, which is an important foliage plant for ornamental. Phenotypic diversity of germplasm resources is the basis of ornamental plants breeding and application. In the current study, 27 important ornamental traits of 20 Spathiphyllum germplasm resources were observed and the phenotypic diversity was analyzed by multivariate statistical analysis methods including variance analysis, correlation analysis, hierarchical cluster analysis (HCA) and principal component analysis (PCA). The results of variance analysis showed that the coefficients of variation of the 16 quantitative traits ranged from 27.2% to 69.9%. The plant height, number of shoots, number of leaves, blade width, petiole diameter, spadix length and number of flowers were highly variable, while the plant width and spadix diameter had small variation. Eleven descriptive traits could be divided into 2~4 grades according to the observed characteristics. And the Shannon-Wiener indices of 11 descriptive traits ranged from 0.20 to 1.01, among which the Shannon-Wiener indices of leaf shape were the highest, whereas that of perianth separation and perianth color were the lowest. The hierarchical cluster analysis tree of 27 traits supported that when the euclidean distance was 3, they could be divided into two groups: Group A and Group B. The result of Pearson correlation analysis revealed that the correlation coefficient between 27 traits ranged from -0.72 to 0.91. In Group A, most of the traits were significantly correlated with each other, and the correlation coefficients between bud length and bud width, bud length and inflorescence length were 0.91. In Group B, most of the traits pairs were not significantly correlated. Both hierarchical cluster analysis and principal component analysis supported that the 20 Spathiphyllum germplasm resources could be divided into 2 Groups (Group I and Group II) based on data of 27 traits. Group I contained 7 accessions including S. cannifolium, S. ortgiesii, S. Clevelandii, S. Bright, S. Princess, S. Middle Flower and S. Sensation, and they were taller and had larger leaves, larger spathes, and larger spadixes. Group II was consisted of S. floribundum, S. Coddy Color, S. Water Grass, S. Parrish, S. Mini, S. Vicki Lynn, S. Mojo, S. Tyler Green, S. Crisis, S. Sweet Chico, S. Sweet Claudio, S. Dark Green and S. Sunshine Dream. And the 13 accessions of Group II had more buds and leaves, and were smaller and more compact. The research results could provide a reference for evaluation and breeding of Spathiphyllum germplasm resources.

The study was aimed to cope with the rapid increase in demand for patchouli [Pogostemon cablin (Blanco) Benth.] and to solve the problems of lack of patchouli medicinal materials, germplasm degradation, confusion of germplasm sources, and vulnerability to diseases and pests. Callus, cluster buds and rooting seedling of patchouli were irradiated with a gradient dose of ⁶⁰Co-γ rays. The appearance and morphology of regenerated plants were observed, the mutated plants were screened, the agronomic traits and physiological and biochemical indicators were measured, and the content of pogostone and patchouli alcohol, the main volatile components, were determined by gas chromatography-mass spectrometry (GC-MS). The results showed that calluses and cluster buds were more sensitive to ⁶⁰Co-γ rays and had higher mortality rate, while rooting seedlings were more tolerant to ⁶⁰Co-γ rays and had lower mortality. The best way to breed mutagenesis is ⁶⁰Co-γ treated rooting seedlings with irradiation doses of 100 Gy with a mutagenesis rate of up to 10%. In this experiment, 29 patchouli variant plants were obtained, which were divided into seven morphological types, namely three-leaf whorls, heteromorphic leaves, deep-split leaves, narrow leaves, coiled leaves, undercoiled leaves and purple leaves. The contents of osmotic conditioning substances [soluble sugar, soluble protein and free proline (Pro)], antioxidant substances [malondialdehyde (MDA), peroxidase (POD), catalase (CAT)], pogostone and patchouli alcohol were compared and analyzed. According to the analysis results of the above determination indicators, 15 potential plants were finally screened, namely: stress-resistant plants with high effective components SY7 and ZY1; environmentally sensitive plants with high effective components SY15, SY18 and XY1; stress-resistant plants SY2, SY6, SY19, YY2, YY9 and XJY1; high active ingredient plants SY10 and SY17; “pogostone-type” patchouli plants SY3 and JY1. Among them, SY7 and ZY1 are new germplasms with double excellent characteristics, and the two “pogostone-type” patchouli plants have application value for solving the problems of the lack of authentic medicinal materials and the degradation of germplasm. In this study, patchouli variant plants bred by the ⁶⁰Co-γ ray irradiation mutagenesis method have the advantages of strong stress resistance and high active ingredients, which would provide mature methods and potential germplasm for patchouli mutagenesis breeding and new variety breeding.

In this paper, the seedlings of 27 inbred lines of bitter gourd with four leaves and one heart were used as materials. After pre-cultivated one day, the seedlings were subjected to 39 ℃ temperature stress. And the 27 germplasm resources were divided into three types: high heat resistance, medium heat resistance and heat sensitivity screened by the heat damage index (TDG) after 72 hours of high temperature stress. Among them, six inbred lines with different heat tolerance were selected to measure 12 morphological and physiological indexes subjected to 39 ℃ stress for 0 h and 48 h, respectively, including plant height (PH), stem diameter (SD), plant fresh matter (SFW) and dry matter (SDW) and leaf relative chlorophyll content (SPAD), electrical conductivity (REL), peroxidase activity (POD), catalase activity (CAT), superoxide dismutase activity (SOD), malondialdehyde content (MDA)), proline content (Pro) and soluble sugar content (SS). The comprehensive evaluation values were obtained by the principal component analysis of heat resistance coefficients (α) of 12 morphological and physiological indexes to evaluate heat resistance of the seedlings. The mathematical model of heat resistanc evaluation was established by the stepwise regression analysis to obtain the heat resistance evaluation index system of bitter gourd. According to TDG, among the 27 bitter gourd inbred lines, three were heat-resistant, 18 were medium-heat-resistant and six were heat-sensitive. A mathematical evaluation model of heat tolerance of bitter gourd was established using the stepwise regression equation, which is Y=–0.426+0.049X₁–0.011X₂–0.009X₃–0.018X₄. The established optimal regression equation was used to predict the heat resistance of the tested materials, and the predictive values were basically consistent with the comprehensive heat tolerance value. Therefore, the heat resistance coefficients of SFW (X₁), POD activity (X₂), CAT activity (X₃) and SS content (X₄) could rapidly and accurately estimate bitter gourd heat resistance and were suggested to be used as evaluation indexes for heat resistance of bitter gourd. In order to provide a basis for the breeding of new heat-resistant bitter gourd varieties in Hainan in summer season, the heat-resistant bitter gourd germplams were screened and a heat-resistant evaluation system was constructed.

Banana plant has the characters of fruiting in high position and of hanging in non-fixed orientation, which is not conducive to the flower removal, bud removal breaking, pesticide spraying, bagging and harvesting of banana fruit in production, and make it vulnerable to wind damage, causing lodging and breaking. In order to reduce the height position of banana fruit, make it hang fruit directionally, facilitate management, realize mechanized harvest and improve field management efficiency, a guide outlet was excavated at the lower position on one side of banana pseudostem by physical method to guide banana to fruit at the lower position and predetermined direction, and the differences in fruit characters between physically induced fruit and naturally formed fruit were studied. The results showed that opening the outlet by physical method could guide the banana fruit grow in a low position and a predetermined direction. The average fruit yield per plant was 21.47 kg (with a variation range of 11.5 kg to 36.15 kg), the average number of fruit fingers per plant was 187(with a variation range of 137 to 237), the average weight of single fruit finger was 120 g (with a variation range of 60 g to 190 g), the average length of fruit axis was 41.82 cm (with a variation range of 27.5 cm to 54.5 cm), the average length of outer arc of fruit finger was 17.88 cm (with a variation range of 13.4 cm to 21.1 cm), the average perimeter of fruit finger was 11.44 cm (with a variation range of 9.6 cm to 12.9 cm). Correlation and regression analysis showed that the fruit weight per plant, fruit axis length and fruit finger length were significantly negatively correlated with the time interval from opening outlet day to heading fruit day, respectively. Compared with the natural heading fruit, there was no significant difference in average fruit weight per plant, average total number of fruit fingers per plant and average number of fruit fingers per comb, there was no significant difference in the thickness of the fruit fingers and the curvature of the fruit fingers; but there was significant difference in average weight of single fruit and of fruit axis respectively; The length of fruit axis and the length of fruit finger and the spacing between fruit combs was significantly shortened respectively, the differences are all very significant.

Hainan is the southernmost litchi production area in China, but the problems of excessive nutrient input and soil degradation are serious, and the reasonable nutrient input standard is lacking. The study analyzed the current situation of litchi yield, nutrient management and soil fertility in the main producing areas of Hainan, based on the principle of nutrient balance, by quantifying the crop nutrient demand law and the reasonable nitrogen surplus level under the conditions, specifying the upper limit of litchi nutrient usage, proposing the reduction target of nitrogen, phosphorus and potassium nutrient inputs for litchi in Hainan, and analyzing the differences in nutrient management levels of different types of farmers and the impact on soil fertility. The upper limit of nitrogen, phosphorus and potassium dosage of litchi at different yield levels in Qiongshan region was 200 kg/hm², 100 kg/hm², and 260 kg/hm² (<10 t/hm²), 273 kg/hm², 136 kg/hm², 355 kg/hm² (10-20 t/hm²), 439 kg/hm², 220 kg/hm², 571 kg/hm² (20-42 t/hm²), respectively. The phenomenon of excessive fertilizer input of farmers was prominent, and the excess nutrient input was aggravated with the increase of management scale. 60%, 97% and 131% of small farmers, medium operators and large-scale operators were higher than the upper limit of nitrogen fertilizer input. Phosphorus input was 204%, 236%, 258% higher than the upper limit of input; potassium content was 70%, 101% and 119% higher than the upper limit. The fertilization intensity was also significantly higher than the national NPK fertilization level of 70.8%, 189.9%, 123.4%. The surplus of nitrogen, phosphorus and potassium in Hainan litchi orchard was 365 kg/hm², 377 kg/hm² and 542 kg/hm², respectively, and the nutrient use efficiency (NUE) was 34%, 21% and 27%, respectively. A lot of phosphorus was fixed and lost in the soil. There were significant differences in the nutrient management among different types of farmers. Only 1.2% of small farmers were in the range of high N output and low N surplus, while the middle and high operators were all in the range of high N surplus. Soil phosphorus accumulation and soil acidification were prominent problems in the litchi orchards, and 46% of the orchards had soil phosphorus content over 0.96 g/kg, which was at a relatively rich level. 94% of the orchards were acidic soil (pH 4.5-5.5), and 77% of the orchards had low soil quality index (IFI) comprehensive rating. For the current Hainan litchi nutrient inputs unreasonable and soil degradation, the quota system should be adopted and promoted as soon as possible, and the use efficiency of organic and chemical fertilizer should be greatly improved, so as to realize the sustainable development of litchi fruit industry.

In order to explore the effects of N, P and K fertilizers on the growth and nutrient uptake of areca nut seedlings and provide a scientific fertilizer application in field management, areca nut seedlings were used to conduct the “3414”fertilizer ratio in pots at the greenhouse. Fertilization significantly increased biomass and fertilizer utilization of areca nut seedlings. In balanced nitrogen, phosphorus and potassium fertilization, N and P fertilizers had the maximum utilization. Balanced nitrogen and potassium fertilization without phosphate fertilizer, K fertilizers had the maximum utilization. The N content was the main factor affecting the stem and leaf biomass, while the P content was the main factor affecting root biomass. Correlation and path analysis indicated that N and P could synergistically improve the growth of areca nut seedlings, but they were affected by the application of K fertilizer. However, N, P and K fertilizers could reach balance and synergy to improve the growth of seedlings. In conclusion, N, P and K fertilizers in a rational proportion was beneficial for the nutrient uptake and utilization of areca nut seedlings, and N∶P∶K=2∶2∶2 (T₆) was the most suitable fertilization ratio.

In order to clarify the alleviating effect of heterologous double-root on coffee continuous cropping obstacle, the soil of the continuous cropping obstacle garden of coffee was used to cultivate Caffea liberica, No. 1 and C. canephora, Reyan No. 1 heterologous double-root grafting coffee seedling. The mechanism of heterologous double-root alleviating continuous cropping obstacle was clarified through different root separation ways, and the differences and synergies of heterologous double-root in alleviating continuous cropping obstacle were discussed. Compared with non-rhizosphere soil, the seedling quality index and plant biomass of heterologous double-root coffee or homologous double-root coffee decreased significantly after culturing in rhizosphere soil. After non-rhizosphere soil culture, there were no significant differences in the seedling quality index or plant biomass between heterologous double-root coffee and homologous double-root coffee. The seedling quality index, root biomass of C. liberica and C. canephora, and total plant biomass of heterologous double-root coffee were significantly higher than those of homogenous double-root coffee after rhizosphere soil culture. Continuous cropping obstacle inhibited the growth of coffee, but had more effect on homologous double-root coffee. Heterogenous double-root coffee alleviated the growth obstacle of continuous-cropping coffee by C. liberica roots. The seedlings quality of the heterologous double-root coffee separated root by nylon net was better than that of root undivided or separated root by double pot under continuous cropping, and the root growth of C. canephora was the best in nylon net separation. Root allelochemicals of C. liberica promoted the root growth of C. canephora. There was no significant difference in the seedlings quality of heterologous double-root coffee between root undivided and separated root by double pot, and the C. liberica root growth of root undivided was worse than that of double pot separation. The root growth of C. canephora inhibited the root growth of C. liberica when the heterologous double-root were in contact with each other, but this inhibition was not related to the allelopathic substances in the C. canephora rhizosphere. The root growth of C. liberica had no significant difference in nylon net separation and double pot separation. There was no effect on the root growth of C. liberica with or without the allelopathic substances. of C. canephora. The root system of C. liberica alleviated the continuous cropping obstacle by reducing the inhibition of allelopathic environment and promoting the root growth of C. canephora by its allelopathic substances. The results would provide a theoretical basis for the application of heterologous double-root grafting in the field.

Reasonable planting density and depth are the common cultivation techniques to increase sugarcane yield per unit area. However, the effect on sugarcane lodging is often neglected when the yield is increased. Sugarcane variety Zhongtang 3 was used as the experimental material to determine the effect of different planting density and depth on the yield and lodging. Four planting density 3.0, 4.5, 6.0 and 7.5 buds/m² and two planting depth of shallow planting (30 cm) and deep planting (40 cm) were designed in the experiment. The agronomic characters, lodging related index (root lodging and stalk lodging) and yield of sugarcane were measured. The results showed that as the growth period of sugarcane continued to advance, the safety factor of sugarcane root and stem gradually decreased, and the risk of root lodging and stem lodging of sugarcane was higher at 180 days after planting, which was in a sensitive period. When the planting density increased from 3 buds/m² to 6 buds/m², sugar yield (+32%) and yield (+36%) of sugarcane were significantly increased, and the stem lodging resistance of sugarcane was also increased. However, when the planting density was further increased to 7.5 buds/m², the sugar yield and yield did not increase significantly, but the risk of root lodging was increased. Compared with planting depth of 30 cm, planting depth of 40 cm had a tendency to increase sugar yield (+2.8%) and yield (+4.8%), although there was no significant difference between them. Therefore, considering sugar yield, yield and lodging resistance of sugarcane, we believe that planting depth of 40 cm and planting density of 6 buds/m² can improve lodging resistance of sugarcane while ensuring yield and sugar yield.

The effects of different fertilizer combinations on the growth and nutrition of Camellia oleifera were studied to select the fertilizer combination that is conducive to the growth of C. oleifera. Ten-year-old common C. oleifera Cenruan 3 was used as the material. Ten experimental treatments with different N∶P∶K ratio and dosage, and different dosage of organic fertilizer were set. The physiological indexes of fruit traits, leaf traits and nutrition of C. oleifera at different growth stages were measured, and the analysis of variance, multiple comparisons and correlation analysis were performed. The results show that 0.5 kg N∶P∶K (20∶8∶17) +5 kg organic fertilizer+0.25 kg medium elements water-soluble fertilizer (Ca+Mg≥10.0%) had the best growth effect on C. oleifera. This fertilizer combination could effectively increase the fruit size, leaf area, net photosynthetic rate, transpiration rate and contents of nitrogen, phosphorus, potassium, calcium and magnesium in trees, which is conducive to the storage and distribution of tree nutrition. In conclusion, 0.5 kg compound fertilizer N∶P∶K=2∶1∶2 and 5 kg organic fertilizer applied together twice one year in the Spring and Autumn had a better effect on the growth and nutrition of C. oleifera.

The study was aimed to explore the effects of applying different organic fertilizers on the yield, quality, soil fertility of sweet potato. Five different organic fertilizer treatments with no fertilization as the control were set up and sweet potato variety Qianshu 6 was used. The results showed that the application of organic fertilizer could effectively promote the growth of sweet potato vines and the expansion of root tubers. The yield of Shangcanli biological organic fertilizer (T₄) was the highest, which was 19.9% higher than that of the control. The effects of different organic fertilizers on the nutritional quality of sweet potato were different, but the accumulation of dry matter was not obvious. In addition, planting sweet potato significantly reduces the nutrient content of soil, while applying different organic fertilizers could supplement part of the nutrient requirements of sweet potato, but had no significant impact on soil pH value. Organic fertilization significantly increased the contents of soil microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN). Organic fertilization significantly increased the activities of urease (URE), acid phosphatase (ACP), N-acetylglucosidase (NAG) and cellobiase (CBH), but significantly decreased the activities of nitrate reductase (NR) and-Glucosidase (BG), while did not significantly affected the activityof other enzymes. Correlation analysis showed that the effects of different components of organic fertilizer on the yield and quality of sweet potato root tubers were quite different. The pH value of fertilizer and the amount of organic matter input mainly affected the quality of root tubers, while the amount of pure nitrogen input was closely related to the yield and quality of root tubers. The physical and chemical properties of soil were mainly affected by the pH value of organic fertilizer, the input amount of organic matter and pure nitrogen, but had little correlation with the input amount of pure phosphorus and pure potassium. The correlation between organic fertilizer and soil MBC, soil URE, ACP, NR, PPO and LAP was stronger than that of soil microbial biomass nitrogen (MBN), N-acetylglucosidase (NAG), cellobiase (CBH) and polyphenol oxidase (PPO). Different organic fertilizers promoted the growth of sweet potato, increased the yield of sweet potato, increased the nutrient content of soil, and changed the microbial environment of soil to a certain extent. Therefore, the correlation analysis results of indicators could provide references for sweet potato production.