Thesis title: Study on cultural techniques to increase effects of spring soybean production on one – season terraces in high regions of Yen Bai province.
Speciality: Crop science. Code: 62.62.01.01
Name of postgraduate: Pham Van Dan
Name of supervisors: Ass. Prof. Dr. Nguyen Van Tuat
Dr. Le Quoc Thanh
Training Unit: Viet Nam Academy of Agricultural Sciences (VAAS)
Briefly new achievements of the thesis:
- The thesis is a scientific work that studied synchronously in varieties and integrated intensive farming in order to increase the sping-soybean production efficiency in one-season terrace in Yen Bai province. It is practical and adapts to production demand in highlands in Yen Bai province and the northern mountainous province of Vietnam. Exploiting land potential that is fallow annually will improve coefficient usage and soil fertility. Besides, it contributes to increase soybean productivity and decrease the number of soybean importation.
- Conditions of weather and land in spring on terraces in the high regions of Yen Bai province were suitable to the characteristics of the soybean plant. The area of one – season terraces in Yen Bai was quite large, it was about 3000 - 3.500 ha. However, there was only 5.3% of the terrace area planted soybean in spring which had low yield (about 12.5 quintals/ ha). The main reasons that limited spring soybean production on terraces included lack of appropriate soybean cultivars and production technique guidelines; drought and coldness in early spring, rain at harvest time and damage of wandering livestocks.
- There were two soybean cultivars identified to adapt the conditions in spring on terraces in high regions of Yen Bai. The first cultivar was ĐVN6 which had 88 – 96 days of growth duration; achieved stable and high yield with 16.8 – 23.4 quintals/ha. The second one was ĐT26 which grew for 93 – 102 days; reached stable and high yield with 18.5 – 24.5 quintals/ha.
- The suitable time to cultivate both these cultivars in spring was from 1st March to 15th March annually. The appropriate crop density to plant these cultivars in spring on one – season terraces in Yen Bai province was 30 – 40 plants/m2. The amount fertilizers which brought the highest yield and economic effects for planting 1 ha of these cultivars contained 40 kg N, 90 kg P205, 60 kg K2O; 500 kg of Song Gianh micro-organic fertilizer (SGOM) and 300 kg of powdered lime for basal fertilizing.
- The model of applying cultural techniques for producing spring soybean on terraces had considerable higher yield than the control. For instance, model of planting the ĐVN6 cultivar achieved the yield of 18.8 quintals/ha which was 4.7 quintals/ha (33.3%) higher than the cultivar control ĐT12, and model of planting the ĐT26 cultivar had the yield of 20.6 quintals/ha which was 5.6 quintals/ha (37.3%) higher than the cultivar control DT84.