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Item Effects of duration of water stress at different growth stages on growth and yield of soybeans (Glycine max (L) Merrill) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agriculture in Plant Science at Massey University(Massey University, 1982) Laohasiriwong, SuwitFour soybean cultivars (viz. Evans, Geiso, Maple Arrow and S.J.4) were subjected to water stress at three different reproductive growth stages: i)entire reproductive growth stages (R1 to R7) ii) early reproductive growth stages (R1 to R4) and iii) late reproductive growth (R4 to R7). The experiment was conducted in the climate laboratory at the Plant Physiology Division D.S.I.R. Palmerston North, New Zealand, with 31°/23°c (day/night temperature) 70/90% RH (day/night relative humidity) and 14 hours photoperiod. The growth and development of the soybeans were markedly affected by water stress. Leaf area, final plant length, number of nodes and total plant dry weight from the stress treatments were reduced. Seed yield per plant from the three stress treatments were only 10.7, 49.6, and 24.1% relative to that of control treatment. The response of soybean yield depended on both the timing and the duration of stress in relation to growth stages whilst some other plant characters such as plant length and the number of nodes responded more to the timing rather than the duration of stress. Cultivars with the determinate growth type (viz. Evans and Maple Arrow) were apparently more sensitive to stress at the early phase of reproductive growth (R1 to R4) whilst the indeterminate growth type (viz. Geiso and S.J.4) were more sensitive to water stress at the later phase of reproductive growth (R4 to R7). The number of pods per plant was the most important yield component in determining yield although in Evans and the early stress treatment the average seed weight was the most important component. The rank of cultivars, from low to high sensitivity to water stress is Maple Arrow, Evans, Geiso and S.J.4. S.J.4 also reacted differently from the other three cultivars in many aspects. The drought tolerance test estimated through a measurment of electrolyte leakage from the cells was used and discussed. Two methods of genotype x environment interaction analysis (regression analysis and discriminant analysis) were used. The discriminant analysis had some advantages in the study of GE interaction e.g. it could be done with several characters at once and compared with the regression method it could be used with a much lesser number of cultivars and environments. Key words: Soybeans, water stress, growth stages, yield and yield components, drought tolerance test, GE interaction, discriminant analysis, principal component analysis.Item The growth and yield of maize (Zea mays L.) and soyabeans (Glycine max. (L) Merrill) grown as intercrops : a thesis presented in partial fulfilment of the requirement for the degree of Master of Agricultural Science in Plant Science at Massey University(Massey University, 1986) Kamarudin, YusoffThe effect of plant population maize (Zea mays L.) cultivar (Pioneer 3901) and AMT and Matara cultivars of soyabeans (Glucine max (L) Merill) grown together in an intercropping system was studied. In the experiment three rows of maize were sown at populations of 6, 8, 10 plants/m2 and three rows of soyabeans were planted between the rows of maize at either 50 or 75 plants/m2 replacing one of the three rows of maize. Plants were sampled for vegetative analysis during the growth of the crops and at final harvest. Total dry matter, grain yield and the components of yield and leaf area index were determined. Grain yield of maize increased from 794 to 1522 g/m 2 as the population of maize increased. However the yield of the maize was not affected by either the cultivar or the populations of the soyabeans grown among it. Grain yield and the component of yield of the intercropped soyabeans were not affected when population of maize in the mixture was increased. Matara produced higher yields than AMT when grown with maize and this was associated with production of more grain per plant and larger seeds. As the plant population of the soyabeans was increased the grain yield of Matara increased and up to 336.9 g/m2 was obtained, however the yield of AMT was not affected by a similar increase in plant population, possibily Matara had greater temporal difference and was more competative than AMT when grown in the mixture. Three methods were used to evaluate the yield of intercropped plots. These were the seed yield summed for both crops, Land Equivalent Ratio (LER) and a yield ratio based on maize. Although the results obtained depended on the method used all the three methods indicated intercropping could be more advantageous than growing maize and soya beans as pure stands. All the three methods indicated that the highest yield was obtained when the highest population of maize was combined with the highest population of soyabeans. Higher yields were obtained when Matara rather than AMT was grown in the intercropped plots.Item Seed quality and storage performance of wheat (Triticum aestivum.) and Soybean (Glycine max (L) Merrill) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agriculture Science in Plant Science (Seed Technology) at Massey University, Palmerston North, New Zealand(Massey University, 1996) Singkanipa, VarenyaFive seedlots of wheat (Triticum spp.)cvs. Norseman. Otane, Karamu and two unknown cultivars. and four seedlots of soybean (Glycine max (L) Merrill)cv. Davis, two seedlots of cv. CH187 and one unknown cultivar were assessed for prestorage quality by using different laboratory methods ie purity, thousand seed weight, seed moisture content, germination, accelerated ageing, conductivity and seed health. The results of this study showed quality differences between seedlots of both wheat and soybean. Using seed germination and vigour data, three lots of wheat with high quality, two seedlots of soybean with high quality and one seedlot with low quality were chosen and adjusted to two different seed moisture contents (10% and 14% in wheat .and 8% and 12% in soybean). Seed samples of both species were stored in open storage (muslin bags) or sealed storage (aluminium foil packets) at 20°c 75%RH or 30°c 50% RH for 8 months. All wheat seedlots and two soybean seedlots were also stored under open storage at 30°c 95%RH. Seed quality was assessed at intervals of 1,2,4, 6 and 8 months. The seed moisture content of both species in open storagechanged to reach equilibrium moisture content (EMC) with the prevailing relative humidity. At 30°c 95%RH moisture content of wheat and soybean seeds increased up to 18.5-20.5% and 22-23%. respectively while at the same temperature but lower RH (50%), SMC fell to 8.2-8.5% and 5.2-5.5%, respectively. Both low and high initial SMC of seed stored at 20°c 75%RH either increased or decreased to reach an EMC of 12.8-13.6% for wheat and 9.8-10.1% for soybean. Under sealed storage at different storage temperatures and relative humidities SMC did not change from initial levels. At 20°c 75%SMC the type of storage container had no significant effect on germination percentage or conductivity in wheat and soybean after 8 months. At 30°c, however, the germination percentage of wheat and soybean with high initial SMC in sealed storage and in open storage high RH declined more rapidly during storage than the other treatments. Germination percentage correlated reasonably well with conductivity, with conductivity readings increasing as vigour decreased. At 30°c 95% both open and sealed storage at high initial SMC resulted in seed showing a conductivity value increase with longer storage time, indicating seedlot deterioration. All field fungi were eliminated from seed open stored at 30°c 95% but storage fungi developed rapidly in all seedlots after two months. The main genus involved was Aspergillus spp. but Penicillium spp. were also found at low levels in soybean. However, under 30°c 50%RH and 20°c 75%RH storage conduction field ftingi levels in wheat and soybean were reduced during storage and seed was either disinfected or remained infected at only low levels after 8 months storage. The main field fungus present in wheat was Fusarium spp.. In soybean both Fusarium spp. and Alternaria spp. survived well along with low levels of Colletotrichum spp.. The implications of pre-storage seed quality, seed moisture levels and storage environment and their effects on seed deterioration rate and extent are discussed. The role of field and storage fungi in affecting loss of seed viability in storage and the possibility of exploiting the storage environment to obtain pathogen free seed for planting is also considered.Item A study of drying, threshing and storage conditions on the viability of soybean seeds with a supplementary study of the efficiency of a simple drying method developed : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Seed Technology at Massey University(Massey University, 1981) Jarasrangsichol, PuangthongThis study was designed to investigate the relevance of postharvest factors in maintaining the viability and storability of soybean seeds. In order to obtain high quality seeds for the drying and storage aspects of the experiment, the sequence of seed development and physiological maturity of the crop was investigated to ascertain maximum viable seed yield. The soybean cultivar 'V-53' was sown and plants were randomly sampled at 32 days after peak flowering, and subsequently every 5 days until the seeds reached physiological maturity. The changes in seed moisture content, fresh weight, dry weight, percent germination and maximum viable seed yield in relation to time after peak flowering were measured. The soybean crop achieved a maximum viable seed yield of 1344. 1 kg/ha 77 days after peak flowering. The development of the crop was prolonged by adverse weather conditions. After soybean seeds reached physiological maturity, the crop was harvested at a seed moisture content of 49.2% and germination of 96%. Further studies were carried out to investigate those factors that affect seed viability before and during storage. The drying effect on seed viability was made by comparing the effect of 6 different drying methods i.e. dehumidification, refrigeration, ambient air and heated air at 30°C, 40°C or 50°C. Seeds were dried to 8% moisture content in each case. Delays between harvest and the commencement of drying operations result in a decline of seed germinability, particularly in seedlot which was later used in the refrigeration drying system. Although drying method had no immediate effect on seed viability during drying, drying seed by refrigeration method was time consuming the drying rate being too slow and resulting in subsequent seed deterioration. The heated air methods were most efficient in assisting removal of moisture from the seed. Following drying, seeds were threshed from the pods by hand threshing or beating threshing methods. Seeds from different drying and threshing treatments were stored under 20°C - 40%RH or 35°C - 90%RH conditions for 16 weeks. The threshing of seed using a beating method caused a significant reduction in seed germinability when compared to the hand system used to remove seed from the pod. Drying method had no significant effect on seed storability when seeds were stored under good storage conditions i.e. 20°C - 40%RH. However, when seeds were stored under poor storage conditions i.e. 35°C - 90%RH, seeds previously dried at 40°C and 50°C using heated air showed a more severe drop in germination after only 2 weeks when compared to seeds dried by 30°C heated air. The effect of unheated air on seed storability was possibly not detected since there was wide variation in the results and the storage conditions of 35°C - 90%RH had severely affected seed viability after only 4 weeks storage. Seeds stored under 35°C - 90%RH conditions rapidly gained moisture to a relatively high level. This high moisture content in seeds accelerated the rate of deterioration and favoured the growth of storage fungi which were greatly responsible for loss of viability. Although there was a reduction in the germination capacity of seed stored under 20°C - 40%RH conditions after 16 weeks, these conditions were vastly superior to storage conditions of 35°C - 90%RH. In the present study, the effect of drying method was not as important as storage conditions in maintaining seed viability. However, with proper harvesting, drying and threshing the problems of maintaining high level of seed viability could be eliminated. A separate drying experiment was carried out to evaluate the possible use of the 'Kiwi' drier and its efficiency in drying various seed crops. The 'Kiwi' drier was designed at the Seed Technology Centre and consists of a cylindrical metal drum containing 2 metal tubes filled with silica gel as a dessicant. As presently constructed the drier resulted in very slow and inefficient drying of barley, pea and Tama ryegrass seeds. However, results suggest that by redesigning certain features in the 'Kiwi' drier to improve air circulation and increase the area of close contact between the silica gel and the seeds it's seed drying efficiency could be greatly improved. In addition, the 'Kiwi' drier provides an ideal storage container for seeds in tropical climates.Item Iron binding properties of whey protein, casein, soya protein and egg albumen : a thesis presented in partial fulfilment of the requirements for the degree of Master of Technology in Food Technology at Massey University(Massey University, 1993) Manvikar, NetraIron binding properties of whey protein, casein, soya protein and egg albumen were investigated in aqueous dispersions using centrifugation and ultrafiltration techniques. Protein-iron mixtures were centrifuged at 10,800 g for 20 min and iron that co-sedimented with protein was considered to be bound to the insoluble protein fraction. The supernatants were ultrafiltered to obtain iron bound to the soluble protein fraction. Both the soluble and insoluble fractions of each protein were shown to bind substantial quantities of iron from ferrous sulphate. The amount of iron bound/g to the insoluble fraction of the protein was highest for casein (87 mg) followed by albumen (80 mg), soya protein (66 mg) and whey protein (63 mg). A similar trend was observed for the soluble fraction; casein bound 74 mg iron/g protein followed by albumen (68 mg), soya protein (54 mg) and whey protein (12 mg). This binding was markedly influenced by pH of the protein-iron mixtures in the range 2 – 7. The binding data was analyzed using the Scatchard equation to obtain binding constants (k) and the number of binding sites (n). The n values obtained were ~ 2 (whey protein), 13 (casein), 200 (soya protein) and 42 (albumen). The values obtained for the binding constants were ~ 11 (whey protein), 5 (casein), 3 (soya protein) and 1 (albumen). Thus soys protein had the highest number of binding sites and whey protein had the greatest affinity for iron. Solubility of each protein was dependent on pH and it generally decreased with increase in iron concentration. The effects of chelating agents (citric acid and ascorbic acid) on the iron binding properties of the four proteins were also examined. Addition of citric acid and ascorbic acid increased the solubilities of both protein and iron. The solubilizing effect of these two acids was dependent on the protein source, pH and acid concentration. Iron binding by both the insoluble and soluble fractions decreased in the presence of citric acid and ascorbic acid, with no significant differences between the effects of the two acids. The effects of proteins and protein digestion products on in vitro iron availability were studied. Ferrous iron complexes with protein were prepared and subjected to simulated gastrointestinal digestion followed by measurement of soluble iron. The in vitro availability of iron was in the order of 26% (soya protein), 16% (casein), 14% (albumen) and 10% (whey protein). When citric acid and ascorbic acid were added prior to enzymatic digestion the availability of iron increased to 63% (soya protein), 36% (albumen), 31% (casein) and 22% (whey protein).Item A study of nitrogen fixation, nitrogen distribution and seed yield of selected legumes with two different growth types : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy at Massey University, Palmerston North, New Zealand(Massey University, 1986) Laohasiriwong, SuwitPlant growth types of the determinate and indeterminate growth forms are commonly distinguished in many legume species. However, there do not appear to be many studies where direct comparisons have been made of the two growth types in relation to nitrogen fixation and nitrogen distribution. Furthermore, there are disagreements in the literature about the yield advantage of these two growth types. This study was initiated to identify the influence of different growth types of selected grain legumes on seed yield, nitrogen fixation, and nitrogen distribution. In addition, the emphasis was also put on finding amongst the measured parameters, one that had the greatest influence on the differences observed. Initially determinate and indeterminate growth types of bean (Phaseolus vulgaris) and soybean (Glycinemax), were studied in glasshouse conditions. The indeterminate cultivar of both species had higher leaf area and nodule dry weight, more root growth, accumulated more total dry weight and had higher yield than that of the determinate cultivar. In both species, the indeterminate cultivar accumulated more total plant nitrogen than the determinate cultivar. However, only the indeterminate soybean cultivar showed significantly more nitrogen fixation (Acetylene reduction) than that of the determinate cultivar. Subsequently the same soybean cultivars ('Matara' =determinate and 'Amsoy' =indeterminate) were studied in controlled environment conditions. The indeterminate cultivar produced higher vegetative dry-matter and seed yield than that of the determinate cultivar. The higher acetylene reduction activity of the indeterminate cultivar came primarily from a greater nodule mass. About 30-40% of seed nitrogen of both cultivar came from redistribution from vegetative parts, but the stem of the indeterminate cultivar re-distributed a higher proportion of nitrogen to the seed than that of the determinate cultivar. Among several plant characters measured (viz. the dry-weights of the roots, nodules, stems, leaves, and pods, the leaf area, acetylene reduction activity and the total plant nitrogen) leaf area was identified as the key factor in determining the difference between the two growth types. In order to determine the relative importance of leaf area as a factor influencing seed yield, nitrogen fixation and nitrogen distribution the leaf area of the indeterminate cultivar 'Amsoy' was manipulated by imposing different levels of partial leaf removal starting at the flowering stage. For one treatment, partial pod removal was also applied to induce a reduced demand of assimilate. Partial defoliation of the indeterminate cultivar reduced markedly the root growth and the number of branches, but nodule growth, acetylene reduction activity and nitrogen distribution was reduced to a lesser extent. Partial pod removal did not change the overall pattern of response. When about 6 0 % o f the leaves o f t he indeterminate cultivar were removed, seed yield was reduced by about 1 7 % and it was still significantly higher than the undefoliated determinate cultivar . There was no significant difference between the rates o f nitrogen accumulation in the pods under each treatment . The final seed nitrogen concentration was not affected by defoliation treatments nor was the partitioning of nitrogen to seed. I t was concluded that there were differences between the two growth types o f soybean for seed yield, nitrogen fixation, and nitrogen distribution. Leaf area was the most important parameter in determining these difference [sic]. The greater overlapping of vegetative and reproductive growth in the indeterminate cultivar seemed to be advantageous rather than disadvantageous. This longer period of vegetative growth enabled the indeterminate cultivar to produce a bigger source capacity which consequently supported more nitrogen fixation activity and produced higher seed yield. The possible implications to tropical agriculture were discussed and some future research topic s were also suggested .Item Some effects of water stress and environment on soybean plants : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Botany at Massey University(Massey University, 1970) Beardsell, Michael FletcherAlthough a great deal of research has been carried out on the effects of water stress on plant processes, the influence of environmental conditions on plant response to water stress has received comparatively little attention. In this study the rates of CO2 exchange and transpiration and the leaf water status of whole soybean plants (Glycine max (L.) Merr. cv. Merit) were measured under contrasting sets of environmental conditions when (a) the plants were maintained under conditions of adequate soil water supply. (b) water stress was imposed by withholding water and, (c) when water stress was imposed and then relieved by rewatering. Light intensity and quality, atmospheric CO2 concentration, wind speed and daylength were all constant; the between-treatment variables were air temperature and vapour pressure deficit (VPD). Plants were grown under one of four environmental treatments in a growth cabinet and the experiments carried out under very similar conditions in a plant chamber with facilities for measuring CO2 exchange and transpiration. Details of this equipment are given. Under conditions of adequate soil water supply rates of photosynthesis were lower under low VPD than under high VPD conditions at the same temperature. The effect was particularly marked at low temperature (22.5°C). Between-treatment differences in photosynthetic rate appeared to be mainly attributable to differences in the magnitude of the mesophyll resistance to CO2 transfer. Transpiration rates were largely determined by the VPD, plants under high VPD treatments having the higher rates. At low VPD temperature had little effect on the rate of transpiration, but at high VPD plants under low temperature had lower rates of transpiration than plants under high temperature (27.5°C). Possible mechanisms whereby low temperatures may reduce transpiration under conditions of high VPD are discussed. When water stress was imposed the rates of photosynthesis and transpiration declined in parallel under all treatments at soil moisture tensions in excess of 0.2 atm. This suggested that both plant processes were subject to a common controlling mechanism, probably stomatal diffusion resistance. At soil moisture tensions below 0.2 atm. the rates of photosynthesis and transpiration were independent of the soil moisture status. Between 0.2 and 0.4 atm. tension they appeared to be determined by plant, soil and atmospheric factors. The relative rates of photosynthesis and transpiration were reduced to a greater extent at any tension between 0.2 and 0.4 atm. under high VPD than under low VPD conditions. Above 0.4 atm. soil moisture tension the rates of photosynthesis and transpiration became independent of the atmospheric conditions and it is suggested that transpiration was limited chiefly by the rate of movement of water into the root zone from the surrounding soil. Photosynthesis may have been limited by direct effects of dehydration on the biochemical components of the process at these severe stress levels. It was thus possible to distinguish three stages in the development of water stress, the significance and possible general application of which are discussed. Under high temperature/high VPD conditions the rates of photosynthesis and transpiration recovered simultaneously and to a very similar extent when stress was relieved by rewatering, the degree of recovery being inversely proportional to the soil moisture tension at the time of rewatering. Possible causes of the failure of the rates of photosynthesis and transpiration to recover to their original prestressed values are discussed. These results are discussed in relation to the findings of other workers, and suggestions for further research in this field made.