عنوان مقاله [English]
Sunflower (Helianthus annuus L.) is one of the plants cultivated for oil or seed. Sunflower oil contains many useful fatty acids. One of methods to increase plant yield and decrease input consumption is transplanting. Transplanting can increase seed yield components such as head number per plant, seed number per head, 1000-seed weight. Transplanting increased seed yield and quality compared to direct seeding due to no frost at the beginning of growth season and increasing flowering length. By delaying transplanting, seed germination or transplant establishment is reduced. Time interval from seeding till beginning and terminating flowering length can be reduced by delaying at seeding, but by transplanting flowering duration length increases. Drought losses crop productions especially at plant critical growth periods such as seed filling stage. In arid and semi-arid areas like Iran, water shortage leads farmers to plant low- water crops. By transplanting of sunflower, water can be saved, because seedling can be grown by a little water in controlled condition. In addition, some plant growth stages coincide with cool and rainy weather in spring. Many farmers use transplanting for warm season crops, but transplanting of sunflower has not been well studied. This research was aimed to assess sunflower transplanting under common sowing date and early sowing in Kermanshah climate condition.
Material and Methods
An experiment was conducted at greenhouse and research field, campus of agriculture and natural resources, Razi University in 2015 and 2016. In the first year, factors included three planting methods (direct seeding, 4-week transplanting and 6-week transplanting) and sowing date (early sowing, common date sowing). In the second year, treatments included 4- week transplanting at early sowing (superior treatment in the first year) and direct seeding (control). At harvesting stage, four plants per plot were selected and traits such as plant height, stem height, stem diameter, leaf number, internode length, leaf width, leaf length, leaf fresh weight, stem fresh weight, seedling fresh weight, leaf dry weight, stem dry weight and biomass were measured. Leaf greenness was measured by SPAD device and stomatal conductance was measured by porometer device. Leaf area was determined by digimizer software. Leaf relative water content, chlorophyll a and b, seed yield and yield components also were measured. Data were analyzed by SAS software. Mean were compared using LSD test.
Results and Discussion
Analysis of variance of 2015 data, showed that planting method and planting date had significant effect on plant height, leaf relative water content, dry matter and leaf area. 4-week transplant at early planting date had the highest dry matter production and leaf area selected for the second year. It seems that by delaying in transplanting, sunflower plant become more sensitive to cold air and low temperature damages plants, so lower dry matter production was produced. Results of the second year showed that transplanting increased green leaf number, leaf area, chlorophyll a, plant fresh weight, plant dry weight, leaf to stem ratio, stem length, plant height, seed number per head, dehulled seed weight, hull weight, seed yield and 100-seed weight. It seems in transplanting, maximum stem length, plant height, green leaf number and leaf area was occurred when sunlight was maximum, so plant had higher radiation use efficiency and dry matter production. In addition, transplanting had higher seed yield than seeding probably due to weed suppression, rapid establishment, shorter growth duration and faster flowering. Transplanting increased seed yield and weight due to lack of coincidence of plant critical stages to adverse environmental conditions, suitable plant cover, prolonging the grain filling period and store assimilates in grain.
In conclusion, it is suggested to plant 4-week sunflower transplant at early date in Kermanshah climate condition.