ABSTRACT

This study was aimed at investigating the effect of x-irradiation on growth and yield parameters of four cowpea (Vigna unguiculata (L.) Waip) varieties (Black eye, Dark Brown eye, Ife Brown and Light Brown eye). Fifty seeds each of the varieties were arranged into five groups in a paper envelop and irradiated at five levels ranging from (0, 5, 10, 15 and 20 MGy) respectively at the Radiology Department of the Federal Medical Centre (FMC) Umuahia, Abia State. The growth parameters were recorded at 2, 4, 6, 8, 10 and 12 week after planting (WAP). The field experiment was conducted in a 4x5 factorial experiment in a Randomized Complete Block Design (RCBD) with three replicates at the Teaching and Research farm of Micheal Okpara University of Agriculture Umudike. The parameters measured include days to 50% emergence, plant height, number of leaves, stem girth, leaf area (cm2), number of branches/plant, days to 50% flowering, number of pods/plant, peduncle length, empty pod yield (g), pod length (cm), 100-seed weight (g), seed yield per pod (g), number of seed per pod, grain yield per hectare (t/ha). The result obtained revealed that there was significant increase with increasing doses at (10 MGy and 15 MGy) on the growth parameters as compared to the controls. There was a proportional reduction in days to 50% emergence with respect to treatments on varieties of Black eye (4.8 days at 15 MGy) and Dark Brown eye (5.2 days at 10 MGy) varieties as compared to the control (3.8 days and 3.9 days), while Ife Brown (3.2 days at 5 MGy) and Light Brown eye (8.5 days 10 MGy) varieties were significantly increased by the mutagenic doses as compared to the controls (4.6 days and 11.4 days). The data on days to 50% flowering revealed that the X-ray doses gave rise to shorter days to flowering. Also the X-ray doses of 10 MGy and 15 MGy revealed higher values than other treatments and control on the yield parameters measured. The result so far obtained showed that Light Brown eye at 15 MGy is the best variety in yield (3.6 grain yield per hectare) as compared to other varieties and treatments. It is therefore expedient to mention that x-irradiation induced marked variability among the varieties morphologically as conspicuous tall, early maturing, high yielding and beneficial yield parameters were observed at x-irradiation doses (10 MGy and 15 MGy). The modified traits should be incorporated into breeding programmers for further improvement.