Two prolonged cold spells in February and cool weather in March in the north have extended the growing period of rice before the blooming stage by seven to 10 days.
Despite this, farms have had high yields as farmers have used special cultivation techniques, a representative of the Ministry of Agriculture and Rural Development (MARD) said at a meeting in central Thanh Hoa province earlier this week to review the northern region's rice output.
The north has had an average yield of 6.2 tonnes a hectare, up 50 kilos against last year's winter-spring crop, the ministry said.
Northern provinces have planted more short-term rice and high-quality rice varieties this year, and the cultivation of hybrid-rice varieties has increased productivity and output.
Deputy Minister Le Quoc Doanh said farmers should closely monitor their fields to prevent disease outbreaks.
The northern region has planted over 1.1 million ha of rice, down 1,500 ha against the 2012-13 winter-spring crop.
In the central region, rice yields in many provinces like Quang Nam and Quang Ngai have reached a record high.
Quang Ngai has planted over 38,800ha of rice in the winter-spring crop, harvested an average yield of 5.7 tonnes per hectare, said the province's agriculture department.
The department attributed the high productivity rate to several factors, including high-quality and disease-resistant seeds, appropriate cultivation methods and sufficient irrigation water.
The province has faced several unfavourable weather conditions, such as prolonged rain, floods and cold spells after initial planting, and drought in the middle of the crop.
In Quang Nam province, the winter-spring crop has achieved a record-high yield, said the province's Department of Agriculture and Rural Development.
The province's rice output is expected to reach 244,000 tonnes, up 6,500 tonnes against last year.
The ministry said farmers in the Mekong Delta, the country's rice basket, had completed the harvesting of 1.6 million ha of the winter-spring crop, with an average yield of 6.8 tonne per ha, an increase of 0.3 tonnes over the estimate by the ministry's Plant Cultivation Department.
The delta this year also expanded the area of large-scale rice fields to over 100,000ha for the winter-spring crop, up 34,000 ha against last year, according to the Steering Committee for Southwest Region.
An Giang province and Can Tho city have the largest areas of large-scale rice fields in the delta. Farmers of these fields sign contracts with companies to grow high-quality rice for export.