Effect of Plant Population Density and Methods of Weed Control on The Yield of Pepper ( Capsicum annum L.) in Northeastern Nigeria

Field experiments were conducted at Yola and Garkida in Adamawa State, North-Eastern Nigeria during the 2017 rainy season. In the Yola location the experiment was conducted at the Teaching and Research Farm of the Department of Crop Production and Horticulture, Modibbo Adama University of Technology, Yola, and in Garkida it was conducted at Garkida village in Gombi Local Government Area of Adamawa State. The experiment was designed to study the effect of plant population density and methods of weed control on the yield of pepper (Capsicum annum L.). The treatments consist of three spacings, 25 x 30cm, 35 x 40cm and 45 x 50cm with four (4) different herbicides rates (No herbicide, pyrithiobac sodium 65.5kg a.i/ha, pendimethalin 1kg a.i/ha + pyrithiobac sodium 65.5kg a.i/ha and Haloxyfop 108g a.i/ha + hand hoe weeding. The experimental design was a split-plot design replicated three times. Spacing was assigned to the main plot while methods of weed control as subplots. Parameters measured were weed density, number of pepper fruits per plot, and fruit yield per hectare. All data were subjected to analysis of variance (ANOVA) appropriate to the split-plot design. The results of the experiment showed that herbicide pyrthiobac sodium 65.5kg a.i/ha recorded the highest number of fruit per plot of 72.4 while herbicide haloxyfop 108g a.i/ha followed by hand weeding recorded the least number of fruits of 50.1. The result of the experiment shows that there was a significant effect on spacing in both locations. Concerning yield per hectare spacing 25x30cm obtained the highest yield per hectare of 945kg in Garkida, while the least was from the Yola location which recorded 537kg. It was concluded that pepper yield depends on the proper spacing and proper use of herbicide which will suppress weed and increase yield significantly

Resistance of cowpea [Vigna unguiculata (l.) Walp.] to Striga gesnerioides (Willd.) Vatke, a parasitic angiosperm

An in vitro growth system was used to investigate the expression of resistance of cowpea [Vigna unguiculata (L.) Walp.] varieties B301 and 58-57 to the angiosperm parasite Striga gesnerioides (Willd.) Vatke. Variety Blackeye was included in experiments as a susceptible control. Seeds of S. gesnerioides germinated on the roots of all varieties. Two different mechanisms of resistance were expressed in B301 and 58-57 after penetration of host roots by parasite radicles. The first mechanism was expressed in both varieties; host tissue around invading Striga radicles became necrotic in association with the early death of the parasite and lack of tubercle formation. On variety 58-57, the necrosis response was expressed only when the roots were inoculated with Striga from Burkina Faso but Striga from Mali successfully parasitized the roots of variety 58-57. The second mechanism was observed only on variety B301. Striga radicles infected cowpea roots, tubercles were formed but remained at 1-2 mm in diameter with very limited stem growth. No further development of the parasite occurred in vitro or when infected cowpeas were grown in soil or vermiculite. Similarities between the expression of resistance of cowpea to Striga and of plants to plant pathogenic fungi are discussed