Evaluation of growth and fruiting ability of some clones of Macadamia intergrifolia Maiden - Betche in Ba Vi, Hanoi

However, the research results of the topic as well as previous research results have shown the relationship between the decrease in N, P, K content during flowering and fruit drop. Research results on fertilization for Macadamia in China have shown that Macadamia is very sensitive to the content of N, P, K, so when fertilizing Macadamia, it is best to apply small amounts and divide them into many stages to increase the absorption capacity of the tree without causing shock to the tree. Stage 1, fertilization should be carried out before flowering (February). During this period, nitrogen (N) should be mainly applied. Stage 2, after the tree flowers - this is the time when the mineral content in the tree decreases due to accumulation for flowering, fertilizing during this time will contribute to accumulating nutrients for fruit formation and growth. Stage 3 should be applied before fruit harvest (around July-August). The fourth fertilization should be done after harvesting the fruit (October) to supplement mineral nutrients for the plant to continue growing for the next crop. The fertilizer ratio should be based on the soil pH but pay attention to increasing the N and K content compared to P.

d) In addition, Macadamia is a tree with shallow roots and a large canopy, so it is very easy to break during strong storms. Therefore, pruning is an important task, both increasing the canopy area, thereby increasing the number of flowers, and adjusting the canopy to minimize breakage.

Chapter 5

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CONCLUSION, PROBLEMS AND RECOMMENDATIONS

5.1. Conclusion

5.1.1. Growth of Macadamia

- Growth of seedlings in the nursery is relatively uniform. The general trend is to gradually decrease the growth rate of root diameter from the 7th and 8th months while height growth continues.

- In general, the growth of the tested lines planted in Cankyna grew better than that in Cam Quy despite the same silvicultural treatments (the ratio X 1 / X 2 was always less than 1 although the trees in Cam Quy were planted 1 year earlier). The preliminary cause was assessed to be due to differences in some soil characteristics (soil layer thickness, mineral nutrient content in the soil in Canhkyna was higher than in Cam Quy). Line 842 had the biggest difference between the two areas. Lines 816, 842,

849, 788, OC were lines with better growth ability than other lines at both research locations.

5.1.2. Flowering ability

- Macadamia grown in Ba Vi flowers in March, the flowering time can vary depending on the variety but usually does not exceed 10 days. The duration of the flower varies depending on the variety, from 4 days (NG8 variety) to 30 days (849 variety). The flowering time and flower duration will greatly affect the fruit set rate due to the influence of weather factors.

- Line 842 has the highest number of inflorescences, exceeding 49.88% compared to the average number of inflorescences of the lines. Line H2 has the lowest number of inflorescences (51.17% less than the average number of inflorescences of the lines). Number of florets on a flower

also varies by line ranging from 175 florets (line H2) to 200 florets (line 816 and line 849).

- Initially, it was determined that there is a relationship between the flowering ability of Macadamia and some growth indicators and some separate ecological factors. This is the basis for predicting the amount of flowers and fruits.

5.1.3. Fruit setting ability

- Macadamia fruit develops in an average time of about 140 to 160 days depending on the variety. Fruit size changes very quickly in the early stages (about 45 days from the date of fruit formation) and then slows down. Fruit size varies depending on the variety but is usually about 2.8cm to 3.5cm on average.

- The ability to set fruit depends largely on the weather as well as the physiological characteristics of the plant. The fruit set rate from the flower buds has a wide range of about 0.002% to 0.680% corresponding to different lines. This is an average rate compared to the original in Australia and in Hawaii and is equal to some lines grown in China.

- Lines 842, 816, 849, OC, 741 are lines with different numbers of flowers but all have the largest amount of mature fruit.

5.1.4. Fluctuations in total N, P, K content in soil

- The total N, P, K content in the soil used to grow Macadamia trees varies according to soil depth. In general, the topsoil layer (0-20cm) has a higher total N, P, K content than the subsoil layer (20-50cm).

- There is a difference between the macadamia soil in 2003 and the macadamia soil in 2006. The soil under the macadamia planting area in 2003 has higher N and K content than the soil under the macadamia planting area in 2006, but the P content is lower.

- Compared with the control, the change in total N, P, K content in Macadamia soil did not show a clear pattern.

5.1.5. Changes in total N, P, K content in leaves

- There are differences in total N, P, K content among the studied lines, in which total N content accounts for the highest proportion.

- The N, P, K content in leaves before and after flowering changed significantly.

N content fluctuated the most while P content fluctuated the least.

5.1.6. Prediction of potential flower and fruit yield

Lines 842, 816, 849, OC and 741 proved to be lines with good growth ability, high fruit set rate, and large fruit size. These are lines that are considered to have development potential. The results of predicting potential flowers and fruits in the next 3 years show that the average fruit quantity will reach from 870 fruits (line 741) to 1170 fruits (line 842).

5.2. Main existence

- The research results are only based on short-term observations and records, so the age of maturity of flowers and fruits of the research subjects cannot be concluded.

- There are no conditions to arrange controlled experiments to study the influence of ecological factors on growth and especially the very high rate of young fruit drop of Macadamia.

- There are no conditions to analyze the content of some minerals in flowers and fruits to have accurate and objective assessments of the role of mineral nutrition in flowering and fruiting of Macadamia along with the mineral content in leaves.

- The prediction is based only on some simple ecological factors while there are many factors affecting the flowering and fruiting ability of Macadamia that have not been studied.

5.3. Recommendations

- If possible, control experiments should be conducted from the nursery stage until experimental planting.

- It is necessary to analyze the mineral nutritional content in Macadamia parts at different stages to clarify whether the high fruit drop rate is due to the nutritional regime or not. If so, solutions will be found to protect flowers and fruits and increase productivity.

- It is necessary to continue to improve the forecasting work. Find ecological indicators to make the forecasting more accurate. This is a very meaningful work in being proactive about productivity, output as well as market prices.

INDEX

SIDE COVER

THANK YOU… I

TABLE OF CONTENTS… II

LIST OF TABLES… V

LIST OF FIGURES AND CHARTS VII

PROBLEM STATEMENT 1

Chapter 1: OVERVIEW OF RESEARCH PROBLEM 3

1.1. In the world 3

1.1.1. Studies on the growth of Macadamia 3

1.1.2. Studies on flowering, fruiting and fruit quality 4

1.1.3. Studies on the distribution and mineral content in plant parts; their effects on growth and flowering and fruiting ability 6

1.2. In Vietnam 8

1.2.1. Studies on growth 8

1.2.2. Studies on flowering and fruiting ability 9

1.2.3. Studies on the distribution and mineral content in plant parts; their effects on growth and flowering and fruiting ability 10

Chapter 2 OBJECTIVES, LIMITATIONS, CONTENT AND METHODS OF RESEARCH 11

2.1. Research objectives 11

2.1.1. Theoretical aspect 11

2.1.2. In practice 11

2.2. Research limitations 11

2.3. Research content 11

2.3.1. Growth ability 11

2.3.2. Ability to flower and fruit 11

2.3.3. Some factors affecting growth, flowering and fruiting 12

2.3.4. Predicting potential flowering and fruiting 12

2.3.5. Some suggestions 12

2.4. Research methods 12

2.4.1. Methodological perspective 12

2.4.2. Method of collecting documents 13

2.4.3. Internal treatment method 17

2.4.4. Research diagram 20

Chapter 3 CHARACTERISTICS OF CONDITIONS OF THE STUDY AREA 21

3.1. Natural conditions 21

3.1.1. Geographical location 21

3.1.2. Terrain 21

3.1.3. Hydro-climate 21

3.1.4. Geology and soil 22

3.1.5. Flora 22

3.2. Socio-economic conditions 23

Chapter 4 RESEARCH RESULTS AND DISCUSSION 25

4.1. Some growth characteristics 25

4.1.1. Growth ability of seedlings in the nursery 25

4.1.2. Growth of experimental plants 26

4.2. Ability to flower and fruit 33

4.2.1. Some characteristics of flowers and fruits 33

4.2.2. Ability to flower and form fruit 36

4.3. Some ecological factors affecting growth and flowering ability ..48

4.3.1. Temperature 48

4.3.2. Potential rainfall and evaporation 51

4.3.3. Lighting mode 52

4.3.4. Some chemical characteristics of soil 55

4.3.5. NPK content in Macadamia leaves 61

4.4. Forecasting potential fruit yield 68

4.5. Some suggestions 69

Chapter 5 CONCLUSION, PROBLEMS AND RECOMMENDATIONS 72

5.1. Conclusion 72

5.1.1. Growth of Macadamia 72

5.1.2. Flowering ability 72

5.1.3. Fruiting ability 73

5.1.4. Fluctuations in total N, P, K content in soil 73

5.1.5. Fluctuations in total N, P, K content in leaves 74

5.1.6. Prediction of potential flower and fruit yield 74

5.2. Mainly exists 74

5.3. Recommendation 74

Evaluation of growth and fruiting ability of some clones of Macadamia intergrifolia Maiden - Betche in Ba Vi, Hanoi - 10

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