The relationship between soybean (Glycine Max (L.) Merrill) seed quality and the response to molybdenum seed treatment

[摘要] ENGLISH ABSTRACT:Experi!11entsin KwaZulu-Natal showed that seed treatment with molybdenum(Mo) could double the yield and increase the protein content by 1.9% ofsoybeans grown on acidic soils. However, it was also found that soybean yield atfive of the localities was reduced on average by 8% after Mo seed treatment. Itwas surmised that the yield reductions observed after Mo seed treatment wereconnected to the quality of the seed used for planting. The aim of this project wasto assess the relationship between seed quality and Mo seed treatment and finda fast, easy quality assessment test that could be used to adapt Mo treatmentsaccording to seed quality.The first investigation entailed assessing the quality of the seed obtained, fromvarious seed lots, for planting. A number of different seed quality testingtechniques were performed and they included the accelerated ageing test,tetrazolium test, conductivity test, standard germination test and an emergence. test planted at different depths with incubation at different temperatures. All thetest results were compared with the accelerated ageing test results, to find thetest most closely correlated to the accelerated ageing test, which is regarded asthe most accurate indicator of soybean seed vigour. It was found that theemergence test where the seeds where planted at 10 cm presented a closecorrelation with the accelerated ageing test. An assessment of seed qualityrevealed that the four different seed lots provided seed of three significantlydifferent levels of quality, which could be used for further investigations.The second investigation was concerned with the reaction of the seed of differentquality levels to Mo seed treatment. Firstly, seeds from four different seed lotswere treated with five different concentrations of Mo and planted under acidicconditions. The establishment was monitored up until six weeks, at which pointthe experiment was terminated. In the second planting, seeds from the fourdifferent seed lots were treated with six different concentrations of Mo andplanted under optimum pH conditions. Emergence was monitored and afterthinning out the remaining plants were left to mature and produce seed. Theemergence percentage results from both of these two plantings did not reveal thealleged positive effect Mo seed treatment has produced in the field and nodefinite relationship between seed quality and Mo seed treatment was observed.The third investigation was concerned with the effect that osmoconditioning hadon the reaction of seed to Mo seed treatment. Seeds from two seed lots, one ofvery poor quality and the other of good quality, were pre-treated with fourdifferent levels of poly-ethylene glycol (PEG 6000) and then treated with fourconcentrations of Mo. They were planted under optimum pH conditions andestablishment was monitored. After being thinned out the remaining plants wereallowed to mature and produce seed. The emergence percentage resultsrevealed that the PEG pre-treatments greatly improved emergence percentages,especially in the poor quality seed. There were some positive effects of Mo seedtreatment observed where the lower concentrations of Mo were used, but again,no definite relationship between seed quality and Mo seed treatment was found.PEG pre-treatment appeared to help make the seeds more resistant to theharmful effects of Mo.

[发布机构] Stellenbosch University