The parameters of grain filling and yield components in common wheat (Triticum aestivum L.) and durum wheat (Triticum turgidum L. var. durum)
Final grain dry weight, a component of yield in wheat, is dependent on the duration and the rate of grain filling. The purpose of the study was to compare the grain filling patterns between common wheat, (Triticum aestivum L.), and durum wheat, (Triticum turgidum L. var. durum), and investigate relationships among grain filling parameters, yield components and the yield itself. The most important variables in differentiating among grain filling curves were final grain dry weight (W) for common wheat genotypes and grain filling rate (R) for durum wheat genotypes; however, in all cases the sets of variables important in differentiating among grain filling curves were extended to either two or all three parameters. Furthermore, in one out of three environmental conditions and for both groups of genotypes, the most important parameter in the set was grain filling duration (T). It indicates significant impact of environmental conditions on dry matter accumulation and the mutual effect of grain filling duration and its rate on the final grain dry weight. The medium early anthesis date could be associated with further grain weight and yield improvements in wheat. Grain filling of earlier genotypes occurs in more temperate environments, which provides enough time for gradual grain fill and avoids the extremes of temperature and the stress of dry conditions.
Ameliorating Effects of Exogenously Applied Proline on Seed Composition, Seed Oil Quality and Oil Antioxidant Activity of Maize (Zea mays L.) under Drought Stress
This study was carried out to appraise whether or not the exogenous application of a potential osmoprotectant, proline, could ameliorate the adverse effects of drought stress on maize seed and seed oil composition, as well as oil antioxidant activity. Water stress reduced the kernel sugar, oil, protein and moisture contents and most of the seed macro- and micro-elements analyzed in both maize cultivars but it increased the contents of seed fiber and ash. Water stress increased the oil oleic acid content with a subsequent decrease in the amount of linoleic acid, resulting in an increased oil oleic/linoleic ratio for both maize cultivars. However, no variation was observed in oil stearic and palmitic acids content due to water stress. A considerable drought induced an increase in seed oil α-, γ-, δ- and total tocopherols and flavonoids were observed in both maize cultivars. However, oil phenolic and carotenoid content as well as 1,1-diphenyl-2-picryl-hydrazyl (DPPH) free radical scavenging activity decreased. Foliar-applied proline significantly increased the content of seed sugar, oil, protein, moisture, fiber and ash in both maize cultivars under well irrigated and water deficit conditions. Furthermore, exogenous application of proline increased the oil oleic and linoleic acid contents. The concentrations of antioxidant compounds namely phenolics, carotenoids, flavonoids and tocopherols estimated in the seed oil increased due to foliar-applied proline under water deficit conditions that was positively correlated with the enhanced oil DPPH free radical scavenging activity. Moreover, the increase in the contents of these antioxidant compounds and oil antioxidant activity due to the foliar application of proline was noted to be more pronounced under water deficit conditions.
Association of grain-filling characteristics with grain weight and senescence in wheat under warm dry conditions
Abstract Two field experiments were conducted in the 1980/81 and 1981/82 growing seasons to study the association of grain filling parameters with final kernel weight and test weight in three durum (Triticum turgidum, L.) and two bread wheat (Triticum aestivum, L.) cultivars. The time of complete senescence of foliage and maximum grain weight were also investigated. Data on grain-filling rate (GRF), grain-filling duration (GFD) and leaf senescence were obtained from successive samples. Temperatures above a daily average of 19.3°C during the grain-filling period reduced the GFD in 1980/81 by an average of 1.6 days per degree increase in temperature and resulted in about 6% reduction in grain yield compared to the 1981/82 season. The durum wheat cultivars showed higher GFRs than the bread wheat cultivars, suggesting differences in photosynthetic rates and/or lower respiration rates. The greater kernel weights found in some cultivars were associated with higher GFRs. Plant senescence was largely dependent on air temperature. Moreover, termination of grain filling and senescence of foliage occurred independently and were cultivar specific. It is suggested that under warm dry conditions, wheat cultivars with high GFRs and short GFDs could produce higher yields. They should be harvested, however, before the complete loss of green coloration in order to prevent shattering.