Department of Crop Science and Horticulture

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Coffee in the economy of Tanzania and the implications of membership In the international coffee agreement
(1979) Msuya, M. Michael
We seek in this work to develop recommendations for policies that will enable Tanzania to enhance her gains from trade in coffee, in of the changing environment O’- orally. in the world coffee and economic scene We start in the first chapter with an introduction to the O/j^anian economy and identification of the place of coffee in this - z/r-omy. In the second chapter we review literature relating to the structure of the international coffee market, the commodity problem and justification for international market intervention in the form of the International Coffee Agreement (ICA). The third chapter is an attempt to assess, empirically, the effectiveness of the ICA on Tanzania’s gains, defined in terms of the agreement’s objectives as increased stability and progressively increasing trend in the real value and purchasing power of income derived from trade in coffee. We devote chapter four to a review of Tanzania’s fortunes in the ICA and the trends in world coffee production and consumption. Finally, in chapter five we review ongoing coffee programs and practices in Tanzania and develop the said policy recommendations based on the country’s experience as well as the current and expected market environ ment . Two sets of factors determine the extent to which Tanzania gains from its involvement in the world trade in coffee. First is the group of factors which, for purposes of the present study, we term endogenous factors. Within this group fall such factors as production policies, quality controls and management efficiency, all 1.2. of which factors are largely a function of voluntary actions of agents within the country’s economy. These factors could be government, industry, or grower-determined or - effected. The distinguishing trait is that they are to a large degree within the willful control of agents within the country’s economy. Distinct from this category of tors is the second set of factors, which we refer to as exogenous factors. In this category we include all factors, geographically domestic jr foreign to Tanzania, that are largely beyond the willful control of agents within the country’s economy. Under this category fall such factors as market prices, export quotas, changes in consumer demand and adverse weather conditions (be they domestic or foreign to the country). This second set of factors is further sub-divided into: (a) Exogenous factors that originate from man-made decisions and as such are subject to negotiations within the ICA or other multi lateral or bilateral framework, as would, for example, be the case with coffee export quotas within the ICA, and preferential market arrange ments between the European Economic Community (EEC) and the associated African countries, of which Tanzania is one. (b) Exogenous factors that originate from man-made decisions but whose occurrence is not negotiable. In this category are included such factors as changes in consumer demand, long-term changes in world production patterns, and technological advances affecting either or both production and consumption. (c) Phenomenal occurrences that may have their origins in man-3- made decisions or natural circumstances. Examples of these occurrences include extreme weather conditions such as serious frosts in Brazil, extreme monetary instability such as occurred at the beginning of this decide, and labor strikes affecting a major aspect of the world coffee - omy such as an extended longshoreman strike in major United SlsgU-.es coffee ports of entry. Before we start the intended discussion and analyses of the factors of concern in the present study, it is in order to outline some aspects of the historical and structural background to the Tanzanian economy and the way in which coffee and the commodity’s world trade fit into this economic framework. That is the subject of the first chapter.
Structural change in the U.S. soybean and soybean products markets: a systematic varying coefficient simultaneous system approach
(University of Illinois, 1985) Rugambisa, Jeremiah Boniface Ishengoma
The soybean industry is an interesting area for investiga- It is extremely complex and has been changing rather t ion. dramatically over the last 10 to 15 years. There exists a high degree of interaction among the markets for soybeans, oil and soybean meal. soybean Recent shocks and changes in the world economic environment have impacted substantially on the industry altering the demand for its products and even changing the participants and their roles in the marketplace.
Etiology and control of stem rot of sunflower (helianthus animus l.)
(Sokoine University Of Agriculture, 1988) Bujulu, Joel
Surveys were curried out on the distribution in Tanzania of a new sunflower disease first observed in Morogoro Region. Experiments were conducted at the Tropical Pesticides Research Institute (T.P.R.I.) ana Sokoine University of Agriculture (SUA) to identify the causal agents, assess their pathogenicity to sunflower varieties commonly grown in Tanzania and other crops normally grown in association with sunt lower, and to determine biological activity of some selected fungicides to the disease causing organisms. Out of all eight surveyed regions, sunflower stem rot was confirmed only in Morogoro region. Fusarium moni liforme She Id and F. graminearum Schwabe were identified as the causal organisms inciting the new sunflower disease which was later named "sunflower stem rot". Sunflower- varieties namely Record, Jupiter, Gor 104 and Dwarf comet were found less affected by both Fusarium spp. while Giant 549, IS 894, IS 894 amd 6F5 were more susceptible. Groundnuts, simsim. cowpeas and greengram did not show symptoms upon artificial inoculations with the two Fusarium spp. while maize, sorghum, beans and garden peas showed necrotic symptoms in the areas inoculated. The fungicides Sisthane (fenapanil) and Ridomil (metalaxyl) were not effective against both fungi in laboratory culture tests while Benlate (benomyl) was effective. But Benlate proved inffective in controlling the disease in the field during field tests.iv Severity of sunflower stem rot was more apparent in fields planted a t ve ry close spacing whether it was a monoculture or interplanted with other crops resulting in more plant deaths. It is recommended that sunflower varieties which were found resistant be distributed to peasants in Morogoro Region and that only resistant ij Ten r. .1 be used in crops like groundnuts, simsim, cowpeas intercrop u- f lower and all other Wherever stem rot is endt intercrops should be planted at w’^nr tpacin which favour disease development. . *“het particularly on breeding for more ■e •’void overcrowding ”C se.i <_«> is being suggested t« nt van The suitability of fungicide «_or.- : -I cf .> s. in peasant grown sunflower appears remote an<" .‘:urrLe«r ;.r /e i.^vxuns on this aspect sl.nould be on large farms
Reproductive efficiency traits and viability of calves of Mpwapwa cattle and their crosses
(Sokoine University of Agriculture, 1988) Das, Shoshinder Sachindra Manmohan
Fifteen years data on reproductive traits and viability of calves were analysed. Data were collected from cattle records at Livestock Production Research Institute, Mpwapwa, in Central Tanzania. The reproductive traits studied were age at first calving, calving interval (CI), dry period (DP), days open and conception rate (CR)., The genetic groups in the study were Mpwapwa, F^-crossline and Backcross having 8.0%, 54.0% and 31.0% Bos taurus genetic propor- tion, respectively. The objectives of the study were to evaluate the influence of genetic and environmental factors on reproductive traits and viability of calves, to estimate repeatabilities for reproductive efficiency traits (CI, DP and days open) and to .evaluate the relationship between reproductive traits and milk production traits. Overall mean age
The incidence, economic importance and control of aphelenchoides Besseyi Christie 1942 on rice
(Sokoine University of Agriculture, 1989) Gata, Ntombana R.
The distribution, control Aphelenchoides besseyi Christie and 1942 economic on rice importance sativa L) (Oryza cultivars grown in mainland Tanzania was studied. Survey results showed that A. besseyi was widely distributed in stored rice seeds. Hot water treatment (HWT) of dry rice seeds at 54 - 62°C for In dry seed 15 min effectively controlled seed-borne A. besseyi treatment, exposure period rather than treatment temperature was the significant factor for the control of seed-borne A. besseyi. Tested seeds of rice cultivars tolerated dry seed treatment upto 60 0 C' for 20 min in respect of viability, vigour and seedling normality. Seed treatment at 54°C controlled A. besseyi for but also 15 min following affected. The sensitivity presoaked rice seeds to HWT was genetically related following presoaking percentage germination delayed onset, vigour viability, seedling normality of some rice cultivars and of Seeds treated maximum peak, presoaking and actual Although HWT of presoaked seeds at 56°C for 15 min completely controlled A. besseyi, it also killed most seeds. However, HWT of presoaked or unsoaked seeds at 48°C for 20 min did not affect seed germination and emergence. Significant control of seed-borne A. besseyi by HWT following presoaking resulted in 10 - 27% yield increases and, larger and/or better quality grains. Booting stage of rice was the critical stage for control of A. besseyi for improvement of yield. The fifth day after the first sign of booting was identified as the most infection with A. besseyi to adversely critical affect yield stage for attributes.iii Control of A. besseyi with carbofuran applied at planting and at 50% booting stage improved rice yield but HWT of A. besseyi-infested rice seed gave better nematode control and better grain yield. Dry seed treatment to control seed-borne found to be the most appropriate method because it environment is effective, cheap and safe for to A besseyi Tanzanian the was farmers; seed and the environment
Plant structure in relation to ease of physical breakdown in the mouth and rumen
(University of Wales, 1993-09) Mtengeti, Ephraim Joseph
Grassland species were grown in the field and glasshouse and research was carried out for two years to investigate plant vascular structure in relation to physical breakdown in the mouth and rumen. Plant part morphology, vascular structural proportion and arrangement, fresh plant diet eating rate by sheep and particle breakdown characteristics were recorded. Anatomical differences, especially vascular tissue arrangement, appeared to be a major cause of the differences in intake rate between legumes and grasses. Four legumes did not differ significantly in terms of intake rate but differed significantly in terms of the proportion of vascular tissues, neutral detergent fibre content and digestibility. Tropical grasses had a higher proportion of vascular tissues, higher neutral detergent fibre content, lower digestibility, lower intake rate and were chewed into smaller particles than temperate grasses. Legumes were eaten faster and had larger particles after chewing than grasses. Legume and grass particles had a similar number of perforations or ruptures per particle. Legume leaf petiole and stem particles were longer than leaflet particles and increased the overall mean particle length of the chewed material. Petioles and stems are, therefore, important in legume particle size reduction in the mouth and rumen. Regardless of grass species, the veins of the leaf sheaths were more widely spaced than those in leaf blades, but the two plant parts were chewed to a similar particle size. Despite having a high proportion of stem and neutral detergent fibre, lucerne and spurrey were eaten quickly, showing the advantage, in respect of intake rate, of having thin pliable and/or fragile stems. The results of the present project indicate that the physical structure of plants, especially the arrangement of the vascular tissue, and plant morphology have great influence on the physical breakdown of the plants in the mouth and rumen.
Cassava processing and dietary cyanide exposure in Tanzania
(Uppsala University, 1995) Mlingi, Nicholas L. V.
Mlingi, N.L.V. 1995. Cassava Processing and Dietary Cyanide Exposure in Tanzania. Acta Universitatis Upsaliensis, Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine 571.69 pp. Uppsala. ISBN 91-554-3603-X. The relationship between dietary cyanide (CN) exposure from the cyanogenic glucoside linamarin in cassava and the methods used to process this impor tant root crop were studied in Tanzania. An outbreak of acute intoxications in southern Tanzania coincided with a drought in 1988. The affected population attributed intoxications to short-cuts made in the sun-drying of cassava roots. Processing experiments showed that these short-cuts yielded flour with high residual levels of cyanohydrin, a linamarin metabolite that is transformed to CN in the gut. A causal role of CN in the intoxications was supported by hundred-fold higher mean urinary levels of the main metabolite thiocyanate (SCN) in affected (1120 pmol/1) compared to non-aftected (7 pmol/1) population groups. An epidemic of the paralytic disease konzo, that has been attributed to CN exposure from cassava, occurred during a drought in northern Tanzania in 1985. Qualitative and quantitative interviews revealed that the estab lished way of heap-fermenting crushed cassava roots was shortened during the drought due to food shortage and intensive trade. Experiments showed that this chain of events resulted in high levels of cyanohydrin in flour. Low protein intake may have enhanced CN toxicity due to low supply of sulphur for CN to SCN conversion. Studies of 217 women from an iodine deficient area in western Tanzania showed that the total goitre rate of 73 % could be explained by iodine deficien cy as verified by a median urinary iodine of 3.6 pg/dl. Although 98% ate cassava roots daily their mean urinary SCN was only 128 pmol/1. Use of mechanical milling was associated with low SCN, probably because milling ensures complete drying of roots, which removes cyanohydrin. A mean urinary SCN of 36 pmol/1 indicated low CN exposure in 193 schoolchildren studied in Dar es Salaam. They consumed cassava roots without prior processing that effectively removes cyanogens. The low CN exposure can be explained by the use of non-bitter varieties with low linamarin levels and low consumption frequency and that ingested linamarin is partly excreted in the urine without releasing cyanide in the body.
Etude de la ramification de deux cultivars d’Ananas (Ananas comosus (L.) MERR.); “Cayenne lisse” et “Queen victoria”, en relation avec leur developpement sous diverses conditions climatiques de Pile de la Reunion.
(University Henri Poincar6, 1996) Maerere, Amon Petro
Quantifying the effects of temperature and photoperiod on phenological development to flowering in rice.
(Michigan State University, 1996-05-22) Yin, Xinyou
Accurate prediction of crop phenology is important not only for modelling purposes but alsofor crop improvement and management actions The objective of this study was to develop a Methods for predicting phonological development to flowering in rice (Oryza saliva L). from the literature were analysed to evaluate a basic equation for crop development. Beta function, commonly used as a skewed probability density function in statistics, was used if' accurately describe responses of rice development rate to both temperature and Controlled-environmcnt experiments were then conducted for detailed understanding of the physiological basis of photothermal responses of preflowering development in rice Effects of day and night temperature on development to flowering were found to be different The plants did not respond to photoperiod throughout the entire preflowering period, instead, the photoperiod-sensitive phase was sandwiched by two photoperiod-insensitive phases. It appeared that responses to both day and night temperature were stronger during the photoperiod-sensitive phase than during the two photoperiod-insensitive phases The results also indicated that leaf appearance occurring simultaneously during the preflowering development had a different thermal response from that of the development perse. Based on the experimental results, a detailed model for photothermal responses of flowering in rice was developed, using the Beta function The model, referred to as the three-stage Beta (3s-Bcta) model, describes different photothcrmal responses during the photoperiod-sensitive phase and the photoperiod-insensitive phases of preflowering ontogeny. Using parameter values derived from controlled-environmcnt experiments, the 3 s-Bet a model adequately predicted rice flowering dates observed in field conditions. It performed better than several existing models over a wide range of environments. In order to assist new plant type design, the 3s-Beta model was applied to determine optimal preflowering phenological traits of rice for an increased yield potential in three different irrigated environments in Asia. The results of this thesis were discussed in view of the experimental findings, the methodology of phenology modelling and model applications
The effect of mulching and staking on the development of early and late blights of tomato
(Tanzania Journal of Agricultural Sciences, 1998) Lyimo, H. F. I; Tiluhongelwa, T. D.; Maerere, A. P.; Njau, P.
The effect of mUlching and staking on the development of early and late leaf blight of tomato (Lycopersicon esculentum (Mill))· caused by Alternaria solani (Ell. & Md.rt.) and Phythophthora injestans (Mont.), respectively, were studied using a randomized complete block design replicatedfour times. Mulching and staking significantly (P = 0.05) reduced the incidence of early and late blights by 5 to 20% and increased fruit yield more t~an two folds compared to unmUlched and unstaked controls. The apparent rate of infection of the two pathogens was also significantly lower (P = 0.05) in mulched and staked tomato than in the controls. Mulching was more effective than staking in suppressing early and late blight diseases in tomato. Mulching and staking when combined significantly (P = 0.05) reduced the incidence of the two diseases' by 20% compared to when the two practices were used separately.
Evaluation of maturity characteristics and of yield components of high protein bean (Phoseolus vulgaris L.) varieties in Morogoro, Tanzania
(1998) Mduruma, Z.O.; Nchimbi-Msolla, S.; Reuberi, S.O.W.M.; Misangu, R.N.
Several Bean growing areas in Tqnzania have unreliable and marginal rains necessitating use of short maturing and high yielding varieties. Such varieties however, are not, readily available. This'study was done to evaluate varieties for maturity, yield and its components in the bean growing areas of Morogoro, Tanzania. Sixty four varieties from the Sokoine University of Agriculture (SUA) collection and from a high percentage protein population were grown at two locations, Mgeta (high altitude) and SUA (low altitude) in 8 x 8 partial lattice with 3 replicatiqns during the 1991 season. Yield levels were low, ranging between 0.2 - 0.8 tlha at Mgeta and 0.06 - 2.Otlha atSUA. Earlier varieties were superior in yield due to' a higher yield efficiency. Varieties grown in the cooler higher altitude areas matured late with consequent reduction in yield. Significant G x E interaction effects were observedfor all the variables, except number of seeds per pod. Positive genetic correlations were significant (P ~0.01) at both locations between yield and number of pods per plant, yield efficiency and podjilling period. Yield was genetically and negatively corrected with days to first flower, 50% podfill and 85 % maturity. Path coefficient showed that days to first flower had a consistent negative direct effect o!'l yield. At both locations, the negative genetic relationship between days to 50% podfill with yield was attributed to the negative indirect influence through days to first flower. Earlier flowering anq maturity, longer podfilling with high pod production and yield efficiency are recomme.nded for higher yields of beans in the study area.
Ecology, epidemiology and pathogenic variability of pseudomonas syringae pv. phaseolicola in the southern highlands of Tanzania.
(Sokoine University of Agriculture, 1998) Gondwe, Betty James
Investigations were carried out to determine races of Pseudomonas syringae pv. phaseolicola existing in the Southern Highlands of Tanzania and the relationship between motility and virulence of the pathogen. The epiphytic survival of a brown diffusible pigment producing strain (9337- uncertain race type) and a non brown diffusible pigment producing strain (9359-racc 6) of P.s.phaseolicola was also studied in bean genotypes Kablanketi and Uyole-90. On the basis of cultural, biochemical and pathogenicity tests, 260 isolates were identified as P.s.phaseolicola. Using the Biolog Microplate identification system, other isolates of fluorescent pseudomonads encountered were confirmed to be Pseudomonas fluorescens A and Pseudomonas syringae pv. syringae A. Race determination, using eight halo blight differential bean cultivars, showed that races 1,2, 3, 4. 5, 6. 7b and 8 exist in the Southern Highlands of Tanzania. In addition, 7.6% of the strains characterized were of uncertain race type, suggesting occurrence of wider pathogenic variability than could be categorized using the current set of halo blight differential cultivars. Races 3 and 6 were the most prevalent. Race 3 occurred at a high frequency in Mbeya and was predominant in Nkasi and Sumbawanga districts. About 32% of the isolates collected produced the brown diffusible pigment in vitro. Some brown pigment producing strains were found to be race 3. Race 3 strains, which cause a very strong hypersensitive reaction associated with systemic necrosis on several bean genotypes including Tendergreen and A53, exist in the region. Strains isolated from N.wighlii and Desmodium sp. and characterized as race 7b were less virulent on bean cultivars A52 and A53 than race 7b strains originating from P. vulgar is.I hirly-six germplasm accessions were tested for resistance to eight strains of P.s.pliasi'olicola. New sources of resistance to races 1. 3, 4, 5, 7b, and strains 9337 (brown diffusible pigment producing strain) and 14494 (closely related to race 9) were identified. Differences in motility between and within races of P.s.phaseolicola were also demonstrated. Results from epiphytic population studies showed that there were differences between bean genotypes Kablanketi and Uyole-90 in supporting the epiphytic populations of die brown diffusible pigment producing strain 9337 and race 6 (strain 9359) of I’.s.p/iiixeolieolii. The resulting halo blight disease severity scores were generally low but comparably higher on Kablanketi inoculated with race 6. In vitro and in vivo studies under greenhouse conditions were conducted to determine the inhibitors effect of garlic bulb extract on growth of races 3, 6 and a brown diffusible pigment producing strain 9337 (uncertain race type) of P.s.phaseolicola. Antibacterial activity was shown as clear zones of inhibition. Halo blight disease incidence and severity on bean genotypes Uyole-90. Canadian Wonder and Kablanketi were significantly reduced. Pseudomonas syringae pv. phaseolicola strains 9337 (a diffusible brown pigment producer of an uncertain race type) and 9359 (race 6) survived in immature flat green pod tissues at 18 to 25°C in the laboratory for nine months.
Paths of influence among components of yield in sorghum (Sorghum bicolor (L) Moench, cv Tegemeo) grown in the semi arid area of Dodoma Region, Tanzania
(1998) Reuben, S.O.W.; Rwehumblza, F.B.R.; Mahoo, H.F.; Hatibu, N.; Makungu, P.; Ashimogo, G.C.
Sorghum is a food security crop in tropical marginal areas. Improvement strategies for yield under such conditions are important. Genetic improvement for yield is done thr0ll:gh improvement of its components. Due to yield component compensation, this improvement strategy is made less rewarding. It is therefore important to know compe1J.satory mechanisms existing for better improvement strategies. Studies on the nature of component compensations in sorghum are limited and virtually lacking under Tanzanian conditions. A field experiment was conducted to investigate the nature of interrelationships among components of yield in sorghum at the experimental plots of Hombolo Research Station in the semi-arid zone of Dodoma Region, Tanzania. Six treatment combinations, of rain water harvesting techniques and fertilizer were laid out in a randomized comple,te block design (ReED) with four replications during the growing season of 1996/97. Number of grains was an important component which was significantly correlated (r=O. 982***) with grain yield and had a high positive direct effect (0.979) on yield. Average grain weight was not import~nt in influencing yield of sorghum. Plant biomass had a negative direct effect (-1.2997) on average grain weight but was not important in influencing number of grains. Plant height and percent light intercepted directly influenced number of grains and average grain weight negatively. The negative influence (- 0.8712) of plant height on number of grains was compensated to a low relationship (r= -0.337) mainly by its positive indirect influence (0.3780) through light interception. Improvement strategies should aim at shorter plants with more grains, of lesser canopy development and biomass in these semi arid areas.
Why agro-biodiversity conservation - who is responsible for what?
(FAO, 1999) Reuben, S. O. W. M.; Mgembe, E.
Agro-biodiversity conservation is an important ingredient with potential for food security and for medicinal purposes. In the marginal semi-arid areas of the world, there is often nutritional deficiency due to low level of edible flora diversity during most parts of the year. Availability and knowledge on the utilisation of available indigenous and traditional flora as a food source is therefore important to alleviate nutritional and health problems of people in these areas. In Tanzania for example, there are several species of indigenous plants, both herbs, shrubs and trees available in both marginal and fertile areas with high rainfall areas which are either known or unknown to the local people as nutritional and medicinal plants. An example of such plants available in Tanzania is shown in Table 1. However, the current situation indicates that loss of agrobiodiversity is on the increase. It is estimated that about 34,000 species, constituting about 12.4% of plant species are in the danger of being extinct. This results into the depletion of food to the rural and urban people and loss of plants for healing various ailments for animals, plants and humans.
Research note on the distribution and relative importance of bean bruchid species aconthoscelides obtectus (say.) and zabrotes subfosciatus (boh.) in Tanzania
(2000) Misangu, R.N.; Nchimbi-Msolla, S.; Reuben, S.O.W. M.
Two bean bruchid species Acanthoscelides·obtectus (Say.) and Zabrotes subfasciatus (Boh.) are known to destroy beans in storage. However, the distribution and relative. importance of these species have not been established in Tanzania. In this study, a bf!an bruchid survey was carried out to find out if the two bean bruchid species occurred in th~ country. The survey was corzduded In 1993 and it was observed that both bean bruchid species were present in all regions surveyed. However, the speCies A. obtectus was more dominant in all. regions except in Ruvuma and therefore' appeared to be relatively more important than Z. subfasciatus. The occurrence of the two species in all surveyed regions indicates that both species are of economic importance in the country. There was no indication that the two species occur in well defined ecological zones.
Inheritance of resistance to bacterial blight in ten rice (oryza sativa l.) cultivars
(2000) Luzi-Kihupi, A.; Khush, G.S.
Ten rice cultivars from the International Rice Germplasm Centre originating from Bangladesh were analysedfor the~r genetics of resistance to bacterial blight. The test cultivars were selected on the basis of their high level ofresistance to races IV & VI ofXanthomonas oryzae pv. oryzae. The mode ofinheritance was studied by crossing the test cultivars with Taichung Native 1 (TNI) which is highly susceptible to the races 1,2,3;4 & 6 of X. Oryzae pv. oryzae. The genetic analysis revealed that the test cultivars have two recessive genes conferring resistance to races 1 (PX 061) and 6 (PX 079) of X. oryzae pv oryzae, respectively. The allelic relationship of genes conferring resistance with xa-S and xa-13 was studied in progenies derived from crosses between the cultivars and IRBBS and IRBB13 which are near isogenic lines carrying genes xa-S and xa-13 respectively. The Chi-square analysis of F2 populations revealed that resistance ilJ these cultivars to race 1 was conferred by xa-S. Resistance to race 6 was found to be conferred by another gene which was non-allelic to xa-13.
Regulation of gynophore elongation and fructification in the peanut arachis hypogaea L.
(Uniiversity of California, 2001) Mnzava, Nameus Abel
The regulation of peanut gynophore elongation and the fructification process were studied using Spanish bunch variety grown under constant temperature (26.5°C), photoperiod (12 hr) and relative humidity (ca 90%) in a growth chamber. The experimental material consisted of tagged flowers or gynophores continuously made available by replanting. A technique utilizing the floral morphology was devised to study effects of exogenous growth substances applied independently or in combinations on the induction of IM activity (gynophore initiation) in the absence of fertilization and syngamy. Growth substances are able to evoke IM activity thus substituting for the syngamic stimulus. The effect of GA was dose-dependent suggesting that it may be a critical factor in gynophore initiation, however, a mixture of GA, IAA and BA was more effective than individual or combined effects of BA and IAA. Morphactin showed stimulatory effect on IM activity. When applied to fertilized flowers, CEPA and Ag+ ions inhibited IM activity, the latter by postponing hypantha abscission. In the absence of exogenous auxin, gynophores initiated without fertilization failed to show geotropic curvatures denoting the role of auxin in mediating normal geotropism. Growth substance initiated gynophores were incapable of fructification and their limited elongation was suggestive of the necessity of proembryonic secondary stimuli for these processes. Gibberellic acid promoted while other tested growth substances i.e. IAA, BA, CEPA, TIBA, CCC and morphactin inhibited intact gynophore elongation. Ovule removal stagnated elongation partially overcome by GA confirming the role of the proembryos for sustained IM activity. Auxin or BA inhibited GA- promoted intact gynophore elongation depending on gynophore age auxin being more inhibitory on the younger gynophores being least responsive irrespective of concentration. When applied to flowers at anthesis, morphactin transiently inhibited geotropic curvature development but copiously altered gynophore trajectory.94. The size and activity of the IM zone decreases towards the ovule base with progressive gynophore lengthening. Gibberellic acid affects elongation by increasing length of IM cells whose elongation is basipetally polarized. inverse The relationship between fructification depth and gynophore length is attributed the to decreasing size and activity together with internal differentiation of the IM zone with age. A definition of peanut 'fruit-set' is suggested as being at time of IM induction (i.e. gynophore initiation phase of fruit development) and the gynophore as a physiologically unique young fruit. The observation that ovule removal delayed but did not prevent curvature development ot excised gynophores suggested the perceptive and responsive nature of the IM to geotropic stimulus. Morphactin enhanced elongation of excised gynophores for all concentrations with optima at 0.1 and 10 ppm and effectively altered geotropic curvature even at 0.1 to I ppm. Higher morphactin concentrations relationship rendered between gynophores the ageotropic. anti-geotropic effect There and was an inverse growth stimulation. Morphactin, however, failed to stimulate growth in the presence of auxin which partially reversed its effects on geotropism. Auxin inhibited excised gynophore elongation for all concentrations but progressively reduced the degree of curvature. The effect of morphactin and auxin on elongation are further evidence on gynophore physiological similarity to roots and the regulation of geotropic curvature by auxin. Tri-iodobenzoic acid (TIBA) and BA inhibited elongation and curvature with increasing concentration, TIBA more drastically than BA. While GA stimulated growth without appreciable effects on curvature, it partially reversed concentration dependent ancymidol-induced inhibition of these parameters. The fructification process, characterized as simultaneous cessation of gynophore elongation and ovule enlargement is enhanced by growth inhibitors,95. morphactin, IAA and CEPA while GA postponed it by perpetuating IM activity with resultant greater fructification depths. The inhibitory effects of Ag+ions, an anti-ethylene agent on fructification suggest the involvement of ethylene in regulating this process. Depth perception by gynophores is attributed to endogenous hormones acting on the IM. Pericarp growth which is mainly by water retention by the tissue precedes that of the seed but the latter accumulates most of the dry weight in the course of growth. Benzyladenine (BA) enhances fruit growth by increasing water content and kernel dry matter. Distal seed growth was greatly improved by BA treatment by increasing its sink strength which resulted in the reduction of pops and single seededness.
Performance of early maturing mutants derived from 'supa' rice (Oryza sativa L.) cultivar
(2001) Luzi-Kihupi, A.; Zakayo, J.A .
Supa rice (Oryza saliva L.) cultivar which is very popular in Tanzania was sent for irradiation at the Seibersdorf Laboratory, Vienna, Austria in 1994. The dry seeds were irradiated with gamma rays using three doses (170, 210 and 240Gy) from Cobalt 60 (60CO) in order shorten the plant height and maturity period. From the resulting mutantbpopulations originating from modified single seed descent method, five very early maturing lines plus the original cultivar were evaluated in replicated trials at two sites (SUA and Dakawa) in 1999. The trial was laid in a Randomised Complete Block Design replicated three times. The data generated include plants height, days to 50% flowering, panicle length number of productive tillers per plant, 1000 grain weight, percent filled grains per panicle and grain yield. The mutants and the parent were also screened for grain quality characteristics. The data collected were subjected tp the Analysis of Variance and correlation analysis using MSTAT -C. Path coefficient analysis was also performed to determine the cause - effect relationship. The analyis of variance revealed that there were significant differences between the mutants and their parent for all the characters tested except 1000 grains weight and panicle weight. The mutants flowered up to 24 days earlier than the parent. Further analysis revealed that grain yield was positively correlated with percent filled grains per panicle. Days to 50% flowering and 1000 grain weight exerted negative direct effect on yield. Changes in grain quality were also observed emphasizing the importance of conducting cooking and taste panel tests.
Cashew management and its effect on soils and intercrops: the case of sulphur dusting in South Eastern Tanzania
(Katholieke Universiteit Leuven, 2001) Ngatunga, Edward L.
This study examines management of cashew groves in South Eastem Tanzania and the effect of adopting sulphur dusting on soils and on cashew and its intercrops. Production of cashew nuts, an important cash crop in South Eastem Tanzania, is constrained by powdery mildew disease caused by Oidium anacardii Noack To get high yields, farmers have to dust the trees with 90 kg of sulphur per hectare After a decade of sulphur use, there is widespread concern about future productivity of the soils because buffering capacity of the soils to withstand prolonged sulphur use is not known. Production of cashew nuts is also low due to planting in marginally suitable areas The other associated problem is the lack of a strategy to address soil acidity arising from sulphur use The main objective of the study is therefore to find approaches that will ensure sustainable production and management of the cashew-intercrop based farming systems in South Eastem Tanzania. To evaluate soil suitability for the cashew nut tree, henceforth called the cashew tree, soil profile features and physico-chemical properties of soils of 16 representative cashew groves on the Makonde plateau and 14 in the Inland plains were studied. Soil properties indicate that on the Makonde plateau soils arc sandy, highly weathered, deep and devoid of mottles, nodules and hardpans. Ferralsols constituted over 60 % of the soil groupings in cashew groves sampled on the plateau Several soil groupings such as Acrisols, Alisols, Phnthosols, Cambisols and Phaeozems were found in the plains where soils are generally clayey and often shallow and less weathered. Through multivariate analysis, the relationship of 19 soil parameters and 20 cashew tree parameters revealed that tree dimensions were larger and had higher yields on deep, strongly weathered soils most common on the Makonde plateaux On shallow, weakly weathered soils found in the Inland plains, trees had smaller dimensions and low yield. The fact that the plant grew favourably on the plateau, regardless of the low chemical fertility, shows that cashew trees are more sensitive to physical than to chemical limitations of the: terrain. Buffering capacity of cashew growing soils was studied by titrating soil samples from different groves with acid and relating changes in pH to soil properties. Buffering capacity was strongly and positively correlated with percent clay and weakly with percent organic carbon of the soils. Buffering capacity of soils on the Makonde plateau was comparable to that of soils in the Inland plains. Due to the low initial pH and low clay content of soils of the Makonde plateau, acidification of these soils is more likely to reach to critical levels. To verify to which extent past sulphur dusting affected the soil of farmers’ cashew groves, the pH of 70 sulphur dusted groves was compared to 70 non-dusted groves. The survey indicated that use of sulphur has lowered the pH of soils on the Makonde plateau, while soils of the Inland plains have not been affected. To predict the effects of sulphur use on annual intercrops of cashew trees, twelve 3-year field experiments in which sulphur was applied on maize, sorghum and cowpeas were conducted at three locations. Sulphur rates varied from 0 to 240 kg ha’1. Results showed that sulphur decreased germination percentage and grain yield of sorghum and maize, beginning from the second year of application of 120 kg ha'1 and above The decrease was most pronounced in soils on the Makonde plateau. Cowpeas were tolerant to sulphur use. Through an incubation experiment set out to evaluate the ability of Mikindani lime (burned coral lime), Minjingu rock phosphate and ash from cashew leaves to neutralise soil acidity, Mikindani lime was found to be the most suitable material. It raised the soil pH from 3.8 to 6.0 at the rate of 0.3 ton ha’1 costing USS 10 for procurement and application in the field. Both Minjingu rock phosphate and ash required large amounts of materials, resulting in a higher cost. This study has shown that the most important soil properties to check when planting cashew trees are soil depth and weathering status. Deliberate effort should be made to reduce quantity of sulphur used on the Makonde plateau, as the risk for adverse effects of acidification is highest here As risk for soil acidification is less pronounced in the Inland plains, sulphur use can be continued, however, periodic monitoring of soil pH is recommended. To lessen the acidifying effect of sulphur, its use can be reduced by applying crop cultural practises, such as pruning and burning of infected twigs and leaves. Organic fungicides can be an alternative to sulphur but they have the disadvantage of being more expensive and more toxic to humans and animals than sulphur. Although burned lime has proven to be effective to raise the pH of the acidified soils, further research is needed to investigate its effect on the yield of cashew trees and cashew intercrops. An integrated approach to address the mildew problem should also involve a long-term strategy to evaluate/breed for disease resistant tree types.
Variation and inter-relationship, between yield and, some agronomic characters in induced rice (Oryza sativa L.) mutants
(2001) Luzi-Kihupi, A.
A high yielding, locally adapted cultivar Salama of rice (Oryza sativa L.) which was recommended for cultivation in Tanzania since 1978 was irradiated with gamma rays using two doses (170 & 210 grays) from Cobalt 60 (60C0) in order to shorten the plant height. Twenty three mutant lines in M5 and M6 generations plus two controls were sown in a randomised complete Block Design (RCBD) and replicated three times at the Sokoine University of Agriculture (SUA) farm in Morogoro, Tanzania. The objective of the study was to estimate genetic parameters and the association of various traits with yield. The combined analysis over two years was used to estimate genetic variances heritability and expected genetic gain from selection. The data generated were also used to perform correlation and path coefficient analysis. Analysis of variance revealed significant differences, among the tested genotypes for all the characters tested. Significant genotype X Year interactions were observed for all the characters except number of tillers per plant and 1000 grain weight. High genotype coefficient of variation heritability estimates and expected genetic advance were recorded for plant height number of tillers per plant and 1000 grain weight. Correlation and path coefficient analysis revealed that days to 50% flowering and number of panicles per square metre were important characters that incluenced yield

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