Response of potato ( Solanum tuberosum L.) to manipulation of row spacing, fertilizer use, and intercropping with beans

Abstract

South western Uganda is the leading potato producer contributing 60% of Uganda’s national potato production.The rapid population growth from 39 million in 2018 to 44million to date (2022)has greatly contributed to land fragmentation continually leading to diminishing land parcels per house hold. Production has thus reduced to 4.3t/ha lower than the 25t/ha obtained under good management hencepathways to intensify potato production to meet population demands were highly required.The study intended to contribute to improved potato production through the generation of knowledge that will guide the development of a system of potato intensification by integrating crop management practices to suit farm resources and improve land use.The multi-locational split-split plot Randomized complete block experiments were established in Kabale,Rukiga,and Mbarara districts for two seasons. The study investigated the effect of fertilizer use (NPK and No NPK), plant spacing (75 cm ×30 cmand 60 cm ×50 cm), and intercropping plant arrangements of potato and beans (in ratios of 1:1, 1:2, 2:2, sole potato and sole bean) on the performance of potato.It also investigated the most effective plant arrangement in potato bean intercrops that would give better economic yields.Potato leaf area (cm2), number of marketable and un-marketable tubers per plot, total tuber yield per plot (t/ha), and bean yield per plot (t/ha) were collected from experimental units and were used as indicators of crop performance under different treatments. Land use efficiency in crop mixtures was also determined. Potato leaf area was significantly (p<0.001) influenced by location, spacing,and plant arrangement interactions. Wider potatoleaves for sufficient interception of irradiations in Kabale and Rukiga intercrops grew under one row of potato to one row of beans (1P:1B)and two rows of potato to two rows of beans (2P:2B) arrangements established at 60 cm ×50 cm respectively. Plant arrangement (p<0.001) and the interaction between, spacing and fertilizer (p<0.05) had a significant influence on potato yield. Maximum yields of potato, beans,and overall yield were achieved from fertilizer-treated intercrops of one row of potato to tworows of beans (1P:2B) established at 75 cm ×30 cm spacing.Plant arrangement by spacing(p<0.01) and plant arrangement spacing and fertilizer significantly (p<0.05) influenced marketable tuber yield. More marketable tubers in Kabale, Rukiga,and Mbarara were harvested from 1P:1B intercrops established at 60 cm ×50 cmbut fertilizer treatment enhanced marketable yield further particularly in Mbarara. Moreover, the highest biological efficiency in resource utilizationin terms of economic yield from crop mixtures was achieved from 1P:2B intercrops.Therefore intercropping potato ad bean was highly recommended for potato intensification, precisely by adding NPK to 1P:1B arrangements of 60 cm ×50 cm spacing for commercial potato production.Whereas, adding NPK to 1P:2B intercrops maintained at 75 cm ×30 cm spacing was highly recommended for ware potato production.