Study on the radiation use efficiency and quantitative and qualitative yield in lavender and chamomile additive intercropping under the influence of cow manure and chemical fertilizer

This study was conducted to investigate the potential of lavender (Lavandula angustifolia Mill.) and chamomile (Matricaria chamomilla L.) additive intercropping to improve the radiation use efficiency as a factorial based on the randomized complete block design with three replications at the research farm of Bardsir Agricultural Faculty, Shahid Bahonar University of Kerman, in 2018-2019 crop year. The experimental treatments included the fertilizer at four levels (1- Control, 2- NPK: 69-46-25 kg ha-1, 3- Cow manure: 20 t ha-1, and 4- Combination the half values of NPK and cow manure) and the planting pattern at three levels (1- Sole cropping of lavender, 2- Sole cropping of chamomile, and 3- Additive intercropping of lavender (main plant) and chamomile (associated plant)). The results showed that the total leaf area index of the two plants in intercropping was significantly higher than the sole cropping of them. The combined application of cow manure + NPK caused the highest lavender dry matter (DM) (868 kg ha-1), chamomile flower yield (366 kg ha-1), essential oil percentage of chamomile (0.56%) and lavender (0.80%), and radiation interception (1321 MJ m-2) in all the planting patterns. There was no significant difference between the planting patterns in terms of essential oil percentage. Due to the canopy overlap of the two plants in the intercropping, the value of photosynthetic active radiation (PAR) intercepted during the growing season in the intercropping treatment was higher than the sole cropping of both plants. The land equivalent ratio (LER) in terms of PAR (LERPAR) varied between 1.33 and 1.37 in fertilizer treatments. The highest radiation use efficiency (1.63 g DM MJ-1 radiation) was obtained for chamomile in the intercropping at the cow manure + NPK treatment. In general, the results illustrated that the application of cow manure + NPK treatment and intercropping of lavender and chamomile could be an appropriate approach for more efficient radiation use and improving the quantitative and qualitative yield of the two plants.