The critical period of weed interference in one variety of chickpea was determined in field experiments carried out at two sites, Tabriz 2002 and Kermanshah 2003, Iran. Chickpea culture was either kept free of weeds for 0, 12, 24, 36, 48 and 60 days after crop emergence (DAE) or weeds were allowed to grow for 0, 12, 24, 36, 48 and 60 DAE. In these experiments, chickpea yield increased with increasing duration of weed-free period and was reduced by increasing duration of weed-infested period. Unweeded conditions for the entire growing season caused 66.4% and 48.3% seed yield reduction when compared with the treatment that was weed-free throughout the growing season, at Tabriz 2002 and Kermanshah 2003, respectively. The results indicated that chickpea must be kept weed-free between the five-leaf and full flowering stages (24-48 DAE) and from the four-leaf to beginning of flowering stages (17-49 DAE) at the two sites, respectively, in order to prevent >10% seed yield loss. At both sites, reduction in seed yield, because of the increased weed interference period, was accompanied by simultaneous reduction in plant dry weight, number of branches, pods per plant and 100-seed weight. This was supported by significant and positive correlations between these traits and chickpea seed yield. There was no significant correlation between the number of seeds per pod and seed yield. A linear regression model was used to describe the relationship between weed dry weight and seed yield loss.
Okra hardseedness results in slow and uneven germination. This study determined the effects of fertilizer application and drying methods on hardseedness breakdown of okra (Abelmoschus esculentus L.) cultivars (cv. Boyiatiou', 'Veloudo', 'Clemson' and 'Pylias'). Three fertilizer level (150, 300 and 450 mg L -1 N) and two different drying methods (seeds and pods) were applied. The results showed that by increasing N application from 150 to 450 mg L -1 N increased seed germination regardless of drying method, whereas the application of 450 mg L -1 N resulted in the higher seed germination percentage, regardless of cultivar and drying method. In addition, harvesting seeds at 40 days after flowering (DAF) resulted in an increase of germination rate, especially when 450 mg L -1 N were applied. Seed germination of seeds harvested at 40 to 50 days after flowering (DAF) was reduced, especially when seed drying instead of pod drying was applied. However, for cv. 'Boyiatiou' the application of 150 mg L -1 N resulted in higher percentage of hard seeds and lower seed germination rate, whereas pod drying reduced the occurrence of hardseedness. For all cultivars, seeds from the middle part of the plant had a higher seed germination percentage at 450 mg L -1 N level, regardless of drying methods. In conclusion, increasing the N application rate up to 450 mg L -1 , harvesting seeds at 40 DAF and collecting seeds from the middle part of the plant could be a useful means for reducing the occurrence of hardseedness and increasing germination percentage of okra seeds.
Four okra cultivars (Abelmoschus esculentus [L.] Moench) were cultivated for two growing periods at nitrogen (N) application rates of 150, 300 and 450 mg N L 1 . There was no effect of N on pod size (length and diameter) or on the number of seeds per pod and seed size (mean 1000 seed weight), all these characteristics of which related to the genotype. High N application (450 mg N L 1 ), increased the seed yield of the cultivar with the lowest flower induction (Boyiatiou), but only in experiment 2. In Veloudo, seed yield was highest at 300 mg N L 1 , whereas in Pylaias and Clemson 450 mg N L 1 reduced seed yield. In all cultivars, seeds produced at an N Downloaded by [University of Missouri-Columbia] at 11:26 20 June 2016 ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT 2 rate of 450 mg N L 1 exhibited a significantly higher percent germination N, possibly by reducing the incidence of seed hardness.
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