Authors:P. Bónis, T. Árendás, I. Jócsák, C. Mikecz, G. Micskei, and L. Marton
Inbred maize lines were treated with normal and double rates of post-emergence herbicides in a small-plot field experiment in one dry and one wet year. The chlorophyll a + b content of symptom-free ear-leaves was determined using a spectrophotometer after 50% silking in order to determine whether various rates of post-emergence herbicides had any effect on the chlorophyll content at flowering and how this was influenced by the type of year. The chlorophyll a + b content of the inbred lines was greatly dependent on the year, with values twice as high in the wet year as in the dry year. Treatment with tembotrione + isoxadifen-ethyl had no effect on the chlorophyll content in either year. Both rates of mesotrione + terbutylazine reduced the chlorophyll a + b content of one stress-sensitive inbred line in the dry year, but not in the wet year. In the wet year bentazone + dicamba increased the chlorophyll content, but only for one line was this effect significant irrespective of the dose. In the dry year the double dose caused a significant increase in this genotype, but the chlorophyll contents of the other lines did not differ significantly from the control.
Authors:K. Bharti, N. Pandey, D. Shankhdhar, P.C. Srivastava, and S.C. Shankhdhar
A two-year field experiment was conducted to study the effect of three zinc levels 0, 20 kg ZnSO4 ha−1 and 20 kg ZnSO4 ha−1 + foliar spray of 0.5% ZnSO4 solution on plant height, leaf area, shoot biomass, photosynthetic rate and chlorophyll content in different wheat genotypes. Increasing zinc levels was found to be beneficial in improving growth and physiological aspects of genotypes. Soil application + foliar spray proved to be the best application in improving all the parameters. Zinc application brought about a maximum increment limit of 41.8% in plant height, 101.8% in leaf area, 86% in shoot biomass and 51.1% in photosynthetic rate irrespective of stages and year of study. A variation was found to occur among genotypes in showing responses towards zinc application and PBW 550 was found to be more responsive.
Authors:R. Arora, U. Joshi, P. Gupta, and J. Singh
Mothbean plants (resistant and susceptible genotypes) were inoculated with
Yellow mosaic virus
(YMV) at 30 days after sowing (DAS), under controlled conditions in a naturally lit net house. Leaves samples were collected at 31, 33, 35, 37, 48 and 66 DAS and analysed for pathogenesis related enzymes and chlorophyll content.
Yellow mosaic virus
affects the activities of enzymes related to pathogenesis in mothbean even at 24 hours after inoculation. Activities of enzymes like peroxidase, polyphenol oxidase, phenylalanine ammonia lyase and tyrosine ammonia lyase were increased, whereas catalase activity was found to decrease in the leaves of inoculated plants of all the four genotypes tested, RMO 225 and HM 61 (resistant), GMO 9703 and GMO 9704 (susceptible), as compared to the uninoculated plants. Peroxidase activity increased markedly in the susceptible genotypes as compared to the resistant genotypes of inoculated plants. The activities of polyphenol oxidase showed an increasing trend in the inoculated leaves of resistant genotypes, as compared to the resistant genotypes of uninoculated ones. The results indicate that the differences between tolerance and susceptibility of hosts are quantitative as well as qualitative so defence against a pathogen entails major changes in the biochemical components of the plant. A probable role of these enzymes for defence against YMV in mothbean is discussed.
Authors:K. Balla, S. Bencze, T. Janda, and O. Veisz
As a consequence of climate change, the incidence of extreme weather events has increased in Hungary, as elsewhere. Extremely high temperatures are the factor causing the greatest problems for agriculture and crop production. The aim was to determine the heat tolerance of two wheat varieties (Plainsman V. and Mv Magma) by measuring physiological and yield parameters under high temperature conditions (35/20°C day/night) in the phytotron. Heat stress had a substantial influence on the chlorophyll content, antioxidant enzyme activity and yield parameters of the two winter wheat varieties. Heat stress during grain filling led to a significant reduction in the yield, biomass, grain number, harvest index and thousand-kernel weight. Significant differences could be detected between the two varieties, confirming the greater heat sensitivity of Plainsman V. and the better heat tolerance of Mv Magma. The importance of the antioxidant enzyme system was demonstrated in defence against heat stress. The activity of the enzymes glutathione-Stransferase (GSH-S-Tr), ascorbate peroxidase (APx) and catalase (CAT) was enhanced in Plainsman V., and that of GSH-S-Tr and CAT in Mv Magma. The tolerance of the wheat varieties appeared to be correlated with the antioxidant level, though changes in activity were observed for different antioxidant enzymes in the two genotypes tested.
Among the abiotic stress factors influencing the growth and productivity of wheat varieties, extremely high temperatures have the most limiting effect. In an experiment set up in the gradient chamber of the Martonvásár phytotron to test the effect of various temperatures on four winter wheat varieties and one variety of spelt, substantial differences were observed in the heat stress tolerance of the varieties. There was a considerable reduction in the number of shoots and spikes as the result of heat stress, leading to a drastic loss of grain yield. It was clear from changes in the biomass and in the grain:straw ratio that extremely high temperatures led to a substantial reduction in the ratio of grain to straw in the varieties tested. In response to high temperature the wheat plants turned yellow earlier due to the rapid decomposition of the chlorophyll content. This resulted in a considerable shortening of the vegetation period and early ripening. Reductions in the parameters tested were observed at different temperature levels for each variety, indicating considerable differences in the ability of the varieties to adapt to abiotic stress factors.
The effect of the foliar fertilizer Campofort Special-Zn (CSZn) and the plant growth regulator Rastim 30 DKV (RM) on growth, yield parameters and seed protein content was studied in mung bean [
(L.) Wilczek] plants grown under greenhouse and field conditions. CSZn at a dose of 10 l per ha, and RM at doses of 3, 30 and 60 g per ha were applied alone or in combination (before flowering and 14 days after first application). The initiation of flowering and ripening processes and the chlorophyll content Chl (
) were evaluated. At harvest, total yield and yield components (number of pods per plant, seed number per pod, single pod mass, seed mass per pod), germination of seeds and seed protein content were determined. RM applied alone induced intensive flowering, increased the number of pods and yield components per plant, accelerated the ripening of the pods, increased the Chl content in the leaves and delayed senescence in treated plants. The mixture of RM with CSZn (60 g + 10 l per ha) and RM alone at a dose of 60 g per ha had a retarding and morphogenic effect on the growth of treated plants and also decreased the protein content and germination of the seeds. The best results for all studied parameters were achieved in the field at a dose of 30 g RM + 10 l CSZn and under greenhouse conditions at a dose of 3 g RM + 10 l CSZn.