Radiation Use Efficiency and Yield of Pepper ( Capsicum annuum L. cv. California Wonder) under Different Irrigatio n Treatments

Abstract

This study assessed the optimum water need of peppe r ( Capsicum annuum L. cv. California Wonder) and the critical irrigation leve l to be applied in order to achieve a reasonable economic yield in water shortage conditi ons. In a controlled field experiment involving five different treatments, seasonal evapo transpiration for pepper fluctuated from 89 mm in the severe stress treatment (I 0.00 ) to 1,018 mm in the excess water application (I 1.25 ). The highest yield was obtained in the full treat ment where water in the root zone was refilled up to field capacity. In cas es of water shortage, applying water of 690 mm ensures an economical yield. Maximum leaf ar ea index was recorded in the full treatment (I 1.00 ), which enabled the pepper to receive more benefit from total incoming solar radiation (average, 2,387 MJ m -2 ). An average of 555.45 MJ m -2 was held by the pepper canopy throughout the whole growing season. Radiation use efficiency values on a dry yield basis were 0.69 g MJ -1 in 2011 and reached 1.07 g MJ -1 in 2012, since the leaf area index increased from 1.46 to 2.44. Therefore, averaged over two years, the peppers in the full treatment converted irrigation water of 88 8 mm and intercepted photosynthetically active radiation into the highes t yield of 75.5 t ha -1 , which was more efficient than the excess and deficit water applica tion treatments. Keywords: Intercepted photosynthetically active radiation, Pe pper, Photosynthetically active radiation, Radiation use efficiency, Solar radiatio n.