Oilseed crops require several micronutrients to support their physiological functions
and reproductive phases. A deficiency of these nutrients can significantly reduce the yield and oil
quality of oilseed crops. Soil application of micronutrients can reduce their deficiency and improve
plant growth, yield, and oil quality. Oilseed rape (Brassica napus L.) is an important oilseed crop
that produces oil with low levels of saturated fat and high levels of beneficial omega-3 fatty acids,
which renders it a widely used cooking oil. However, the yield and oil quality of oilseed rape
are significantly affected by the deficiency of boron (B) and zinc (Zn). This two-year field study
determined the influence of sole and combined soil application of B and Zn on the physiological
attributes of plants, seed and oil yields, and oil quality under semiarid climatic conditions. Nine
different B and Z combinations, i.e., B0 + Zn0 (control), B0 + Zn8, B0 + Zn10, B1 + Zn0, B1 + Zn8,
B1 + Zn10, B2 + Zn0, B2 + Zn8, and B2 + Zn10 (kg ha−1), were included in the study. Sole and
combined application of B and Zn significantly altered physiological attributes, seed and oil yields,
and oil quality. The highest values for plant height, number of siliques per plant, number of seeds per
silique, 1000-seed weight, seed and oil yields, oil quality (higher stearic acid, palmitic acid, oleic acid,
linoleic acid, linolenic acid, and lower erucic acid), and physiological traits (protein concentration,
soluble sugar concentration, chlorophyll concentration, photosynthesis and transpiration rates, and
stomatal conductance) were recorded with the combined application of 2 + 8 kg ha−1 B and Zn,
respectively, during both years of this study. The lowest values of yield- and oil-quality-related traits
and physiological attributes were recorded for the control treatment. A dose-dependent improvement
was recorded in B and Zn contents in leaves, and the highest values were recorded with the combined
soil application of 2 + 10 kg ha−1 B + Zn, respectively. It can be concluded that 2 + 8 kg ha−1 B + Zn
should be applied to oilseed rape for higher seed and oil yields and better oil quality under semiarid
climatic conditions.