Open Access Minireview Article

Prediction of Heterosis in Crop Plants – Status and Prospects

Passoupathy Rajendrakumar, Krishna Hariprasanna, Nadoor Seetharama

Journal of Experimental Agriculture International, Page 1-16
DOI: 10.9734/AJEA/2015/19263

Heterosis has been commercially exploited in many crops; however, its genetic and molecular basis is still not clear. The availability of advanced genomic tools has encouraged several research groups to dissect heterosis into genetic components. Prediction of heterosis using molecular markers is the first step towards this direction, as it may lead to the identification of markers and genomic regions associated with heterosis. Practically, it increases the efficiency of hybrid breeding by marker-assisted selection of superior parental combinations without large-scale field evaluation. Extensive studies in important crops like rice, wheat and maize have identified the genes / genomic regions associated with heterosis and also demonstrated the potential of molecular prediction. Recent trends in whole transcriptome and metabolome analyses will help in the identification of genes or metabolic networks involved in the expression of heterosis. Various genomic tools such as heterotic loci, molecular markers associated with heterotic gene blocks, ESTs and heterosis-related gene databases provide better opportunities for understanding the molecular basis of heterosis and to develop reliable methodologies for a realistic prediction of heterosis. This review provides critical analysis of the prediction of heterosis in crop plants and its implications in hybrid development

Open Access Original Research Article

Weight Gain and Cost Benefit of West African Dwarf Goats Fed Pleurotus tuber-regium Biodegraded Cassava (Manihot esculenta) Peels Based Diets

R. E. Barde, S. Attah, A. Wuanor, U. Okpanachi

Journal of Experimental Agriculture International, Page 1-8
DOI: 10.9734/AJEA/2015/17417

Aims: To determine the growth gain and cost benefit of West African Dwarf (WAD) goats fed diets containing white rot fungi (Pleurotus tuber-regium) biodegraded cassava peels based diets.

Study Design: Completely randomized designed experiment.

Place and Duration of Study: The study was conducted at the ruminant farm Unit of the College of Agriculture, Lafia, Nigeria located Latitude N08°29′8.66′′; Longitude E08°29′49.10′′and Altitude 164.5 m; in the guinea savannah vegetation. The experiment lasted for 84 days.

Methodology: Twenty intact WAD bucks of aged between 7-9 months and weighing on the average 6.17±0.96 kg were randomly allocated to five treatment diets (T1-T5) containing untreated cassava peels (UCPS) and  Pleurotus tuber-regium biodegraded cassava peels (PT-CPS) compounded as follows: T1 – 100% untreated cassava peels (UCPS), T2 – 100%  Pleurotus tuber regium  treated Cassava Peels (PT-CPS). T3 – 75% UCPS + 25% PT-CPS. T4 – 50% UCPS + 50% PT-CPS and T5 – 25% UCPS + 75% PT-CPS. Daily feed intake, weekly weight gain, feed conversion ratio, benefit, cost and cost benefit ratio were evaluated.

Results: Weight gain of WAD bucks fed treatment diets showed significant (P = .05) final weight of 13.25 kg by bucks fed 100% PT-CPS diet (T2), and the lowest 8.00 kg for 100% UCPS. Bucks onT2 diets also recorded the highest (P = .05) total mean weight gain of 7.08 kg while bucks on control T1 diet had 1.73 kg as total mean weight gain. Weekly feed intake by the bucks were equally highest (P = .05) for bucks in T2 (1,749.75 g) and lowest for bucks in T1 (1,501.13 g). Cost per kg feed consumed recorded a significant (P = .05) N50.66 for 100% PT-CPS diet. Benefit cost ratio (BCR) showed a superior (P = .05) 3.38 for bucks fed 100% PT-CPS diet (T2) and lowest BCR value of 0.91 obtained for bucks fed 100% UCPS diet (T1); inferring treatment T1 is not worth adopting. It was concluded that incorporation of 100% of cassava peels (45% of the diet) biodegraded by Pleurotus tuber-regium for 21 days had potential economic gain in growing West African Dwarf goats.

Open Access Original Research Article

Managing Sclerotinia Blight in Peanut: Evaluation of a Weather-based Forecasting Model to Time Fungicide Applications in Texas

J. E. Woodward, S. A. Russell

Journal of Experimental Agriculture International, Page 1-9
DOI: 10.9734/AJEA/2015/19395

Aim: To evaluate fungicide regimes were applications were made according a weather-based disease advisory compared to current application timings.

Study Design: Randomized complete block with four replications.

Place and Duration of Study: Studies were conducted during the 2008, 2009 and 2010 growing seasons on a producer farm located near Seminole Texas, Gaines County in fields with a history of Sclerotinia blight.

Methodology: Fungicide applications were made using a weather-based spray advisory model with varying Five-day risk index (FDI) thresholds that were calculated from daily average soil temperature, rainfall/irrigation and growth development. Five FDI treatments, a calendar-based and symptom-based (positive controls), as well as a non-treated (negative control) were evaluated. The cultivars Flavor Runner 458, Tamrun OL 02 and/or Tamrun OL07 were utilized in this study based on their differing reactions to Sclerotinia blight. Disease control, yield and quality for these timings were compared to the calendar-based and symptom-based programs, as well as the non-treated control.

Results: Appreciable levels of Sclerotinia blight were observed in 2008 and 2010. The application of fungicides led to a decrease in disease incidence compared to the non-treated control; however, few differences were observed among fungicide treatments. Overall, higher yields were achieved when fungicides were applied according to the calendar-based program. Similar yields were generally achieved for the lowest of the FDI thresholds evaluated and yields were generally lower when applications were delayed due to higher FDI thresholds. Grades were not affected by fungicide treatment; however, differences between cultivars were observed. Flavor Runner 458 consistently had higher grades than Tamrun OL07; however, Tamrun OL07 has improved resistance to S. minor.

Conclusion: Results from these studies suggest that the weather-based spray advisory model evaluated herein was not effective at improving upon the efficacy of fungicides for control of Sclerotinia blight in peanut. Moreover, applications for control of the disease in Texas should be made approximately 70 to 75 days after planting with a sequential application being made 28 to 30 days later.

Open Access Original Research Article

Micro-Dosing of Inorganic Inputs on Maize Production on an Acid Soil in Kenya: An Agronomic and Economic Evaluation

P. O. Kisinyo, P. A. Opala, S. O. Gudu, C. O. Othieno

Journal of Experimental Agriculture International, Page 1-9
DOI: 10.9734/AJEA/2015/17984

Aims: The study determined the effect of micro-dosing of lime, P and N fertilizers on maize grain yield and economic benefits.

Study Design: The experiment was a 2 x 2 x 3 split-split plot laid out in randomized complete block design with N (0 and 37.5 kg N ha-1) in the main plot, P (0 and 13 kg P ha-1) in the sub-plot and lime (0, 0.77 and 1.55 tons lime ha-1) in sub-sub plot. 37.5 kg N and 13 kg P ha-1 are 50% of the recommended fertilizer rates for maize production in Kenya while 0.77 and 1.55 tons lime ha-1 are 25 and 50% of the actual requirement.

Place and Duration of Study: The study was carried on nutrient deficient acid soil on a small holder farmer (SHF) field in Busia County, Kenya during the years 2008 and 2009.

Methodology: Lime was applied once during the long rain in the year 2008 while P and N fertilizers each cropping season.

Results: Grain yield increased by 148 and 40% due to 50% of both the recommended N and P fertilizers, respectively and 5-17% due to 25-50% of the lime requirement. Majority (57-75%) of the production costs were due to inorganic inputs. Only combined application of 50% of both the recommended N and P fertilizers produced economically viable returns throughout the cropping period. Combination of 50 and 25% of the recommended P and lime, respectively and 50 and 25% of the recommended N and lime, respectively produced economically viable returns only during the second and third cropping seasons. A combination of 50% of both the recommended P and lime produced economically viable returns during the third cropping season only.

Conclusion: Small holder farmers producing crops on Kenya’s acid soils deficient in N and P such as in Busia County can realize economically viable returns by micro-dosing of N, P fertilizers and lime.

Open Access Original Research Article

Genetic Variability and Association of Traits in Mid-altitude Sesame (Sesamum indicum L.) Germplasm of Ethiopia

Mohammed Abate, Firew Mekbib, Amsalu Ayana, Mandefro Nigussie

Journal of Experimental Agriculture International, Page 1-14
DOI: 10.9734/AJEA/2015/18483

Aim: The study was carried out to assess the genetic variability and association of traits with respect to seed yield and its components in (mid-altitude) sesame germplasm of Ethiopia.

Study Design: A 9 x 9 Simple Lattice Design (SLD) with two replications was used.

Place and Duration of Study: Melkassa Agricultural Research Centre Ethiopia, during the July-December, 2011 main cropping seasons.

Methodology: The data recorded on 14 quantitative traits were analyzed for phenotypic and genotypic coefficient of variances, heritability and genetic advance, correlation coefficient, path coefficient analysis, principal component analysis and divergence analysis based on Mahalanobis statistics, using SAS 9.2. Statistical software to evaluate the pattern and extent of variation among 81 mid-altitude genotypes. 

Results: Analysis of variance revealed significant difference among genotypes for all traits studied. Less than 50% heritability was noted in all traits studied. Moderate heritability coupled with moderate to high genetic advance was recorded for most of yield related traits, indicating that these traits are controlled by both additive and non-additive genes. Characters viz., number of capsules, biomass yield, harvest index and 1000 seed weight showed highly significant positive correlation with seed yield. Maximum positive direct effect on seed yield was exerted by number of capsules, biomass yield, days to maturity and harvest index, showing that these traits can be used for selection to improve the primary trait. Divergence analysis based on Mahalanobis statistics grouped the genotypes into seven different clusters. Genotypes were not grouped in relation to their geographical distribution. Maximum inter cluster distance was observed between cluster V and VII; hence, genotypes from these two clusters are suggested as parents for hybridization program to achieve promising recombinants.

Conclusion: The germplasm lines had sufficient level of genetic variability for seed yield and its components. Clustering was not associated with the geographical distribution instead genotypes were mainly grouped due to their morphological differences. Seed yield, biomass/plant, harvest index and number of capsules contributed highest towards genetic divergence. The use of these traits in sesame improvement program would increase yield.

Open Access Original Research Article

Distribution of Cassava Mosaic Geminiviruses and their Associated DNA Satellites in Kenya

F. M. Mwatuni, E. M. Ateka, L. S. Karanja, S. K Mwaura, I. J. Obare

Journal of Experimental Agriculture International, Page 1-12
DOI: 10.9734/AJEA/2015/18473

A countrywide survey was conducted to determine the distribution, incidence, prevalence and severity of cassava mosaic disease (CMD) and the associated DNA satellites in Kenya. Disease transmission either by whitefly or infected cuttings was evaluated. PCR detection method was used for the detection of these viruses and the associated DNA satellites. CMD was widely distributed in the country with an average incidence of 57%, whereas Coast province recorded the highest incidence (74%). The prevalence of CMD countrywide was 84% with Nyanza province recording the highest (96%), whereas Eastern province had the least (67%). The spread of CMD through use of infected cuttings accounted for 80% of the infected plants compared to the whitefly-borne infections which accounted for 19%. East African Cassava Mosaic Virus (EACMV) and African Cassava Mosaic Virus (ACMV) accounted for 51% and 20% of samples, respectively. Co-infection of cassava plants with the two viruses was detected in only 9% of the samples. EACMV was detected in samples collected from all the provinces surveyed. ACMV was mostly prevalent in Western and Nyanza provinces. For the first time, ACMV was detected in Eastern and Coast provinces. Nyanza province had the highest whitefly count per plant with Western province registering the least. The method of transmission of CMD was mainly through use of infected cassava cuttings with 100% transmission by stem cuttings in Coast province. DNA satellites associated with these Begomoviruses were distributed across the country with 41% of samples testing positive. The symptom severity in plants infected by Cassava Mosaic Geminiviruses (CMGs) and the associated DNA satellites were higher compared to those infected with CMGs only. There is need for the identification of varieties resistant to these viruses. The begomovirus symptom modulation by the DNA satellites need to be further investigated to determine effects on disease severity and yield of cassava

Open Access Original Research Article

Environment and Some Adopted Agronomic Practices- Grassroots’ Participation in Osun and Ondo States of Nigeria

Wasiu Agunbiade Lamidi, A. Solomon Adeyeye

Journal of Experimental Agriculture International, Page 1-10
DOI: 10.9734/AJEA/2015/19226

The effects of adoption of improved sustainable agricultural practices in crops by grassroots’ farmers were studied in Osun and Ondo States of Nigeria, among 30 large-scale commercial farmers in each state. Different types of sustainable practices namely organic agriculture (ORM); agri-horti-silviculture (AHS) and combined polyculture and permaculture (CPP), common to farmers in the area were evaluated. Different parameters measured were plant population of trees, estimated number of pods, time of fruiting/maturity, number of cobs/maize/bunch/leaves and others alike. Simple correlation, regression analysis, percentiles and one way-ANOVA statistic were used for data analysis. The results revealed that there was a significant effect (P < 0.05) of the different sustainable practices on the yield of the crops planted. Root and stalk lodging, flower/fruits abortions were high especially in the CPP and AHS plots than ORM. There were stronger relationships between independent variables, different sustainable practices and yields of maize with higher R2 value of 0.99. There was less than 5% awareness among farmers with such adoptable farm practices. Some diseases were not controllable as reported by 91.67% of the farmers. Also, 33.3% of the farmers concluded that tillage operations were delayed than before. There was significant (p< 0.05) effect of different adopted processes on the number of plants’ stand and on the number of crops that had fruits’ and flowers’ abortions. Various agronomic practices improve soil and farm operations with positive impact on farmers’ livelihood