Investigation was conducted on the effects of early weed removal on some yield attributes of Zea mays L. var. TZB (FARZ 34) cultivated in Owerri, Nigeria with the aim of evaluating the extent of reduction in total output occasioned by delays in weed removal following seed sprouting. Healthy seeds of this variety were obtained from State Agricultural Development Corporation. The seeds were sown onto manually prepared plots in a Completely Randomized Design. Weeds on treated subplots were removed ten day following germination while those growing on the other plots (untreated) were not removed until 30 days after germination. Data on yield attribute parameters such as number of marketable cobs per plant, green earlength of undehusked cob, thousand grain weight etc. were collected. Results showed that difference in number of cobs per plant between crops harvested from treated and untreated subplots was statistically significant p<0.01. Other yield attributes investigated gave similar results with varying degrees of percentage yield differences between crops from treated and untreated subplots. The implication of this is that Zea mays competitive capability with weeds at early vegetative stages was inadequate comparable to that of the weeds. Incorporating early weed removal in the total farming plan will result in substantial yield gain for growers.
In the present investigation, in vitro propagation of Jatropha curcas L. was achieved employing nodal explants. Axillary shoot bud proliferation was best initiated on Murashige and Skoog’s (MS) medium supplemented with 20 μM N6-benzyl- adenine (BA) and 50 μ M adenine sulphate, in which cultures produced 8.2 ± 0.56 shoots per nodal explant with 3.0 cm length after 3-5 weeks. The rate of shoot multiplication was significantly enhanced after transfer to MS medium supplemented with 2.5 μ M 6-furfuryl amino purine (Kn), 0.5 μ M indole- 3-butyric acid (IBA) and 25 μ M adenine sulphate for 4 weeks. Internode explant segments of Jatropha curcas plants responded in vitro and formed callus tissue when cultured on Murashige-Skoog (MS) full strength nutrient medium supplemented with 2,4-Dichlorophenoxyacetic acid (2,4-D – 4 mg/L) and N6-Benzyl adenine (BA- 4 mg/L). The internode-derived callus tissues were found non-embryogenic and hence did not regenerate into shoot and root, respectively. The internode segments when cultured on MS (full strength) media supplemented with BA – 5 mg/L) were found to grow forming two to three buds. However, these shooting explants did not form roots upon hormonal regulation. On the contrary, endosperm tissue cultured on full strength MS media supplemented with 3 mg/L BA and 1 mg/L Indole-3-butyric acid (IBA) along with activated charcoal (100 mg/L) and ascorbic acid (50 mg/L) yielded simultaneous shooting and rooting response after four weeks of incubation.