Growth and Yield Response of Groundnut (Arachis hypogyaea L.) to Weeding Regime and Plant Spacing

Field experiments were conducted at the Plantation Section of the Faculty of Agriculture, KNUST, in the major (March) and minor (August) seasons of 2007 and major (May) season of 2008 to determine the growth and yield response of groundnut to weeding regime and plant spacing. The experimental design was a 4 x 3 factorial, arranged in a Randomized Complete Block Design (RCBD) with three replications. The treatments comprised four levels of weeding (No-weeding or control (W0), weeding 2-3 weeks after planting (W1), weeding 3-4 weeks after planting (W2) and W3 or weed-free) and three levels of plant spacing which included 20 cm x 20 cm (250,000 plants/ha), 30 cm x 30 cm (111,111 plants/ha) and 30 cm x 45 cm (74,740 plants/ha)). Normal husbandry treatments including refilling, thinning, fertilizer application, pests and disease control and weeding were undertaken. Response variables measured were growth and yield components. The results of the study indicated that the weed-free treatment significantly (P<0.05) recorded the highest plant height, shoot dry matter, number of branches and nodules per plant. The results also showed that total dry matter, pod and grain yields, number of pods per plant, shelling percentage and harvest index showed significant response (P<0.05) to weeding in both 2007 and 2008. However, the number of seeds per pod did not show any significant effect with weeding in all the three seasons. Similarly, weeding did not significantly (P>0.05) affect hundred seed weight in 2007, but had significant effect (P<0.05) on hundred seed weight in 2008. The highest grain yields of 1034 kg ha-1, 1231 kg ha-1 and 3579 kg ha-1 were produced by the weed-free treatment in March, 2007, August, 2007 and May, 2008, respectively, and were mainly due to the increased number of pods per plant and hundred seed weight. vi Results of the three seasons indicated that total dry matter, pod and grain yields and number of pods per plant were influenced by plant spacing. However, number of seeds per pod, hundred seed weight and harvest index did not show any significant effect (P>0.05) with spacing in all the seasons. The widest spacing (30cm x 45cm) significantly (P<0.05) gave the highest plant height, number of branches, number of nodules, shoot dry matter and number of pods per plant in all the three seasons. The closest spacing (20cm x 20cm) recorded the highest total dry matter, pod and grain yields, shelling percentage, and harvest index, with the highest grain yields being 969 kg ha-1, 967 kg ha-1 and 3449 kg ha-1 in March, 2007, August, 2007 and May, 2008. The weeding treatment showed that total dry matter was positively correlated with seed yield (r=0.948), number of pods per plant (r=0.972), number of seeds per pod (r=0.957) and hundred seed weight (r=0.667). Similarly, total dry matter had positive correlation with seed yield (r=0.972), number of seeds per pod (r=0.920), but negatively correlated with hundred seed weight (r=-0.911) and number of pods per plant (r=-0.922) with spacing treatment. Farmers should adopt the weed-free and the closest spacing treatments since they produced the highest pod and grain yields in the experiment of all the three seasons.

Source: KNUST