African Journal of Crop Science

African Journal of Crop Science ISSN 2375-1231 Vol. 6 (8), pp. 001-008, August, 2018. © International Scholars Journals

Full Length Research Paper

Determination of genetic variability for physiological traits related to drought tolerance in African rice (Oryza glaberrima)

Isaac Kofi Bimpong^1,2*, Rachid Serraj¹, Joong Hyoun Chin¹, Evelyn M.T. Mendoza³, Jose Hernandez³ and Merlyn S. Mendioro³

¹Plant Breeding and Biotechnology Division, International Rice Research Institute (IRRI), Los Baños 4030, Laguna, Philippines.

²Africa Rice Sahel Station, BP 96. St. Louis Senegal.

³University of the Philippines Los Baños (UPLB), Los Baños, Pili Drive, College, Los Baños 4031, Philipines.

Accepted 20 March, 2018

Abstract

Relative water content, water potential and transpiration of Africa rice (Oryza glaberrima) were investigated in a controlled condition under phytotron. Two Oryza sativa cultivars, IR55423-01 (a drought tolerant genotype) and IR64 (drought sensitive genotype) and 8 O. glaberrima accessions were grown under droughted and watered conditions. The fraction of transpirable soil water (FTSW) was used as an indicator of water availability. Transpiration was determined by changes in daily pot weights and the ratio of transpiration of droughted to watered plants expressed as normalized transpiration ratio (NTR). The FTSW was greater in O. glaberrima accessions CG14, RAM118 and RAM 152 than all the O. sativa checks; suggesting that they might have the capacity to close their stomata earlier in response to drought stress, in other to keep transpiration rate similar to the rate of uptake of soil water resulting in maintenance of the water balance of the plant. RAM 3 had the greatest dehydration tolerance and some accessions such as RAM 134, RAM152 and RAM163 had lower dehydration tolerance than RAM 3, CG 14 and IR55423-01’ but survived longer suggesting that other avoidance mechanisms such as leaf movement and reduction of leaf area complemented these traits and enhanced their survival. In general, it is necessary to keep FTSW above 0.53, in order to keep transpiration and plant water status high in preventing reduction in dry matter production which will lead to higher yields.

Key words: Drought tolerance, O. glaberrima, O. sativa, fraction of transpirable soil water (FTSW), dehydration tolerance.

African Journal of Crop Science ISSN 2375-1231 Vol. 6 (7), pp. 001-007, July, 2018. © International Scholars Journals

Full Length Research Paper

Segregation of selected agronomic traits in six S₁ cassava families

Kawuki, R. S.^1,2*, Nuwamanya E.¹, Labuschagne, M. T.²,  Herselman L.² and Ferguson M. E³

¹National Crops Resources Research Institute (NaCRRI), P. O. Box 7084, Kampala, Uganda.

²Department of Plant Sciences, University of the Free State, P. O. Box 339, Bloemfontein, 9300, South Africa.

³International Institute of Tropical Agriculture (IITA), P. O. Box 30709, Nairobi, 00100, Kenya.

Accepted 22 March, 2018

Abstract

Inbreeding of predominantly cross-pollinating crops is expected to result in the generation of progeny with reduced fitness and/or progeny with improved phenotypes. However, this effect is not well documented in cassava (MANIHOT ESCULENTA Crantz). In this study, S₁ progeny from six cassava genotypes (I92/00067, TMS 30572, 95/SE-00036, NASE 4, MH95/0469 and Bamunanika) were examined for five traits: fresh root yield (FRY), fresh foliage yield (FFY), harvest index (HI), root dry matter content (DMC) and amylose content in order to study the effects of inbreeding on these traits. Considerable variations were observed among S₁ progeny for FRY (0.0 - 4.3 kg plant^-1); FFY (0.2 to 10.2 kg plant^-1); HI (0.00 - 0.69); DMC (11.0 - 42%) and amylose content (11.8 to 34.2%). Moreover, in each trait, individual S₁ clones existed that substantially outperformed the non-inbred parents. This was particularly true for amylose content where individual S₁ clones in each family had higher amylose content than their respective non-inbred parent. Nevertheless, with introduction of inbreeding an average reduction of 61, 33.8, 24.6 and 13.2% was observed for FRY, HI, FFY and DMC. These results demonstrate that with introduction of inbreeding in cassava, it is possible to generate improved phenotypes, which should be the focus of breeders.

Key words: Amylopectin content, cassava inbreeding, inbreeding depression, Manihot esculenta.

African Journal of Crop Science ISSN 2375-1231 Vol. 6 (7), pp. 001-006, July, 2018. © International Scholars Journals

Full Length Research Paper

Genetic variability, stability and relationship among some Cowpea, Vigna unguiculata (L.) Walp breeding lines

Adeigbe, O. O.^1,2* Adewale, B. D.¹ and Fawole, I. O.²

¹Crop Improvement Division, Cocoa Research Institute of Nigeria, Ibadan, Nigeria.

²Department of Crop Protections and Environmental Biology, University of Ibadan, Ibadan, Nigeria.

Accepted 07 April, 2018

Abstract

The contribution of cowpea to food security in the sub-Sahara Africa is incontestably obvious. Ten genotypes of cowpea were evaluated in different environments to assess their variability and stability. The genotypes differed significantly (P≤0.05) with respect to all the eight phenotypic traits studied. Days from planting to first flower production and to first ripe pod showed the least coefficient of variations (CV) in all environments. The number of branches per plant consistently had the highest genotypic and phenotypic CV in all the three environments. The mean proportion of the phenotypic variation due to genetics was 92.9%. The ten genotypes varied considerably in their stability for the studied morphometric traits. The most stable genotype for days to first flowering (DFF) and days to first pod ripening (DPRP) was IBS9193. However, 25026-2 and 24893-2 were most stable for pod length (PL) and peduncle length (PDL), respectively. Significant genetic and phenotypic correlation existed among the variables; implying typical association among the tested traits. For example, the number of pods per plant negatively but significantly (P≤0.01) correlated with DFF and DPRP. This study indicated that a meaningful selection of genotypes is possible for multi-trait improvement through hybridization.

Key words: Heritability, stability, selection, variances, correlation coefficients.

African Journal of Crop Science ISSN 2375-1231 Vol. 6 (6), pp. 001-009, June, 2018. © International Scholars Journals

Full Length Research Paper

Amylopectin molecular structure and functional properties of starch from three Ugandan cassava varieties

Mufumbo Raphael^1,2, Baguma Yona²*, Kashub Stephen², Nuwamanya Ephraim², Rubaihayo Patrick¹, Mukasa Settumba¹, Hamaker Bruce³ and Kyamanywa Samuel¹

¹Department of Crop Science, Makerere University Kampala, P. O. Box 7062, Kampala, Uganda.

²National Crops Resources Research Institute (NaCRRI), P. O. Box 7084, Kampala Uganda.

³Purdue University, Department of Food Science and Whistler Center for Carbohydrate Research,West Lafayette, IN 47907-2009, USA.

Accepted 04 April, 2018

Abstract

Amylopectin molecular structure is a very important determinant of starch functional properties. The main purpose of this study was to determine the strength of the relationship between the amylopectin structure of starches from cassava varieties and their functional properties. TME14 had the highest (46.63%) proportion of A chains while Bamunanika had the lowest 42.27%. Bamunanika had the highest (23.33%) proportion of B3⁺ chains while TME14 had the lowest 19.66%. TME14 had the highest amylopectin molecular weight 2.74x10⁸ g/mol while NASE10 had the lowest 2.42x10⁸ g/mol. TME14 had a higher gelatinisation temperature 65.37°C compared to the other varieties. Bamunanika had the highest final viscosity 2477.66 mPa s while NASE10 had the highest set back viscosity (494.50 mPa s). TME14 had the highest pasting temperature 67.80°C while NASE10 had the lowest 65.23°C. There was a significant negative correlation between final viscosity and A chains (r = -0.64), pasting temperature and A chains (r = - 0.77), A, B1 chains and gelatinisation temperature of retrograded starches (r = - 0.82, r = - 0.87), respectively, gyration radius and onset temperature of gelatinisation for the retrograded starch (r -0.56) and a significant positive correlation between B2 chains and pasting temperature (r = 0.94), amylopectin molecular weight and percentage retrogradation (r = 0.66). These findings revealed possible improvement through breeding for starch with desired qualities.

Key words: Amylopectin structure, cassava varieties, functional properties.

African Journal of Crop Science ISSN 2375-1231 Vol. 6 (6), pp. 001-003, June, 2018. © International Scholars Journals

Short Communication

Floral biology of Bambara groundnut [Vigna subterranea (L.) Verdc]

N. C. Onwubiko¹*, M. I. Uguru², A. A. Ngwuta¹, E. T. Inyang¹ and O. J. Nnajiemere¹

¹Department of Crop Science and Technology, Federal University of Technology, Owerri, Imo State, Nigeria.

²Department of Crop Science University of Nigeria, Nsukka, Enugu State, Nigeria.

Accepted 07 March, 2018

Abstract

Investigation on floral biology of twelve accessions of Bambara groundnut [Vigna subterranea (L.) Verdc] was carried out in the greenhouse of the School of Agriculture and Agricultural Technology, Federal University of Technology, Owerri, Nigeria, in a completely randomized design with three replications. Significant varietal differences (P<0.05) were observed among the accessions in all characters investigated except for age of germination (P>0.05). Typical of flowering plants, the crop consists of vegetative and reproductive organs. The initiation of flower buds was between 30 and 48 days after planting (DAP) while the maturity of the flowers was between 34 and 52 DAP (3 to 5 days from flower bud initiation). Matured flowers for hybridization should be 2 to 3 days old from bud initiation and observed to be yellow or creamy in colour. The time taken for matured flower bud to open (anthesis) ranged between 12 to 20 h (which occurred between 07:00 and 10:00 h). Emasculation should be carried out on mature flower buds within 12 h of flower bud maturity as pollination takes place after this period.

Key words: Floral biology, bambara groundnut, Vigna subterranea.