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EFFECT OF LEGUMINOUS COVER CROP (Calopogonium mucunoides DESV.) ON LEAF N, CHLOROPHYLL CONTENT AND GAS EXCHANGE RATE OF BLACK PEPPER (Piper nigrum L.)

Planting black pepper in a leguminous cover crop establishment can contribute to a healthier environment apart from being able to reduce the cost of N fertilizer application. The use of leguminous cover crops including Calopogonium mucunoides have known to bring benefits such as fixing nitrogen and managing soil moisture. This study was designed to investigate the effect of C. mucunoides application on leaf total nitrogen (N) as well as to examine the role of N in affecting the chlorophyll content and gas exchange rate of black pepper. The field experiment conducted was a randomized complete block design (RCBD) with two treatments replicated nine times. Treatments were control (C0) which was Piper nigrum vines without application of C. mucunoides cover crop and Calopo cover crop (C1), Piper nigrum vines with application of C. mucunoides cover crop. Soil volumetric water content (VWC) was significantly (p < 0.05) higher in a C. mucunoides establishment than that of the control. Soil total organic carbon (TOC), soil total nitrogen (N) and soil available phosphorus (P) were significantly (p < 0.05) higher in a C. mucunoides establishment. Leaf total N, photosynthetic rates (A), stomatal conductance (gs), and transpiration (E) of the C. mucunoides treatment were significantly (p < 0.05) higher than that of the control. Furthermore, strong relationships have been developed between leaf total N – leaf chlorophyll content as well as A – leaf chlorophyll content. Consequently, higher rates of photosynthesis under conditions of high nitrogen are often attributed to increase in chlorophyll content. Therefore, incorporating C. mucunoides in black pepper vineyards can increase the photosynthetic rate of Piper nigrum by improving few soil properties.