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Bui Thị Lan Hương
“The investigation of the population composition of the nematodes and the effective survey of a number of nematicide with the effect to prevent and eliminate the nematodes that is harmful to the cactus grown at the Dam Sen cactus collection garden”
has been carried out at the Cactus Collection Garden in the precinct of the Dam Sen Cultural Park, belongs to Phu Tho Tourist Company, Saigon Tourist Corporation, Ho Chi Minh City in the period from April 2002 to August 2003. The completion and report of the result of this was in February 2004 at the Agriculture and Forestry College of Ho Chi Minh City.
Through the investigation of the composition, a number of nematodes that have caused harm on the cactus at the Dam Sen Cactus Collection Garden following the investigation time in the year, the different cactus growing methods, growing through graft trunk and growing directly in the ground, the types of cactus to be the different graft feet, the different types of cactus, the different cactus growing environments, growing in the pots and growing on the ground, the different point of time after the growing: 25 days after growing, 55 days after growing and 75 days after growing.
We have found that there are 4 kinds of the nematodes appeared on the cactus at the Dam Sen Cactus Collection Garden which consists of the Meloidogyne, Helicotylenchus, Pratylenchus, Tylenchorhynchus to be classified in the 4 families of the Tylenchidae set, in which, the kind of Meloidogyne is the most dangerous and important object as of its very high its frequency of occurrence and the absolute density number.
The density number of the Meloidogyne nematodes has no large variation through the investigation period of time.
The density number of the Meloidogyne nematodes at the growing plant through grafting foot is less than the ground planting.
The density number of the Meloidogyne nematodes at the Thanh Long cactus used as the grafting foot is less than at the six sided prickled cactus.
The density number of the Meloidogyne nematodes at the Kim Ho cactus and the Moc Cau cactus is more than the cactus grown on the Tru Khe.
The density number of the Meloidogyne nematodes in the pot growing environment is lower than ground growing environment.
The secret number of the Meloidogyne nematodes at the point of time of 25 days after planting is not tall yet and is different from the point of time of 75 days after planting.
Surveying the effect of a number of nematicide that have the action on the prevention and elimination of the nematodes that is harmful to the cactus to find out the kind of medicine of the most effective action. As the experimental result has shown that the Vimoca 20ND is the highest effect in the nematodes prevention and elimination
Che Thi Da
Robusta clonal selection for high yield, large bean size and leaf rust resistance in Daklak province.
In the years of bumping area extention, most of planting material came from unselected seeds that resulted in high variation of agronomic trials limiting the yield potention as well as the uniformity of bean size. Survey in various commercial plantations indicated that there were around 10 -15% percent of trees with very low yield, small bean size, heavy leaf rust infested. In general, coffee bean for export has rather small bean size. Bean grading showed that the average weigh of 100 beans was about 13 - 14 grams and percentage of grade I 30 - 40%.
Those above - mentioned weaknesses of Vietnamese robusta coffee justify for the replacing of existing poor trees in current commercial coffee plantations by selected clones.
The research has been carried out in Daklak Province since 1994 as a second phase selection to further: improve Robusta clones which are needed for the progam of increasing the yield and bean size.
Based on annual investigation of mother trees existing commercial gardents as well as their vegetative replicates in working collection, a number of clones has been introduced into 3 comparative clonal trials since 1996.
The common trial design is one-facter Randomized Complete Block with 4 replications.
The main selection criteria include: yield, bean weight and size (weight of 100 beans and percentage of beans retained on sieve No 16) conversion ratio (berry/bean) and leaf rust resistance, among which bean size and weight are focused.
From the first trial result, five clones were selected after three harvests, and seven clones were selected after two harvests from the second trial result, result of the third trial estimated again selected clones in two trials (N0 1 + N0 2).
Finally, the best 11 clones were selected after 2-3 harvests with the following characteristics: average yield 2.7 - 3 tons of green bean/ha, percentage of beans retained on sieve No 16: >65%, weight of 100 beaan: >18g, the berry/ bean ratio: 4.5 and index of leaf rust: < 2%.
They are the basic plant materials to introduce them to the coffee farmers to graft on bad trees in coffee field in Daklak province.
These clones have been suggested for multilocate trials in coming years to obtain selected clones adaped to each cultivation region.
Co Khac Son
“The effects of dolomite application on soil fertility improvement and nutrient supply in a reddish brown soil (Rhodic Ferralsol) of the Eastern region of South Vietnam”
was carried out at the Hung Loc Agricultural Research Center located at Hung Thinh village, Thong Nhat district, Dong Nai province from August 2001 to April 2002. The study covered two issues:
- The effect of dolomite application on some soil properties was carried out at the green house of Institute of Agricultural Science of South Viet Nam. The results indicated that dolomite application decreased exchangeable Al concentration, increases pH, CEC and percentage of Ca2+ and Mg2+ saturation.
- The effectiveness of dolomite application on maize yield was carried out at the experimental field of Hung Loc center. Grain yield of maize increased 7.9 to 19.0% from the control as the application rates increased from 500 – 1500 kg dolomite/ha. As consequence, income increased from 419,000 – 845,000 VND/ha/cropping season.
Dao Lam Huong
Researching some techniques of cocoa vegetative propagationby rooted cuttings
The research on several techniques of vegetative propagation of cocoa by rooted cuttings was conducted at The Western Highlands Agro - Forestry Science and Technique Institute from March to December 2000.
The research consisted of 7 experiments which were arranged factorially in a completely block design with 4 replications and 3 experiments which were arranged with completely random design with 4 replications.
The objective of the research is to study the various factors affecting the rooting process of cuttings, such as: hormones and concentration, rooting medium, seasons of cutting, type of rooted cuttings and their ages, techniques of treating rooted cuttings by trimming the leaves and methods of rooted cuttings (by transplanting the cuttings into polythene bags and rooting medium).
The objective of the research is also to evaluate the hardening of rooted cuttings after their transplantation and growth.
After 5 weeks we started transplanting the cuttings and conducting observation. The results showed that with the solution of IBA of 6000 ppm the success rate was the highest (70%) and the number of roots per cutting was the most. The use of the IBA and NAA solution of 4000 - 6000 ppm was not as effective as the use of IBA with 6000 ppm. The semi- hardwood cuttings having 1 - 2 nodes with 1 - 2 leaves of stem that were trimmed by three - quarters reached the fairly high rate.
Ten clones were found to vary considerably in their rooting ability. Six of those were excellent roots while other four were poor even though they were treated with hormones. The rooting rate of the orthotropic shoots was higher than that of plagiotropic ones.
The method of hardening the rooted cuttings after transplantation is very important to increase the vitality of rooted cuttings.
In Daklak, the best seasons for cutting are May and July.
Dinh Xuan Truong
Study on the ability of some rubber clones in response to ethephon latex stimulant at Lai Khe
A study was carried out to investigate the ability in response to ethephon latex stimulant of several rubber clones which have been newly selected in Vietnam. Those promising clones were listed in Table I and Table II of the Clonal Combination Recommendation of Vietnam General Rubber Corporation for 2002 - 2005.
This study contributed to determine the reasonable stimulated tapping systems for those new clones in the aim of developing their yield potential and improving the economic effective of rubber trees.
Two experiments have been laid out at Lai Khe Rubber Experiment Station, Rubber Research Institute of Vietnam.
The first experiment (CTLK90 Plot), which was on the rubber trees in the sixth year of tapping, consisted of two treatments: stimulated with ethephon 2.5% 4 rounds/year and control non stimulated. These two treatments were set up on 6 clones, namely RRIV 2, RRIV 3, RRIV 4, RRIV 5, GT 1 and PB 235. The split plot design was used for this experiment.
The second experiment (XTLK1/95 Plot) which was on the rubber trees in the first year of tapping, consisted of four treatments: Stimulated with ethephon 2.5% 2 rounds, 4 rounds, 6 rounds per year and control non stimulated. These four treatments were set up on 3 clones: RRIV 4, RRIV 5 and PB 235. The randomised complete block design was used for this experiment.
The experimental trees were tapped on a half spiral (1/2S) cut, in every 3 days (d/3)
After one year, the findings were:
+ Response to stimulation of those clones from high to low followed this order: RRIV 2, RRIV 3, RRIV 4, PB 235, GT 1, RRIV 5.
+ The highest response to stimulation was found on clone RRIV 2, as its yearly average yield of gram of dry rubber per tapping per tree (g/t/t) was 152.4% compared to control non stimulated, and the yield in stimulated month could exceed 200% compared to control non stimulated.
+ The lowest response to stimulation was found on clone RRIV 5 , as its yearly averaged yield (g/t/t) was only from 100.1% to 113.4% compared to control non stimulated .
+ It appeared that clone RRIV 4 was suitable to stimulated 4 rounds per year, whereas clones RRIV 5 and PB 235 were suitable to stimulated 2 rounds per year.
+ After one year of stimulation, it should be noted that no adverse effects on physiological status and the dryness of the rubber trees.
Doan The Thuy
“Exploration and evaluation some of varietal samples in sugarcane stock at Sugarcane Research Institute”
was performed from May 1997 to Dec. 2001. In details, seven varietal samples including Colombia 1, Colombia 2, Colombia 3, ROC9, ROC17, QDT, VM14 were evaluated in plant crop and two ratoons (May 1997 – Jan. 2000) and eight varietal samples including ROC20, ROC18, QÑ15, VD86-368, Phil85-83, MC, VMC, Uthong 2 were evaluated in plant crop and the first ratoon (Oct. 1999 – Dec. 2001). The experiments were designed consecutively by varietal samples on relatively identical area, 1 – 2 rows of 5 meter long per varietal sample, 1.2-meter row distance, 4 – 5 three-bud cuttings per meter long.
Some basic features of botany, growth, yield, quality and resistant ability of varietal samples above were identified. Colombia 3, ROC9, QDT, ROC20, QÑ15, VD86-368, Phil85-83 and Uthong 2 could be tested in different ecological zones. The varietal samples for breeding program consisted of Colombia 1, Colombia 3, ROC9, QDT, ROC20, QÑ15, VD86-368, Phil85-83 and Uthong 2. These varietal samples have some good features such as Colombia 1, QDT, VM14 and ROC20 with good germinating; Phil85-83 with strong tillering; Uthong 2 with large diameter and high sugar content; VD86-368 with strong growth; Colombia 3, QD15 and VD86-368 with high density of millable stalks; Colombia 3 with high and stable yield; ROC9, QDT, QD15 and VD86-368 with high yield and quality.
Le Pham Hoa
“ Studies on the floral induction methods and fruit setting improvement for some longan cultivars (Dimocarpus longan Lour.) in Phu Giao district, Binh Duong province.”
Four experiments were carried out at Trang Nong Farm, Tan Hiep village, Phu Giao district, Binh Duong province.
Experiment 1: Studies on the floral induction methods for floral induction of longan cultivars. This experiment includes 5 treatments, namely: 1) Control, 2) Girdling around main branches, 3) applying KClO3 at the rate of 30g per meter of the canopy diameter , 4) Girdling and applying KClO3 30g, 5) Spraying RHB+RHX on leaves.
The results showed that the treatment of spraying leaf fertilizers of RHB+RHX gave the best, 92.2 and 98.2 inflorescences per tree for Tieu da bo and Tieu la bau cultivars, spraying leaf fertilizers of RHB+RHX increased the length of the inflorescences.
Experiment 2: Study on the amount of KClO3 applied per tree. This experiment has four treaments, namely: 1) Control, 2) 30g, 3) 40g, 4) 50g KClO3 per meter of the canopy diameter. The treatment 50g gave the best result, 97.4 and 103.3 inflorescences per tree for Tieu da bo and Tieu labau cultivars. while the control treatment had not any inflorescences.
Experiment 3: Study on the effects of Gibberellin (GA3) and Naphthalene acetic acid (NAA) on fruit setting. The experiment has 7 treatments: 1) Control, NAA15ppm, NAA 50 ppm, GA3 15ppm, GA3 50ppm, GA315ppm + NAA 15ppm, GA3 50 ppm + NAA15ppm.
The result indicated that Gibberellin (GA3) and Naphthalene acetic acid (NAA) make the fruit setting increase. Flowers emerged more concentrately for both longan cultivars. Treatment (GA315 ppm + NAA15ppm), treatment (GA3 15ppm), treatment (GA3 50ppm) make the fruit setting increase the fruit setting per inflorescence significantly at the probability of 1% comparing to NAA 50ppm and control treatments.
Experiment 4: Study on the effect of some leaf fertilizers on the fruit setting, yield and quality of Tieu da bo cultivars. This experiment included five treatments: 1) HPC-B97, 2) Thien Nong, 3) Progibb, 4) FFC, and 5) control. The results showed that the fruit seting in the treament of HPC-B97, Thien Nong, Progibb and FFC increased significantly about two fold comparing to the control treatment. The weights of fruit are 12.9g, 12.5g, 11.6g, 12.4g and 8.1g for treatments of HPC-B97, Thien Nong, Progibb, FFC and control, respectively. Statistical analysis of yield showed that there were significant differences among treaments. Leaf fertilizers increased the Brix of juice from 20.6% (in the control treatment) to 23.9% (in the treatment of HPC-B97). The edible portion is non significant difference among treatments.
Le Thi Thanh Phuong
“Extracting biologically active compounds from neem seed kernels (Azadirachta indica A. Juss) and investigating their effects on the rice moth (Corcyra cephalonica St.)”
was carried out at the Institute of Tropical Biology in Thu Duc, Ho Chi Minh City from August 2002 to August 2003. Four neem seed kernel extracts (ethanol, hexane, methanol and aqueous extracts) were prepared and screened for their effects in comparision with Indian neem oil on rice moth.
The experiments were performed in the completely randomized design with three replications under laboratory conditions. The statistical analysis was based on Analysis of Variance (ANOVA) and Duncan’s Multiple Range Test. LD50 values were obtained from Probit Analysis.
The results of HPLC analysis showed that azadirachtin contents in the methanolic, ethanolic, aqueous and hexane neem seed kernel extracts and Indian neem oil were respectively 800, 780, 510, 30 and 90,0 ppm. It was seen that all these neem products affected C. cephalonica as antifeedant, insecticidal, development deterring and fecundity inhibiting agents.
- Antifeedant effect: The methanolic extract strongly deterred feeding by larvae of rice moth form the first to the fifth instars with antifeedant coefficients 180,7; 159,9; 150,5; 148,7 and 102,8, respectively. Whereas the hexane extract had the lowest antifeedant activity with antifeedant coefficients of larvae form the first to the fifth instars respectively 106,6; 100,3; 86,7; 85,2 and 76,0 %.
- Insecticidal effect: Fumigation with these extracts caused mortality of rice moth in various development stages. All extracts had the highest toxicity against the fifth instar larvae and adults with LD50 values respectively 817,9 and 608,6
Truong Thi Ngoc Loan
“ Applying land evaluation method of FAO for conversion of some major plants at Laâm Haø district, Laâm Ñoàng province”
was carried out at Laâm Haø from August 2002 to August 2003. The results of this study were as following:
- Natural environment: Laâm Haø district with monsoon tropical climate was relatively appropriate to develop of many long – term industrial crops such as coffee, tea and mulberry plants. However, shortage of water in dry season in this area had significantly affected to agricultural production. Investigating results showed that the rate of population increasing, specially migrate population increasing was very high. Ninety percent of total labours was to service in the domain of agriculture.
- Social economical conditions: In recent years, the economical development has rapidly increased whereas infra-structural development has relatively been slow. The foreigner investment has been limited.
- Soil characteristics: Based on the soil map of Laâm Haø performed by Sub – National Institute of Agriculture Planning and Projection, there have been 6 soil groups and 12 soil mapping units as following: 118.190 ha of ferralsols (74,44%), 16.138 ha of gleysols (10,16%), 12.674 ha of humic ferralsols (7,98%), 4.232 ha of fluvisols (2,67%), 3.342 ha of acrisols (2,11%), 2.764 ha of luvisols (1,74%).
- Land characteristics: By overlaying the factor maps such as soil group, slope and so on, a land unit map was established at scale of 1/50.000. There were 48 land mapping units in this area.
- Present land use and land use systems for agriculture: The surveying results showed that there were 6 major kinds of land use, 20 of land use types with 79 land use systems and 64 land use systems were proprosed for agriculture production. The agricultural area was 48.491,89 ha that was approximatively 30,34 percent of total area. The area of food, vegetable, short – term industrial, long – term industrial, fruit and other perennial crops were respectively 6.988 ha (14,4%), 1.544 ha (3,18%), 1.193 ha (2,46%), 37.729 ha (77,8%), 465 ha (0,96%) and 73 ha (0,15%).
- Land suitability: There were 53.474 ha suitable for agricultural production.
- Propose: From above results some propositions were as following:
Conversion of 4.564 ha of coffee cultivated on unsuitable land in to cutting tea (1.545 ha), hybrid mulberry (165 ha), fruit plant (1.035 ha) and forest trees (1.719 ha) .
Otherwise, in oder to improve both quantity and quality of products, it should be converse 5.000 ha of robusta coffee to arabica coffee. 175 ha of tea growed by seed should be converted to tea growed by cutting, 960 ha of mulberry to hybrid mulberry.
However, to promote the process of conversion rapidly and effectively, it is necessary to support other solutions such as applying modern technologies, policies of land development, credit and tax. Besides, development of post – harvested processing technologies and product promotion programs were also concerned.
Nguyen Thi Thanh Thao
“Investigate the effects of Cd on growth and yield, on Cd uptake by peanut and Cd accumulation in grey infertile soil (Haplic Acrisols)”.
The thesis purpose is to investigate the effects of Cd contained in oganic fertilizers (urban waste compost, pig manure and cow manure) or metal salt (CdCl2) on growth, yield and Cd uptake by peanut and Cd accumulation in soil (grey infertile soil at urban area of Ho Chi Minh City). The studies were conducted from June 2002 to July 2003 at the Environmental Protections Researchs Center, Analytical Chemistry and Biology Center and at The Experimental Station of the NLU, Ho Chi Minh City. The impact study of biosolids on Cd levels accumulating in soil and uptake by peanut was conducted using RCBD (two factors with three types of biosolid, eight levels with three replications). The impact research of metal salt (CdCl2) on Cd concentration accumulate in soil and plant uptake was conducted using RCBD (one metal, fine levels with three replications).
Some results of this field trial showed that:
- Germination rate, death rate and plant height of peanut in both biosolid and cadmium trials have no statistically significant difference. Yields in biosolid trials are significantly different but are not in metal trials. It means that, none of the treatments expresses any significant effects of Cd toxicity on either germination rate, death rate, plant height, biomass production or kenel yields. Yield reduction was thus not resulted from Cd phytotoxic effect. The dry-matter yields of the peanut grown on biosolid-amended soil were increased by the rate of biosolid application.
- The concentrations of Cd in cropping soil (T0, T1) and peanut (stem and kernel) tend to increase with increasing rate of biosolids and CdCl2 salt application.
- After havest, decreasing of Cd levels (%) in soil tends to reduce with raising amount of biosolid application, in which, Cd concentration is significantly higher in soil ammended with pig manure than the soil ammended with urban waste compost and cow manure.
- Cd uptake in plant tends to be increased obviously with inseasing amount of organic matter and metal salt rates. In grain the trend is not significant.
- The concentration of Cd accumulated in soil ammended with pig manure is higher than in soil ammended with cow manure and waste compost, but the Cd uptake trend in kernel is opposite in case the soil fertilized with cow manure.
- Correlations between soil pH and Cd levels were not significant (pH has no effect to Cd accumulation in soil, plant and kenel uptake in this biosolids trial).
- After harvest, the analysis of Cd levels in different soil layers show that Cd leached from 0 – 15 cm layer into deeper layers. Especially, in treatments Cd 4 (0,42 mg Cd/kg soil) and cow manure application. The differences were considered to be very significant between the treatments according to soil layers.
Nguyen Van Phong
“Studies on growth, development and apply methods of pruning, floral inducing and fruit-set improving to some Thai mango cultivars grown at Dong Tien farm, Ho Chi Minh City”
The thesis includes four experiments.
Experiment 1: Studies on growth and character of some Thai mango cultivars.
Five Thai mango cultivars, namely Nam Dok Mai, Khieo Sawoei, Man Duon Cao, Pal Kun Xi, Chok Anan and a Vietnamese mango Cat Hoa Loc used as a control. All mango cultivars have been planted at Dong Tien farm since 1994. The results showed that Thai mango cultivars have grown better and given higher yield than Cat Hoa Loc cultivar. They adapted to the climatic conditions of Ho Chi Minh City. Pal Kun Xi and Khieo Sawoei having the high yield, good quality are recommended due to they give high income to growers.
Experiment 2: Apply some pruning methods to mango
A factorial experiment was carried out at Dong Tien Farm; factor A: six mango cultivars (Nam Dok Mai, Khieo sawoei, Man Duon Cao, Pal Kun Xi, Chok- Anan and Cat Hoa Loc), factor B: four pruning methods (thinning out, left one terminal shoot, left two ones and left three ones). The results indicated that the thinning out pruning method gave the highest yield for all cultivars, because mango often emerge inflorescences on the top of terminal mature shoots. In 2001- 2002 fruiting season, the treatment “thinning out” gave 40.39 kg per tree, whereas the treatment “left one terminal shoot” gave only 23.96 kg per tree.
Experiment 3: Induce flowers to mango by potassium nitrate
Two factor completely randomized experiments, factor A: six mango cultivars (Nam Dok Mai, Khieo sawoei, Man Duon Cao, Pal Kun Xi, Chok Anan and Cat Hoa Loc), factor B, 2 levels: apply potassium nitrate at the rate of 3% and control (0%). These experiments were conducted in August, November and December. In November all cultivars gave the best results because of high rainfall in August and fog in December. All mango cultivars responded to potassium nitrate (3%). There are highly significant differences among treatments. The treatment potassium (3%) gave the yield two fold compared to control treatment.
Experiment 4: Apply leaf fertilizers to mango in order to improving yield.
Two factor completely randomized experiment was carried out, factor A: three mango cultivars (Nam Dok Mai, Khieo sawoei and Cat Hoa Loc), factor B, four leaf fertilizer treatments: HPC-B97, Mango 97, Progibb, Thien nong and a control treatment, 3 replications. The result showed that apply leaf fertilizers gave higher yield than control treatment. The yields were 47.5 kg per tree, 34.2, 36.2, 49.4 and 25.1 for the treatments of HPC-B97, Mango 97, Progibb, Thien nong and control treatment in the year of 2001, respectively.
In general, Thai mango cultivars in the experiments adapted to the climatic conditions of Ho Chi Minh City. They thrive well and give higher yields than Cat Hoa Loc. Particularly, the green mango cultivars such as Khieo Sawoei and Pal Kun Xi. The consumers pay the high prices for these fruits, that mean they accept the new mango fruits, therefore these cultivars are highly recommended. Simultaneously, the application of thinning out pruning and leaf fertilizers are also proposed.
Nguyen Van Thai
“The effect of low frequency tapping system incorporated stimulated application to yield and latex physiological parameters of clone PB 235”
was conducted by NGUYEN VAN THAI under supervised by Dr. PHAM HONG DUC PHUOC and Mr. DO KIM THANH. The experiments was set up at field 136, Tan loi rubber Plantation, Dong Phu Rubber Company, Binh Phuoc province. The trial was laid out in Randommized Complete Block Design including four treatments, and 3 replications with total 12 experimental units, the size of experimental units is one tapping task (1.2 hectare). The rubber tree was tapped on half-spiral system with two tapping frequencies, viz. third daily tapping (d/ 3) and fourth daily tapping (d/4). These tapping systems were combined with stimulation frequencies of 4, 6 applications per year, viz.:
• 1/2S d/3 unstimulated (control);
• 1/2S d/4 unstimulated
• 1/2S d/4 ET 2.5% Pa 0.7(1) 4/y (4 applications a year)
• 1/2S d/4 ET 2.5% Pa 0.7(1) 6/y (6 applications a year).
Rubber yield and other parameters were recorded from April, 1998 to January, 2001. The exploitation of rubber tree has been done on virgin bark since the first year of opening for tapping. In general, the growth and density of tapping trees of the trial are in good conditions (400 tapping trees per hectare). All the trees in the trial have been treated the same maintenance practices and quantity of fertilizer.
The results showed that low frequency tapping system of d/4 with 4 – 6 stimulations gained rubber yield 13 – 17% higher than that of the control frequency tapping of d/3. The application of latex stimulant of ethephon 2.5% with 4 – 6 rounds per year on clone PB 235 gave higher yield without the effect to growth and other parameters such as annual girth increment, incidence of dryness…
Low frequency tapping system of d/4 consumed lesser virgin bark 2.5 – 3 cm per year. Moreover, this tapping system reduced number of tapper in the plantations to save the cost of tapping from 8 – 10%; therefore, to increase the net interest per tapping task per year by 20 – 42% in comparision to d/3 tapping system.
Rubber clone PB 235 has high and early potential rubber yield. The reduction of tapping frequency produced a good result of physiological parameters of sucrose, inorganic phosphorus and thiols contents.
The obtained data of physiological parameters also supplemented the background knowledge in latex diagnosing methodology.
Pham Ba Tung
“Studies on the production status and applying some intensive cultivation measures for pineapple (Ananas comosus [L.] Merr. cv Smooth Cayenne) at Tho Vuc state farm, Xuan Loc dist., Dong Nai province”.
The studies were carried out under the supervising of Dr. Nguyen Van Ke, Head of Food, Vegetable and Fruit Crops Department of Nong Lam University.
The studies consist of two parts.
Part 1: The survey on pineapple production situation at Tho Vuc state farm
The results showed that pineapple, a new crop, has introduced to Tho Vuc since 2001. So far, the pineapple area attained about 57ha. On average, the area per household varies from 1 to 1.5ha. Density varies from 40,000 to 80,000 plants per ha. But there is only one plot has a high density, 80,000 plants per ha. The survey has also revealed some constraints, such as:
- Whole farmers had not experiences on pineapple cultivation.
- Suckers imported from China have not been classified leading to the growth and the development of pineapples unevenly.
- Fertilizers applied to pineapple were not balance among elements. Phosphorous was supplied higher than the requirement of pineapple, whereas nitrogen and potassium were applied small amount, from 1 to 8g per plants compared to the levels in the world about 8g N and 12g K2O per plant.
- The pineapple plots cultivated conventionally have weed density too high. Weed was controlled by herbicides and by hands.
- Mealy bug wilt virus and heart rot diseases occurred on the fields. They were controlled by insecticides and fungicides.
- The farmers were lack of the cultivation techniques, capital and good quality suckers.
- on an average, the yield was 26 metric tons per ha, whereas the experiment plot was 90 tons.
Part 2:Applying some intensive cultivation measures to pineapple
Trial 1: Study on the adjusting fertilizer to Smooth Cayenne pineapple. This experiment includes 2 treatments, namely: 1) Control 2) Applying fertilizer based on D-leaf analysis according to the method of J. D. Glennie.
The results showed that the treatment of adjusting fertilizer had the growth and yield increased significantly, compared to control treatment the yield increased 13,4 tons per ha. Based on the soil and D leaf analysis, the fertilizer formula was proposed: 7-7.5g N, 2.16g P and 8-9g K per plant per crop.
Trial 2: Applying drip irrigation to pineapple: aimed at comparing drip irrigation to spray irrigation by hand, this trial has 2 treatments: Control and drip irrigation.
The results showed that drip irrigation in dry season with 18.5 hours per month, about 3.4mm per day make the length and weight of D leaf better than those of control treatment. Besides, statistical analysis of yield showed that the productivity in the drip irrigation treatment increased 33,6 metric tons per ha compared to control treatment.
Trial 3: Applying plastic mulching to pineapple cultivation. This trial includes 2 treatments: Control and plastic mulching.
The results indicated that the mulched plots gave the number of leaves, weight and length of D leaves higher than those in control treatment (increasing 2.7 leaves per plant, 12.4g and 9.8cm per leaf). It also make the weight of weed decrease and the yield increase 26.3 metric tons per ha compared to control treatment.
Genarally, the drip irrigation, the plastic mulching and the fertilizer correction make the yield increase greatly. So in the year of 2003 the Department of Agricultural and Rural Development decided to choose Tho Vuc State Farm as a high technique pineapple zone and invested more than 30 ha this year.
Phan Dinh Thao
“Application of modeling method for rubber yield prediction on GT 1 and PB 235 clones” was carried out from 2002 to 2003, on the actual data obtained at Dong Phu and Dau Tieng Rubber Companies. The total rubber area chosen for recording data comprises of 346.25 hectares of GT 1 (15 fields) and 375.61 hectares of PB 235 (17 fields) at Dong Phu; and 524.10 hectares of GT 1 (23 fields) and 1942.99 hectares (84 fields) of PB 235 at Dau Tieng. The data were subjected to linear and nonlinear correlation analyses. The following relationships have been considered (i) age of tapping and individual yield (kg/tree/year); (ii) age of tapping and density of tapped trees (number of tapped trees per hectare); and (iii) age of tapping, density of tapped trees and field production (kg/ha/year). The best-fit model was based on the highest correlation coefficient and level of statistical significance. Regression analyses were carried out to establish the mathematical models according to the pre-determined type of model.
The result showed that there was an increasing individual yield with the age of the tree on GT 1 and PB 235 clones at Dong Phu and Dau Tieng. The relationship of age of tapping (x) and individual yield (kg/tree/year) (y) can be expressed using the lny = b0 + b1lnx mathematical model. All models have high correlation coefficients (R = 0.9626 - 0.9939) and regression coefficients of models were highly statistically significant (P < 0.05) on both clones and sites.
The relation between age of tapping (x) and density of tapped trees (number of tapped trees per hectare) (y) followed the lny = b0 + b1x + b2x2 + b3x3 mathematical model. Results of regression analysis showed that all models have high correlation coefficients (R = 0.9915 - 0.9984) and regression coefficients of models were highly statistically significant (P < 0.05) on GT 1 and PB 235 clones at Dong Phu and Dau Tieng. These models showed that the number of tapped trees increased with the age of tapping in the period of 1st - 4th years of tapping and get a maximum at 5th and 6th years of tapping, after that it slightly decreased during 7th - 10th years of tapping.
In the fields where maintenance and tapping were following standard procedures from General Rubber Corporation (GRC), yield per hectare (y) in relation to age of tapping (x1) and density of tapped trees (x2) can be expressed by the lny = b0 + b1lnx1 + b2lnx2 mathematical model. Results showed that all models had very high correlation coefficients (0,9866 - 0,9977) and regression coefficients of models were statistically significant (P < 0.05) on GT 1 and PB 235 clones at Dong Phu and Dau Tieng. The combination of two independent variables, age of tapping (x1) and density of tapped trees (x2) could strongly support the yield prediction on GT 1 and PB 235 clones in the period of 1st - 10th years of tapping at Dong Phu and Dau Tieng. In other companies where the plantations were maintained and tapped following standard procedures from GRC, the yield could also be predicted by these mathematical models. In connection with these models, it is required the knowledge on agronomy, situation of plantion, position of tapping cut for slightly adjusting the yield prediction.
A computer-program has been established for yield estimation based on mathematical models to allow fast and easy prediction of rubber yield.
Trương Vĩnh Hải
“Effect of bio-organic fertilizer on yield and quality of some vegetables on the grey soil area of HCM City”,
has been conducted at Dong Tien experimental station of HCMC Seeds Company (Hoc Mon District, HCMC) from February. 2001 to March 2002).
The study was carried out under the supervisor of Dr. Pham Hong Duc Phuoc, Head, Department of Plant Physiology, University of Agriculture and Forestry, and Dr. Nguyen Dang Nghia, Head, Department of Soil and Fertilizers research, Institute of Agricultural Science of South Vietnam. The study consists of two parts :
- Part 1 : Assessment the effect of some bio-organic fertilizers, on yield and quality of Pak Choi and cucumber under field condition.
- Part 2 : Assessment the effect of some bio-organic fertilizers on yield and quality of leafy vegetables at grille house condition.
Part 1 consists of 2 tests, carried out on the same soil in two crops (Pak Choi – Cucumber). In the experiment , Pak Choi was followed by a Cucumber. On each vegetable, the test has been arranged under split-plot design, with five sources of fertilizes as main factors and two application rates of animal manures as sub plot , replicated for 3 times. The plot size was 20 sqm.
The part 2 of research is carried out in the grille house, consisting of 6 tests, arranged at a fixed place with a consecutive period of 6 crops. The experiments has been arranged under randomized complete block design, with 4 treatments, 3 times replicated. The plot size was 10sqm.
The result shows that the yield of Pak Choi grown in the field with bio-organic fertilizer formula, reaching from 21.1 tons/ha to 22.7 tons/ha; in the meantime, with chemical fertilizer formula, it reaches only 18.4 tons/ha. This difference has a statistically significant . The nitrate content (NO3) in the leaves dealing with bio-organic fertilizer treatments, is much lower compared to the authorized threshold (1,000mg/kg). In respect of cucumber, the yield of bio-organic fertilizer formula has reached from 33.3 tons/ha to 36.3 tons/ha, a statistically significant difference compared to chemical fertilizer treatment. The Nitrate (NO3) content in the cucumber in treatments, is very low, compared to the authorized threshold (150mg/kg). Besides, the bio-organic fertilizer allows the pH numerical value of the soil after many crops.
Regarding the vegetables in grille house, the bio-organic fertilizer will give a higher yield compared to the control experiment, and the nitrate content (NO3) is much lower than standar level . The use of bio-organic fertilizer for vegetables culture in grille house, might replace completely the manure, but ensure their yield and quality.
Besides, the economic effect of the bio-organic fertilizer’s use in vegetables’culture, is higher compared to the control experiment.
Nguyễn Thị Ngọc Loan
“ Applying land evaluation method of FAO for conversion of some major plants at Lam Ha district, Lam Dong province”
was carried out at Laâm Haø from August 2002 to August 2003. The results of this study were as following:
- Natural environment: Laâm Haø district with monsoon tropical climate was relatively appropriate to develop of many long – term industrial crops such as coffee, tea and mulberry plants. However, shortage of water in dry season in this area had significantly affected to agricultural production. Investigating results showed that the rate of population increasing, specially migrate population increasing was very high. Ninety percent of total labours was to service in the domain of agriculture.
- Social economical conditions: In recent years, the economical development has rapidly increased whereas infra-structural development has relatively been slow. The foreigner investment has been limited.
- Soil characteristics: Based on the soil map of Laâm Haø performed by Sub – National Institute of Agriculture Planning and Projection, there have been 6 soil groups and 12 soil mapping units as following: 118.190 ha of ferralsols (74,44%), 16.138 ha of gleysols (10,16%), 12.674 ha of humic ferralsols (7,98%), 4.232 ha of fluvisols (2,67%), 3.342 ha of acrisols (2,11%), 2.764 ha of luvisols (1,74%).
- Land characteristics: By overlaying the factor maps such as soil group, slope and so on, a land unit map was established at scale of 1/50.000. There were 48 land mapping units in this area.
- Present land use and land use systems for agriculture: The surveying results showed that there were 6 major kinds of land use, 20 of land use types with 79 land use systems and 64 land use systems were proprosed for agriculture production. The agricultural area was 48.491,89 ha that was approximatively 30,34 percent of total area. The area of food, vegetable, short – term industrial, long – term industrial, fruit and other perennial crops were respectively 6.988 ha (14,4%), 1.544 ha (3,18%), 1.193 ha (2,46%), 37.729 ha (77,8%), 465 ha (0,96%) and 73 ha (0,15%).
- Land suitability: There were 53.474 ha suitable for agricultural production.
- Propose: From above results some propositions were as following:
Conversion of 4.564 ha of coffee cultivated on unsuitable land in to cutting tea (1.545 ha), hybrid mulberry (165 ha), fruit plant (1.035 ha) and forest trees (1.719 ha) .
Otherwise, in oder to improve both quantity and quality of products, it should be converse 5.000 ha of robusta coffee to arabica coffee. 175 ha of tea growed by seed should be converted to tea growed by cutting, 960 ha of mulberry to hybrid mulberry.
However, to promote the process of conversion rapidly and effectively, it is necessary to support other solutions such as applying modern technologies, policies of land development, credit and tax. Besides, development of post – harvested processing technologies and product promotion programs were also concerned.
Võ Quốc Khánh
“The effect of peat used as fertilizer in peanut production”
These experiments have been conducted on grey soil (Acrisols), with VD1 local LY varieties. The 2 pot experiments have been laid out under RBCD design in HCMC; and the field experiment - under split-plot design, in Go Dau District, Tay Ninh Province.
Results :
The peat has good effect on growth, development and yield of peanut.
People can use peat to replace manure. On a basic applicationof N-P-K = 30-60-90, we apply additionally 1.47 tons of peat/ha and can reach a yield which is equivalent to the output of 5 tons of manure/ha application.
In case of combined application of 5 tons of peat/ha, we can reduce 28.96% NPK fertilizer quantity with a stable guarantee of peanut yield.
The treatment of 100% base application N-P-K = 30-60-90 combined with 5 tons of peat/ha gave the highest yield of 3555.7kg/ha over the control with the same NPK close up to 23.06%. The treatment of 100% NPK basic application, combined with 1.47 tons of peat/ha gave an yield of 3316.5kg/ha exceeding the control 15.58%, with the highest net interest, also the highest profit rate of 3.03. The VD1 and local LY peanut varieties have no difference when being applied fertilizers.
Besides, the fermented peat has a good effect on soil properties: it improved soil pH, increased soil absorption capacity and soil organic matter content
Vương Phấn
Survey on evaluation of limiting factors to cashew yield in main cashew growing regions
of daklak province
The cashew nut yield in the main cashew growing areas of Daklak province is quite low ranging from 400 to 600 kg raw nut/ha. Besides the major limiting factor i.e. unselected planting material, in each region there is a number of other factors that negatively affect cashew yield. Rains often occur in flowering and fruiting period in Dak R’laêp district affecting the fertilisation, therefore the fluctuation of yield depends on climatic condition of each year despite of fertile soil. In EaKar district, due to the rains ends late, flowering, fruiting and harvesting season of cashew trees is also later than other regions from 1 to 1,5 months. The time of the supply of raw nuts is more favourable for factory's process, but the production maybe decrease in years when heavy rains come earlier. Poor soil fertility and lack of fertilizer in EaSoup region make the nut yield lower and lower. Although Cu M'gar has good soil and the most favourable climatic conditions compared to these of other regions the cashew nut yield is not high because of lack of good investment and management.
Intergrated practical measures should be implemented to improve cashew yield in these regions: such as application of high yield clonal varieties, fertilizer, pruning, and plant protection (especially Helopeltis causing flower and fruit drop).
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Last modify: 12-09-2008
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