Growth and yield of sweet potato (Ipomoea batatas (L) Lam) as affected by variety and plant population in Umudike, south eastern Nigeria
A field experiment was conducted at the Teaching and Research Farm of Michael Okpara University of Agriculture, Umudike, during 2018 and 2019 cropping seasons to evaluate the growth and yield of sweet potato (Ipomoea batatas (L) Lam) as affected by variety and plant population in Umudike, South Eastern Nigeria. It was a 2 x 4 factorial research laid out in a randomized complete block design (RCBD) with three applications. Factor A comprised two sweet potato varieties (TIS-87/0087 and UMUSPO -1), while Factor B comprised varying plant populations (100,000, 50,000, 33,333 and 25,000 plants ha-1). Number of leaves per plant for both varieties and populations increased at 4 and 8 weeks after planting (WAP) and declined at 12WAP due to senescence. Although UMUSOPO -1 variety recorded more leaves over TIS-87/0087, higher number of leaves per plant for T1S-87/0087 150.8 (2018) and 154.8 (2019) and UMUSPO-1 (154.4 (2018) and 161.4 (2019) were recorded at 8WAP. Number of vines per plant, length of vines per plant and vine girths of sweet potato per plant increased at 4, 8 and 12WAP, suggesting that sweet potato varieties are likely to produce more vines, longer vines, and bigger vines as they increase in age. Planting population of 50,000 plant ha-1 produced highest number of leaves per plant of 47.0 (4WAP); 151.4 (8WAP); 100.4 (12WAP) and 59.2 (4WAP), 161.3 (8WAP) and 123.3 (12WAP) for both years, while 100,000 plants per ha-1 produced more vines, longer vines and bigger vines at 4,8 and 12WAP during 2018 and 2019 cropping seasons. Higher number of roots per plants (28.7 and 26.9); length of roots per plant (18.97 cm and 16.32 cm); weight of roots per plant (3.25 and 3.09 g) and root yield of 340 and 379 tha-1 were produced by UMUSPO -1 variety over T1S-87/0087 in both years. Variety TIS-87/0087 produced roots with girth sizes of 1.88 mm (2018) and 1.76 mm (2019) over UMUSPO-1 variety, although their performances were statistically similar. Planting population of 50,000 plants ha-1 produced higher number of roots per plant, length of roots per plant, bigger root girth per plant, heavier roots per plant and root yield during 2018 and 2019 cropping seasons, compared with other plant population with smaller values. UMUSPO-1 variety planted at a population of 50,000 stands ha-1 is recommended for the production of sweet potato in Umudike, South Eastern Nigeria.