Alenazi, Mekhled Mutiran (2011) Improvement of okra (Abelmoschus esculentus) growth, yield and qualtiy by using plant growth regulators in vivo and in vitro conditions / Mekhled Mutiran Alenazi. PhD thesis, University of Malaya.
Abstract
Studies were conducted to investigate the effects of plant growth regulators on okra growth, yield and quality development using different techniques of application in a commercial vegetable field in Banting, Selangor, Malaysia. The experimental design employed on the commercial field was a randomized complete block design (RCBD). The different growth hormones were applied directly, internally, to the selected parts of the okra plant. In the flower injection treatment, injection was applied on the okra flower using IAA at different concentrations. The pod set percentage, and length was maximal in the 25 mg/l IAA treatment compared to the control. Higher percentage of healthy seed per plant was also recorded using 25 mg/l IAA followed by control and 50 mg/l IAA. However, a high concentration of IAA (200 mg/l) inhibited seed production and brought about Stenospermocarpy which resulted in 100% aborted seeds. Total soluble solids (TSS) and vitamin C content in the pod markedly increased as a result of IAA application at all the different concentrations. The highest K+ content was found in 25 mg/l IAA treated plants. In addition, the iron (Fe) content increased significantly in IAA treatments at all concentrations compared to the control. The flower injection method using different NAA concentrations showed higher percentage of pod setting in the 25 mg/l NAA treatment compared to the higher NAA concentrations. Pod weight increased in 25; 50 and 100 mg/l NAA treatments compared to the control. Healthy seed percentage was maximal in 25 mg/l NAA treated flowers whereas 100 mg/l NAA treated flowers exhibited a lower percentage of healthy seeds, but a higher percentage of aborted seeds. Using different GA3 concentrations, the highest pod setting (100%) was obtained at 100 mg/l GA3. GA3 at 50, 100 and 200 mg/l produced a higher percentage of healthy seeds per pod than 25 mg/l GA3 and control. The highest TSS, vitamin C and K+ content was observed in the 100 mg/l GA3 treatment. With ovary injection, percentage of pod setting was maximal at 25 mg/l IAA and minimum at 100 mg/l IAA compared to the control. IAA at 25 and 50 mg/l concentrations increased pod diameter by 6-20% whilst 25 mg/l IAA was the best treatment for growth and pod parameters except for healthy seed production and Mg pod content. Ovary injection using different NAA concentrations produced higher pod set percentages (98.53 and 94.97%), TSS and vitamin C content at lower NAA concentrations (25 and 50 mg/l) compared to the control. Maximum healthy seed percentage per pod was recorded in the 25 mg/l of NAA treatment, while the highest aborted seed percentage was observed at 100 mg/l NAA. With regard to the application of different concentrations of GA3, highest pod setting occurred in the 25 and 50 mg/l GA3 treatment and the lowest was observed in 200 mg/l GA3 and the control. GA3 at 25 and 50 mg/l produced bigger pod size with higher pod weight than at other concentrations. Healthy seed percentage was highest at 50 mg/l GA3 and lowest at 200 mg/l GA3. In the stem injection method, IAA at 100 and 200 mg/l produced taller plants than, treatment at 25, 50 mg/l IAA and the control treatments, which meant that plants treated with 100 and 200 mg/l had the higher number of branches, leaves and pods than the other treatments. Chlorophyll content, quantum yield of chlorophyll fluorescence (Fv/Fm) and growth and pod parameters were not affected by the different concentrations of IAA. The tallest plant was obtained with the lowest concentration of NAA (25 mg/l) used compared to other treatments. It was observed that different concentrations of NAA injected into the stem did not affect growth and pod parameters. Application of 100 mg/l GA3 greatly increased plant height compared to the control. It was found that all concentrations of GA3 used increased chlorophyll content per leaf by 37, 45, 60 and 55% compared to the control. The pod number per plant, pod length, pod diameter, pod size, pod weight and percentage of healthy seeds per pod were significantly affected by the different concentrations of GA3. In the seed soaking method, the highest germination percentage and tallest stem were achieved with 25 mg/l IAA compared to the control. Chlorophyll content and the quantum yield of chlorophyll fluorescence (Fv/Fm) were higher in the 25 and 50 mg/l IAA treatments, compared to the control. Maximum healthy seed percentage was obtained with 25 mg/l IAA while the lowest was obtained in 200 mg/l IAA treatment. Likewise, 25 mg/l NAA gave the highest germination percentage (100%) compared to control (77.5%). Application 25 and 50 mg/l NAA brought about a highly significant effect on plant height compared to the control. Vitamin C and K+ were affected significantly by the different concentrations of NAA. The highest plant height was recorded in 200 mg/l GA3 (check this out?). The highest chlorophyll content and quantum yield of chlorophyll fluorescence (Fv/Fm) was found in the 200 mg/l GA3 treatment. However application of 100 and 200 mg/l GA3 improved okra growth parameters, seed production and mineral element content compared to the other treatments. In the seed soaking method with in vitro culture, the germination percentage was highest in 25 and 50 mg/l IAA treated plants compared to the control. The chlorophyll content, chlorophyll fluorescence Fv/Fm yield, number of pods and pod size per plant were higher in 50 mg/l IAA treated plants compared to the control. On the other hand, for seeds soaked using different concentrations of NAA, the highest germination percentage (100%) and plant height was obtained with 25 mg/l NAA. The tallest plants, highest number of pods and biggest pod size were obtained with seeds soaked in 200 mg/l GA3. From the results, it can be concluded that lower concentrations of auxins (25 and 50 mg/l, IAA, NAA) and a higher concentration of GA3 (100 and 200 mg/l) were the best treatments for okra growth and development. In addition to that, it can be summarized that the innovative flower and ovary injection methods improved growth, plant production and pod quality. Furthermore, the seed soaking technique (in vivo) was better than the in vitro application injection techniques. The stem injection method did not show any effect except with GA3 application.
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