Foliar Boron Application and Row Spacing Effects on Growth, Yield and Protein Contents of Lentil (<i>Lens culinaris</i> Medic.)

Sufficient supply of foliar boron is essential for the appropriate productivity of lentil, particularly in poorly fertile soil. Therefore, field experiments were carried out at two locations (Maru and Mushaqar) in Jordan during the winter growing season 2021/2022 to evaluating the impact of foliar boron levels (0, 0.2, 0.3, and 0.6%) on the physiology, growth, yield, and grain protein contents of the local lentil variety (Jordan 2) under different row spacing (17.5 and 35 cm). The results revealed that the Maru location outperformed another location for increasing transpiration rate, plant height, days to flowering, yield, and yield attributes while reducing protein contents. Row spacing of 35 cm had significantly higher physiological performance, yield, and yield attributes than row spacing of 17.5 cm, except for instantaneous water use efficiency, straw yield, and thousand seed weight. Foliar 0.2% boron was the best treatment since it increased total chlorophyll content, stomatal conductance, transpiration, photosynthetic rate, and protein content by 9.5, 39.9, 22.2, 25.9, and 11.2%, respectively. Furthermore, foliar 0.2% boron improved grain yield higher at row spacing of 35 cm than those at row spacing of 17.5 cm. However, foliar 0.6% boron decreased grain yield by 8.5% and 3.6% at row spacing 35 cm and 17.5 cm, respectively, indicating this high concentration of boron acts as toxicity. Overall, it is highly recommended to use foliar rates of boron ranging between 0.2% and 0.3% to enhance the seed yield and protein content of lentils at different row spacing. These results suggest that optimum row spacing and foliar boron are useful approaches for lentil’s sustainability in semiarid areas.