Spatial and Temporal Variability of Soil Organic Matters in Se-rich Areas of Hainan Island in Recent 30 Years

[Objectives] The aim was to reveal the distribution of soil organic matter content in cultivated land in the Se-rich areas of Hainan in 1980and 2010, so as to provide reference for the study on the evolution of soil organic matter content.[Methods] With the combination of field investigation with indoor analysis, the characteristics of organic matter content in the Se-rich areas of Hainan in 1980 and 2010 was revealed by means of spatial analysis, and the differences were analyzed.[Results] In the last 30 years, the proportion of 20-30 g/kg of soil organic matter content in the Se-rich areas of Hainan was reduced, but the content of soil organic matter in the area generally increased. The average value of the content of organic matter in the area was increased from 25.3 g/kg in the 1980s to 28.1 g/kg, but its spatial distribution was uneven.[Conclusions] The farmers should be guided to change the fertilization structure, and attention should be paid to the application of organic fertilizer, so as to improve the soil organic matter content.

Distribution of Nutrient Content in Soil and Leaves of Adult Areca catechu Trees

The annual dynamic changes of nutrient content in soil and leaves of adult Areca catechu trees in the A.catechu producing area Tunchang were studied by fixed point observation method to provide the scientific basis for the rational fertilization of A.catechu.The results showed that the soil of the A.catechu plantation was weakly acidic on the whole,and soil pH was 5.53.Soil phosphorus content was extremely low,only 5.46 mg/kg.Nitrogen content in A.catechu leaves was the highest( up to 20.24 g/kg),while phosphorus content was the lowest( only 0.31 g/kg).The differences in nutrient content were related to the characteristics of nutrient demand.There was a difference in nutrient content of A.catechu leaves during the annual growth period.Because the maximum nutrient requirement period of A.catechu trees was from April to September,the important fertilization period of A.catechu trees was also from April to September.

Distribution of Soil Nutrients in Se-rich Areas of Hainan Island

[Objectives] The aim was to reveal the distribution of soil nutrients in Se-rich area of Hainan and to clarify their specific contents, so as to provide references for the development of Se-rich area agriculture in Hainan.[Methods] With the se-rich area in Hainan as the object, field investigation and indoor analysis were combined to elucidate the nutrient status of cultivated soil in the area and analyze its nutrient distribution.[Results] The soil in the se-rich area in Hainan province was generally acidic with the average soil pH value of 5.0. The difference in soil pH between different landforms and different altitudes was not significant, ranging from 4.9 to 5.3. Soil available P and available K contents were low to intermediate, and the soil available N content was moderate. The farming system, chemical fertilizer application structure and meteorological factors were the main causes of the distribution of soil nutrient elements. The soil exchangeable calcium and magnesium content was rich, and the distribution of trace elements in the arable soil of different terrains and elevations was closely related to the distribution of soil parent material in the region. The increase of soil organic matter content in arable land could be achieved by increasing the application of organic fertilizer and guiding the farmers to enhance the application of straws to fields.[Conclusions] The application of soil N, P and K fertilizers should be combined with the application of soil organic fertilizers to improve the soil fertility of cultivated land.

Effect of Internal Ethylene and 1-methylcyclopropene on Ripening of Papaya Fruit(Carica papaya L.)

With papaya fruit （ Carica papaya ） as an experimental material, variations of its physiological indices were investigated through hypobaric hypoxia （HH, 10 kPa, 1.5 kPa O 2） treatment followed by fumigation with 1-methylcyclopropene （1-MCP）, so as to discuss the effect of interaction between 1-MCP and internal ethylene on ripening of papaya fruit during postharvest storage. The results indicated that HH treatment significantly reduced internal ethylene concentration （IEC） by 57.6%. However, there were no remarkable differences in other physiological indices between various treatments and control （CK）. The 1-MCP and HH＋1-MCP treatments could significant postpone the softening process and color change of papaya fruit. The two treatments achieved the effects of significantly inhibiting the occurrence of fruit disease and the increase of pericarp cell membrane permeability, effectively delaying the variation of soluble solid and Vc contents, and better maintaining soluble solid and Vc contents in fruit, thereby better keeping nutritional substances and flavor quality in fruit in later storage period and prolonging the storage time of fruit.