Effects of Legume Cover Crops on Orange (Citrus sinensis) Fruit Weight and Brix

Recent reports show that orange yield and fruit quality is on the decline in Kenya’s coastal lowlands hence need for an efficient and sustainable production system. A field study was conducted in Vitengeni, Ganda and Matuga locations within the coastal lowland of Kenya from May 2012 to April 2015 to evaluate the effect of three legume cover crops on orange fruit weight and brix. The treatments included mucuna (Mucuna pruriens), dolichos (Lablab purpureus), cowpea (Vigna unguiculata) cover crops and fallow of natural vegetation as the control. The experiment was laid out in a randomised complete block design (RCBD) and each treatment replicated four times within the four blocks. Data collected were orange fruit weight, orange fruit brix, weather, soil texture and composition. The data was subjected to the analysis of variance (ANOVA) using the procedures of R statistical analysis software version 3.3.2 (R Core team, 2015). Mean separation was done using the least significant difference (LSD) at 5% level of significance. The results from the study showed that mucuna, dolichos and cowpea significantly (P=.05) increased fruit weight and brix. There was interaction effect between treatments and sites. Mucuna increased orange fruit weight by 12.4%, 10.5% and 7.6% for Ganda, Matuga and Vitengeni respectively. Orange fruit weight increased by 8.8%, 7.8% and 7.2% for Ganda, Matuga and Vitengeni respectively due to dolichos and 6.0% for Ganda due to cowpea. Orange fruit brix increased by 5.8%, 5.1% and 4.2% for Vitengeni, Matuga and Ganda respectively due to mucuna. Cowpea increased orange fruit brix by 4.6%, 3.8% and 3.2% for Vitengeni, Matuga and Ganda respectively. Orange fruit brix increased by 3.3% and 3.1% for Vitengeni and Matuga respectively due to dolichos. From the outcome of this study, mucuna is recommended for use in orange tree orchards as it is useful in improving yield and fruit quality.