Agriculture
Surur Khorramdel; Mahmoud Mokhtari; Hoda Latifi
Abstract
The goal of meta-analysis is to provide knowledge and better understanding of the phenomena under study. The statistical technique of a large collection of analysis results from individual studies for the purpose of integrating the findings. We conducted a global meta-analysis to evaluate the effect ...
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The goal of meta-analysis is to provide knowledge and better understanding of the phenomena under study. The statistical technique of a large collection of analysis results from individual studies for the purpose of integrating the findings. We conducted a global meta-analysis to evaluate the effect of various fertilizers on saffron yield using data obtained from peer-reviewed publication (71 studies representing 14 studies on biofertilizers, 16 studies on compost, 14 studies on humic acid, 26 studies on chemical fertilizers (NPK) and 16 studies integrated application of fertilizers). Based on the results, the highest effect size was related to the impact of humic acid on dried weight of stigma (g=3.434). After humic acid, biofertilizer, chemical fertilizer and compost were computed in the next ranks. The standard error for compost (E = 0.101) was calculated less and with higher accuracy, so it is recommended with 95% confidence interval. Based on the results of Begg and Mazumdar correlation, all studies except humic acid on dried weight of stigma, humic acid on fresh weight of stigma, manure on flower number, chemical fertilizers on dried weight of stigma and chemical fertilizers on fresh weight of flower were homogeneous. Among the application of manure rate, 60 t cow manure per ha and 5 t poultry manure per ha had the highest and lowest effects, respectively. The results of meta-analysis for compost rates on dried weight of stigma indicated that 60 t per ha had the maximum impact. The highest effect of humic acid on dried weight of stigma was computed for 30 kg/ha. Based on the results it seems that there is no good long-term plan to resolve existing problems of soil fertilizers on saffron production systems and most of the experiments are based on researcher’s opinion, ease of implementation or following published articles in credible journals. Generally, the meta-analysis results provide a basis for conducting trade-off analyses to support the fertilizer management and development strategies based on available scientific findings.
Other subject about saffron
mohamad mokhtari; Alireza Koocheki; Mehdi Nassiri Mahallati
Abstract
Studies that investigated the impact of organic fertilizers (manure, compost and biological fertilizers) and agronomical practices (density, method, date and depth of planting) on saffron yield have a long history in Iran. Due to the distribution and inconsistency in the results obtained from different ...
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Studies that investigated the impact of organic fertilizers (manure, compost and biological fertilizers) and agronomical practices (density, method, date and depth of planting) on saffron yield have a long history in Iran. Due to the distribution and inconsistency in the results obtained from different studies, a meta-analytic approach was used in the current study. for this aim, 47 organic fertilizers studies and 44 agronomical practices studies were selected from 202 gathered studies and analyzed. The criteria for the selection of studies were the adequacy of data for the present meta-analysis. Among the individual fertilizer studies, manure fertilizer had the highest impact on saffron dry weight (g= 1.493) at 95% confidence interval. Average amount, 40 to 50ton/ha of cow manure, 20 to 30ton/ha of compost that is used as a combination with Biofertilizer (Nitroxin with Nitrogen-fixing bacteria) were more effective than higher amounts of these fertilizers will be alone. Among the agronomical practices studies, plant density had the highest and depth of planting had the lowest effect size on economical yield and number of flower. The optimal density for maximum yield was 50-100 corm per (m2), optimal consumed weight average 9-12 ton per hectare observed, optimal weight of any corm was 10-20 (g). Among planting methods, row-mass method was the best optimal (inter-planting was 20 cm and intra-planting 10 cm). The best planting dates was the end of May and the first decade of Jun. Optimal planting depth was 15-20cm. Homogeneity between organic fertilizers studies was accepted and the homogeneity between agronomical practices except depth of planting studies was accepted. This heterogeneity was caused by factors such as age of farms and different regions that had the most impact on heterogeneity and effect size. The present meta-analysis aims to provide a better understanding of agronomical and fertilizers management and offer the best possible management for this crop.
