Effect of weather factors and nitrogen application on nectar secretion and honey production potential in sunflower

摘要

Sunflower is a highly important bee floral crop. The nectar secretion governs this parameter and is greatly influenced by cultivar, environmental factors and fertilizer application. Studies were conducted at Punjab Agricultural University, Ludhiana on sunflower hybrids (PSH 996 and PSH 1962) sown on different dates (January 31, February 10, February 20 and March 2) with three levels of nitrogen (45, 60 and 75 kg ha(-1)). Delay in sowing from January 31 to March 2 caused significant reduction in nectar secretion (12.66%) and increase in its concentration (5.38%). The daily mean temperature had significant positive (R-2 = 0.52 and 0.54) while mean relative humidity had negative (R-2 = 0.55 and 0.37) correlation with nectar total soluble solids (TSS).Nectar secretion and its TSS increased significantly only at nitrogen dose of 60 kg ha(-1) as compared to 45 kg ha(-1). Weather parameters have more pronounced effects on TSS at 45 kg ha(-1). Delay in sowing by one month resulted in reduction in honey production potential by 1.5- 1.8 kg ha(-1) . In addition to this, the reduced nectar availability due to delay in sowing may negatively effect in attracting and sustaining pollinators' populations and crop yield.