African Journals Online
Ghana Journal of Agricultural Science

VOLUME 30 (1997) PART ONE
Abstracts

APPLICATION OF A SIMPLE CROP PHYSIOLOGICAL MODEL BASED ON SOME YIELD DETERMINANTS TO ASSESS THE PRODUCTIVITY OF PIGEONPEA GENOTYPES IN NORTHERN GHANA

(K.O.M.: Savanna Agricultural Research Institute, P.O. Box 52, Nyankpala, Tamale, Ghana; F.W.: International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Bamako, Mali; W.P.: International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Sahelien Center, Niamey, Niger)

Pigeonpea (Cajanus cajan (L.) Millsp.) is cultivated in northern Ghana mainly on marginal soils towards the end of the rainy season. The crop, therefore, subsists on residual soil moisture for most part of its growth. Little is known, however, about varieties best adapted to this zone under such harsh conditions.

Twenty early-maturing pigeonpea lines were, therefore, evaluated in the northern Guinea savanna

ecology of Ghana with the objective of determining the physiological basis of their yields. Grain yields

(Y), reproductive development (RD), total biomass (T), crop growth rates (CGR), harvest indices (HI) and the rate of partitioning (p) of photosynthates to reproductive sinks were estimated. Wide variations

were observed for pod yields and the yield determinants. No direct links were observed between

RD and the other parameters. However, there were close correlations between grain yield, T, CGR, HI and p on the other. The possibility of developing genotypes which combine high grain yield, T, CGR, HI and p in a single genetic background is, therefore, achievable. Genotypes with such attributes are most desirable to produce grains for human consumption and fodder for livestock. This study provides an example of how a simple physiological model can enhance the selection efficiency of plant breeders, through a better understanding of the genetic materials that are handled.

Original scientific paper. Received 16 Jul 96; revised 6 Jan 97.

School of Agriculture, University of Cape Coast, Cape Coast, Ghana

Two experiments were carried out firstly to study the processes of development and tuber initiation in cassava seedlings, and secondly, to determine the appropriate age at which cassava seedlings should be transplanted to ensure optimum field establishment and higher yield. In the first experiment, nursed seedlings were uprooted at weekly intervals from time of emergence for 9 weeks, and observed for root and shoot development. Transverse sections of roots were examined for the presence of starch grains. In the second experiment, seedlings at 27, 34, 41 and 48 days old were transplanted (naked root) to the field and observed for survival and tuber yield after 10 months of growth. Most seeds germinated within 7-16 days after sowing but a few germinated after 70 days. During the first 9 weeks of seedling growth, an average of three leaves unfolded every week on the main stem. Stem elongation occurred at a fairly constant rate of 5.1 mm /day while tap root elongation was 8.6 mm/day for the first week, and 2.4 mm/day over the next 6 weeks. Lateral root elongation was high, averaging about 9.3 mm/day over the first 6 weeks of growth. Starch grains were first observed in the tap root at 4 weeks and in the lateral root tissues at 5 weeks. Proliferation of starch-filled cortical cells began in the tap and lateral roots at 5 and 9 weeks respectively. Percentage survival were 28, 63, 80, and 67 for seedlings transplanted at 27, 34, 41 and 48 days old respectively. Tuber yield ranged from 6525 kg/ha for the 27 days old seedlings to 17 764 kg/ha for the 41 days old seedlings. It was concluded that the most appropriate age at which to transplant cassava seedlings to ensure optimum survival and yield was 41 days after sowing.

Original scientific paper. Received 28 Mar 96; revised 9 Jan 97.

(K. O. M.: Savanna Agricultural Research Institute, P. O. Box 52, Nyankpala, Tamale, Ghana; F. W.: International Crops Research Institute, B. P. 320, Bamako, Mali)

A simple crop physiological model was employed to study the yield basis and environmental effects on 31cowpea genotypes of early, medium and late maturities. The tests were carried out at four sites in northern Ghana between 1992 and 1994. Genotypic variations observed for pod yields (Y), reproductive duration (RD), crop growth rates (CGR) and partitioning coefficients (p) were wide. Pod yields averaged 2032, 2170 and 1983 kg ha-1 for the early, medium and the late lines, respectively. The interaction effects of years with genotypes were quite substantial for pod yield and all the other physiological parameters. Partitioning coefficient was more stable than pod yields in the medium and late lines as shown by the non-significant interactions of genotype W location effects. Regression of pod yields and partitioning coefficients with their respective environmental means also showed the latter to be more stable. Plant breeders may, therefore, put selection pressure on p when developing cowpea varieties for the Guinea and Sudan savanna agro-ecological zones, because of its relative stability compared with pod or grain yields. Pod yields correlated with p in all the maturity groups. CGR correlated better with Y for medium and late lines than the early genotypes. This indicates good possibilities for identifying lines which canproduce both haulms for livestocks and pods for human consumption in the medium and late lines.

Original scientific paper. Received 25 Jul 96; revised 23 Jan 97.

K. Ofori-Frimpong, D. L. Powell & M. R. Appiah 

(K. O.- F. & M.R.A.: Cocoa Research Institute of Ghana, P. O. Box 8, Tafo-Akim, Ghana; D.L.P.: Department of Soil Science, University of Reading, P. O. Box 233, Reading, RG6, England)

Changes in the forms of phosphorus present in Ghanaian cocoa- growing soils incubated at 25 oC for up to 56 days in the presence of added cocoa leaf litter and/or phosphorus fertilizer are described. The addition of organic litter alone had little effect on bicarbonate-extractable inorganic phosphorus but large initial increase of the inorganic phosphorus occurred with the litter and phosphorus fertilizer added in combination, followed by a decrease especially in the phosphorus deficient soils. The addition of the litter without phosphorus fertilizer increased microbial biomass phosphorus content in all the soils, the increase being between 15 and 70 per cent in the soils without the litter addition and thus suggesting that the litter, among others, might be a possiblesource of the increased microbial biomass phosphorus in these soils. When litter and phosphorus fertilizer were added together, there was an initial rapid incorporation of phosphorus into the microbial biomass in the soils with low initial available phosphorus content. The phosphorus content of the microbial biomass should, therefore, be considered in determining the trend of organic phosphorus mineralization in soils.

Original scientific paper. Received 11 Mar 96; revised 31 Jan 97.

SMALL HOLDER LAMB FATTENING BASED ON CROP RESIDUES AND AGRO-INDUSTRIAL BY-PRODUCTS IN NORTHERN GHANA

(N.K. & J.B.: Animal Research Institute, CSIR, P.O. Box 52, Nyankpala-Tamale; W.S.A.: CSIR Secretariat, Accra; S.A.A.: Ministry of Food and Agriculture, Animal Production Department, Pong-Tamale)

In an on-farm study involving four sedentary mixed-farming communities in the Savelugu-Nanton District, a total of 29 intact rams (DjallonkeW Sahelian) were fattened on two diets formulated from rice straw (urea-treated), pigeon pea waste, dry cassava peels and whole cottonseed. In Diet 1, cassava peels constituted the basal ingredient while in Diet 2, pigeon pea waste was major. Total daily dry matter (DM) intakes by rams were 958.0 and 852.3 g/head for Diet 1 and 2 respectively. Both diets supported appreciable body weight gain. Diet 1 appeared superior and ensured a significantly (P<0.01) higher average daily weight gain (ADG) of 130.0 g compared to 87.9 g recorded for Diet 2. Animals on

Diet 1 had a feed efficiency ratio of 7.3 kg DM/kg gain as against 9.7 kg DM/kg gain by Diet 2. Economic considerations of the diets fed per ram indicated daily feed bills of "36.93 and "32.16 for Diet 1 and 2 respectively. The calculated profit margins per unit animal fattened were positive for both dietary options. The cassava peel-based option (Diet 1) yielded a profit margin 80 per cent higher than the pigeon pea waste-based diet (Diet 2).

Original scientific paper. Received 21 Mar 96; revised 18 Feb 97.

AGRONOMIC PERFORMANCE OF SEVEN VARIETIES OF ALFALFA (MEDICAGO SATIVA L.) IN THE COASTAL SAVANNA ZONE OF GHANA

School of Agriculture, University of Cape Coast, Cape Coast, Ghana

Seven varieties of alfalfa, namely Iroquois, Vernal, Mohawk, Pike F0185, WL 318, Oneda and WL 514, were screened for agronomic performance at Cape Coast in the coastal savanna ecological zone of Ghana during the period from May 1992 to May 1993. A total of 10 harvests were taken at monthly intervals after 3 months of initial growth. Significant differences (P < 0.01) were established among the varieties for dry matter yield, leaf-stem-ratio, rate of regrowth after cutting, and flowering ability. Total dry matter yields for the 10 cuts ranged from 21 049 kg/ha for Mohawk to 24 171 kg/ha for WL 318. Dry matter yield at each cut varied considerably over the year. The highest yields of 3 100 to 3 700 kg/ha/cut were obtained during the second cut in October and the least yields of 1490 to 1650 kg/ha were obtained during the sixth cut taken in January. When left to overgrow, percentage of plants that flowered ranged from 11.3 for Mohawk to 67.5 for WL 318. Again two types of insects, honey bees and the blow fly Calliphora spp., were observed to effectively trip the flowers.

Original scientific paper. Received 28 Mar 96; revised 12 Mar 97.

School of Agriculture, University of Cape Coast, Cape Coast, Ghana

Studies were carried out at the Teaching and Research Farm of the University of Cape Coast, in the minor seasons of 1992 and 1993, to assess the agronomic potential of some common agricultural wastes as surface mulches in terms of weed control, nematode population in soil, root-knot incidence and growth and yield of pepper (Capsicum frutescens L.) and tomato (Lycopersicon esculentum Mill.). There were six mulch treatments, namely grass, sawdust, baggasse, palm fruit fibre, chopped palm bunch, corn cob and a no-mulch control arranged in a randomized complete block design with four replications in the pepper trial. Corn cob was not included in the tomato trial which was also replicated four times. Mulching promoted early flowering in both pepper and tomato probably through its reduction of soil surface temperature. Fresh weight of weeds was also significantly reduced by mulching. The degree was, however, related to type of mulch, with bagasse and chopped palm bunch as the best on account of the size and density of the aggregates and compactness of the cover. Even though mulching tended to increase population of nematodes in the soil with time, there was relatively fewer incidence of root-knots in mulched pepper and tomato than in no-mulching. With the exception of palm fruit fibre, mulching significantly increased yields of both crops with bagasse and sawdust being outstanding in this regard. Superiority of the two might derive from their capacity to soak up and conserve more moisture than the rest due to the absorbent nature of their aggregates. Analysis of the nutrient composition of the different mulching materials showed that apart from grass which contained a little more than 1 percent nitrogen, the rest were very low in nitrogen and phosphorus but high in carbon with C:N ratio of over 187:1; that would rather require application of starter fertilizer to compensate for the initial depression of nitrification.

Original scientific paper. Received 26 Jan 96; revised 13 Mar 97.

THE EFFECT OF NUMBER OF NODES PER CUTTING AND POTASSIUM FERTILIZER ON THE GROWTH, YIELD AND YIELD COMPONENTS OF SWEET POTATOES ( IPOMOEA BATATAS POIR)

Department of Crop Science, University of Ghana, Legon, Ghana (F.M.'s present address: Cocoa Research Institute of Ghana, P.O. Box 8, Akim-Tafo, Ghana)

The effects of number of nodes per cutting (3,5 and 7) and different levels of potassium fertilizer application (0, 60 and 120 kg K/ha) on the growth, yield and yield components of sweet potato (Ipomoea batatas Poir) cultivar ITS 2 were investigated on Toji series soils which fall within the coastal savanna acrisols. Many of the characters measured increased with increase in node number up to 7-nodes. The 5 and 7-node cuttings established earlier and produced higher dry matter (DM) during the first few weeks of growth than the 3-node cuttings. The 5 and 7-node cuttings also gave significantly higher tuber yields than 3-node cuttings. There was no apparent advantage of the 7-node cuttings over the 5-node cuttings in all the characters studied. Similarly, there were no significant effects due to the number of nodes per cutting on leaf area development at 6 weeks after planting till time of harvesting. Number of nodes per cutting did not have any significant effect on tuber and vine DM yield as well as tuber length to diameter ratio. Potassium fertilization did not have significant effect on any of the characters investigated although it increased tuber DM yield slightly.

Original scientific paper. Recieved 28 Dec 95; revised 21 Mar 97.

OPTIMUM PLANTING DATES FOR FOUR MATURITY GROUPS OF MAIZE VARIETIES GROWN IN THE GUINEA SAVANNA ZONE

P. Y. K. SALLAH, S. TWUMASI-AFRIYIE & C. N. KASEI (

P.Y.K.S. & S.T.-A.: Crops Research Institute, CSIR, P.O. Box 3785, Kumasi, Ghana; C.N.K.: Soil Research Institute Projects, Savanna Agricultural Research Institute, CSIR, P.O. Box 52, Tamale, Ghana)

Five maize varieties, comprising NAES EE W SR (extra-early, normal maize (NM)), Dorke SR (early, NM), Abeleehi (intermediate, NM), Obatanpa (intermediate, quality protein maize) and Okomasa (late, NM), were sown at 2-week intervals from mid-May to last week of July in 1993 and 1994 at Nyankpala in the Guinea savanna zone. The varieties were assigned to main-plots and planting dates to sub-plots in the randomized complete block with four replications per year. Effects due to variety and planting date were highly significant (P< 0.01) for grain yield. The variety W planting date interaction was not significant for yield. Grain yields averaged over planting dates were 3890, 5252, 5798, 5830, and 5883 kg/ha for the varieties NAES EE W SR, Dorke SR, Abeleehi, Obatanpa and Okomasa, respectively. Grain yields for the six sowing dates averaged over varieties were 5919, 5900, 6232, 4895, 4537 and 4502 kg/ha. Grain yields for the first three planting dates did not differ significantly from each other. Similar results were obtained for the last three planting dates. Yields on the average were 30 per cent higher for the first three planting dates than for the last three. Plant dry matter yield, number of ears per plant and thousand grain weight were the parameters which showed significant positive correlations with grain yield among planting dates. The data showed that (1) for all maturity groups, maize sown from mid-May to mid-June significantly out-yielded the later plantings, (2) the extra-early and early maize varieties were lower yielding than the later varieties, and (3) there was no yield advantage in the late varieties over the intermediate types in the Guinea savanna zone.

Original scientific paper. Received 20 Aug 96; revised 11 Apr 97.

AN EVALUATION OF SOME SYSTEMIC FUNGICIDES FOR THE CONTROL OF SEPTORIA LEAF SPOT OF TOMATO

Department of Crop Science, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana

Three systemic fungicides viz. Thiophanate Methyl (Topsin M 70WP), Benomyl (Benlate 50WP) and Carbendazim (Bavistin 50WP) and a protectant, Mancozeb (Dithane M-45), were tested at Akomadan in Ghana for their efficacies and cost effectiveness against Septoria lycopersici Speg., which causes Septoria leaf spot of tomato. The optimal spray schedule for themost cost effective and most readily-available fungicide was also studied. In the dry season, when leaf spot was generally absent, no differences in efficacies of the fungicides could be detected. In the wet season, Septoria leaf spot severity was high and the three systemic fungicides were generally superior to the protectant, Dithane M-45. Among the systemics, Benlate and Topsin M performed similarly and were generally more efficacious than Bavistin. The cost effectiveness of the systemic fungicides in the wet season (indicated by benefit:cost indices (BCI) was highest for Topsin M (0.22-0.32 per cent) followed by Bavistin (0.11-0.23 per cent) and lowest for Benlate (0.07-0.13 per cent). Use of Topsin M (413 g a.i. /ha) at 1, 2 and 3-weekly applications, commencing 5 weeks after transplanting and terminating in the 9th week, resulted in area under disease progress curve (AUDPC) values of 26.83, 29.16 and 31.82 per cent wk, respectively. These values were all significantly lower (P=0.05) than the value of 38.73 per cent wk associated with the no fungicide treatment. Judicious pesticide use and possible measures for increasing tomato yields in the area are discussed.

Original scientific paper. Received 3 Sep 96; revised 26 May 97.

BROILER LITTER AS FEED FOR RUMINANTS -POTENTIAL AND LIMITATIONS UNDER NIGERIAN CONDITIONS

Department of Animal Production, University of Ilorin, Kwara State, Nigeria

In Nigeria, ruminant livestock are often underfed mostly during the dry season of the year due to high environmental temperature, poor green forage production and high cost of feed. This has resulted in the inclusion of alternative feedstuffs in animal rations. Broiler litter plays a vital role in supplying and correcting nutrient deficiencies in animal nutrition. Generally, growth rate, milk production and feed efficiency were higher in animals (sheep, goats and cattle) fed broiler litter-based diet than in animals fed control diet (without broiler litter). This paper reviews the nutritional value, health hazard, processing techniques and factors affecting the acceptability of broiler litter as feed.

Subject review article. Received 4 Sep 95; revised10 Jan 97.