This study aimed at assessing the magnitude and nature of genetic variation present in seventeen pro-vitamin A (PVA) maize varieties, investigate the extent of association among agronomic characters responsible for yield and its components in the maize varieties and evaluate the performance of the maize varieties. The field experiment was carried out at the Teaching and Research Farm of the Rivers State University, Nkpolu, Port Harcourt under rain fed conditions in May, 2018 and were laid out in a randomized complete block design with three replications. Data were collected on established plants per plot, days to 50% silking, days to 50% anthesis, anthesis-silking interval, plant height, ear height, final stand count, number of ears harvested, grain moisture content, field weight and grain yield. Results showed significant differences (P < 0.01) among varieties for all traits evaluated. PVASYN-13 had the highest grain yield per hectare among other varieties. High heritability estimates coupled with high genetic advance were observed in established plants per plot, anthesis-silking interval, final stand count, number of ears harvested, field weight and grain yield, an indication of the additive nature of their inheritance. Thus, the presence of variation could serve as basis for selection for yield improvement in maize.

In crop breeding, the selection for yield is made complex because of the quantitative and polygenic nature of the character. This study was undertaken to assess character association and show the contribution of various yield contributing characters in some maize varieties through the help of correlation and path coefficient analyses in order to identify appropriate plant characters for selection to improve maize grain yield. Seventeen maize varieties were sown in a randomized complete block design with three replications in a humid environment of Port Harcourt, Nigeria in 2018 under rainfed condition. Data were recorded for days to 50% anthesis, days to 50% silking, anthesis-silking interval, plant height (cm) and ear height (cm), number of plants per plot, number of plants harvested, number of ears harvested, moisture content (%), field weight (kg), and grain yield (t ha-1). Results showed number of plants per plot, number of plants harvested, number of ears harvested and field weight correlated positively and significantly both phenotypically and genotypically with grain yield. Path coefficient analysis at the genotypic level also revealed field weight and days to 50% anthesis as the characters exerting the highest positive direct effect on grain yield. Therefore, maize grain yield could be improved through indirect selection for these characters.

Farmers in the Niger Delta region of Nigeria only practice rainfed agriculture, partly because of the misconception that the area has abundant rainfall even though the region has distinct wet and dry seasons. This, coupled with the low soil fertility always results in crops being produced at the subsistence level. This experiment was therefore conducted during the dry season to investigate the growth response of fluted pumpkin (Telfairia occidentalis Hook. F) to different combinations of poultry manure and depths of irrigation in a loamy sand soil. It was a randomized complete block design experiment involving three levels each of poultry manure and irrigation with three replications. The treatments comprised random combinations of 10, 20 and 30 t/ha poultry manure with 3, 4 and 5 mm depths of irrigation, including control treatment that had neither manure nor irrigation. Results indicated that the application of poultry manure and irrigation produced significantly higher values of all the growth parameters than the control. Although the combination of 30 t/ha manure and 4 mm depth of irrigation produced the maximum leaf area, the best result in terms of vine length, number of leaves, vine fresh weight and total shoot yield was obtained by combining 30 t/ha manure with 3 mm irrigation depth. This study therefore recommends the application of 30 t/ha poultry manure and 3 mm depth of irrigation for the cultivation of fluted pumpkin during the dry season in the Niger Delta region of Nigeria.

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This study is aimed to evaluate the yield performance of 12 varieties of upland rice and to assess the agronomic traits that contribute to yield performance of these varieties. A 2-year field experiment was conducted in the Teaching and Research Farm of the Rivers State University, Port Harcourt, Nigeria. The twelve varieties which made up the twelve treatments were laid out in a Randomized Complete Block Design (RCBD) and replicated three times. The experimental site was loamy sand, medium acidic with the soil pH reduced in the second cropping season (pH 4.9 in 2012; and pH 4.8 in 2013). The varieties differed significantly amongst themselves in panicle weight, number of fertile spikelets, grain length/breath ratio, 1000 grain weight in 2012 and 2013 planting and grain yield in 2012 planting season. The ITA 321 had the highest yield of 10300.33 kg/ha in 2012 and 10533.33 kg/ha in 2013 followed by NERICA 1 having 9066.67 kg/ha (2012) and 9133.33 kg/ha (2013). The NERICA 2,3,4,5 and 6 also belonged to the high yielding group while APO, Vandana,  IR68 and ITA 150 recorded lower yields. Results of this evaluation have shown that ITA 321 and NERICA 1 can be grown in the tropical rainforest zone for paddy grain yield rather than ITA 150 which are already in use in this agro-ecological zone. They are recommended also for adoption and use in rice production instead of the popular ITA 150.