Mabeka, s., Svotwa, e. and katsaruware, R. d. THE EFFECTS OF RELAY CROPPING SWEET POTATO (IPOMEA BATATAS) AND COW PEAS (VIGNA UNGUICULATA) ON THE PRODUCTIVITY OF THE COMPONENT CROPS. Mabeka, s., Svotwa, e. and katsaruware, R. d. RIOSET, 2016. NUST, BULAWAYO, ZIMBABWE. 31 AUGUST-3 SEPTEMBER 2016

Introduction and background The sweet potato - dicotyledonous plant -Convolvulaceae. starchy, sweet-tasting, tuberous roots are a root vegetable. uses include income generation, climate smart livestock fodder Cowpea -legume family adaptable to semiarid tropics, fix N. A drought-tolerant and warm-weather crop – Climate change

Aim To investigate the effects of cowpeas and sweet potato relay cropping on the growth rate of sweet potatoes and yields of component crops (sweet potatoes and cowpeas).

Hypothesis We hypothesize that the cowpea and sweet potato relay cropping affects the growth, development and yield of sweet potato and cowpea. We also hypothesized that cowpea and sweet potato relay cropping improves the land use efficiency of the production system.

Materials and methods Site Gokwe South communal area, Midlands Province in Zimbabwe Natural region IV of Zimbabwe -average annual rainfall of 650 mm, Summer temperature average is 37oC while the winter temperature average is15oC. The experiments were set up in blocks 1.5 m apart. Each block consisted of raised beds 1 m apart.

Experimental design an experiment in a randomized complete block design (RCBD) with 6 treatments CBC2 cowpea variety , Cordner sweet potato variety

Table of treatments Treatment 1 Pure standard fertilized sweet potato Sweet potato + 1 row cow peas Treatment 3 Sweet potato + 2 row cow peas Treatment 4 Unfertilized pure sweet potato Treatment 5 Pure 1 row cow peas Treatment 6 Pure 2 rows cow peas

Field activities Beds with 2 rows cow peas had inter row spacing of 50 cm and in row 30 cm. The beds with 2 rows cow peas had 20 planting stations. Beds with one row cow peas, had in row spacing of 30 cm. Each bed of cow peas with one row had 10 planting stations and a total of 240 cowpea seeds were used. All sweet potato rows were planted at the middle of the beds with in row spacing of 30 cm. Each bed had 10 planting stations. 160 terminal sweet potato vines were used. The vines were 30 cm long and were planted to a depth of 5 cm leaving 10 cm lengths uncovered. The cow peas were covered to a depth of 5 cm.

Field practices continued Compound D (N8P14K7) was applied at a rate of 200 kg ha-1. Planting dates for the component crops were staggered by 30 days. Cowpeas were planted under irrigation. When the cow pea crops had reached flowering stage, vines of 30 cm long each were planted at the middle of the bed leaving 10 cm vine length above the ground

Data collection and analysis Vine length measurements were done every week Mass of sweet potato and cow peas were weighed at harvesting using a digital scale. Data was analyzed using Gen Stat and graphs were constructed.

Vine length at 3WAP

Results and discussion

Vine length at 7WAP

Vine length at 9WAP

Vine length at harvesting

Sweet potato yield

Cowpea pod number

Cowpea yield

Conclusion and recommendations Sweet potato + 1 row cow pea relay crop had a comparable growth development and yield with the pure fertilized sweet potato. Cow pea yield from sweet potato + 1 row cow peas was also comparable with yield from pure 1 row cow pea and pure 2 row cow peas. Relay cropping sweet potato + 1 row of cow peas is more profitable since the farmer is able to obtain yields from both crops above profit margin.

The Land Equivalent Ratios for sweet potato with 1 row cowpea was 1 2 rows and 1 row pure cowpea rows had 0.388 and 0.385 LER

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