CREA Journals (Consiglio per la ricerca in agricoltura e l’analisi dell’economia agraria)
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Effect of nitrogen fertilizers on radiation use efficiency, Crop growth and yield in some maize (Zea mays L) genotypes
Get PDFNitrogen is the most important element required for plant growth and development. It is a key component in many biological compounds that play a major role in photosynthetic activity and crop yield capacity. Variation in nitrogen availability can affect plant development and grain production in maize. The effect of nitrogen availability on grain yield of maize can be assessed by physiological components such as the interception and efficient use of radia¬tion and partitioning of nitrogen to reproductive organs. Nitrogen fertilization affects maize dry matter production by influencing leaf area development, leaf area maintenance and photosynthetic efficiency of the leaf area. The objective of this study was to determine the effect of high and low nitrogen levels on morpho-physiological traits, radiation use efficiency and yield behaviour in long and short duration genotypes of maize. Field experiments were conducted in two growing seasons at five nitrogen levels: recommended dose of nitrogen (RDN), RDN+25%, RDN+50%, RDN-25% and RDN-50%. Ecophysiological traits such as leaf area index (LAI), intercepted photo¬synthetically active radiation (IPAR), fraction of photosynthetically active radiation intercepted by plants (FRI) and radiation use efficiency (RUE) significantly improved with the application of 25 and 50% nitrogen higher than the recommended dose. At both high and low nitrogen level, hybrids PMH1 (long duration) and JH 3459 (short dura¬tion) showed higher efficiency for converting IPAR into dry matter. Also, hybrids were more responsive to varia¬tions in nitrogen supply than their female and male parents in various physiological traits. Correlation of different physiological traits and grain yield at recommended, high and at low nitrogen levels was positive and significant, while for phenological traits, it was negative and significant
Comparison of the performance of synthetic maize varieties created based on either genetic distance or general combining ability of the parents
Get PDFSynthetics varieties are grown by farmers and used by breeders to select new inbred lines. In countries unable to market hybrids, use of synthetics leads to yield improvements over landraces. Synthetics are derived from intercrossing inbred lines known to possess high general combining ability (GCA) as measured via crossing with testers and phenotyping for yield in multiple environments. Genetic similarity (GS) between lines measured by molecular markers may efficiently estimate GCA. Although the prediction of specific combining ability (SCA) of lines via GS has not been successful, it may have potential to predict the suitability of lines to form a synthetic variety. As this has not been reported, the objective of this research was to compare the performance of four synthetic maize varieties developed using GS calculated between parents using SSR markers with the performance of synthetics developed using GCA based on yield. Synthetics were phenotyped for yield and other agronomic traits in replicated field trials in several environments. The two synthetics formed based on low GS (0.34 and 0.33) performed better than all other synthetics in yield and most agronomic traits. The synthetics formed based on high GS (0.77 and 0.53), performed worst for nearly all traits. The GCA-based synthetics were generally intermediate for all traits. Response of synthetics to environmental variation and efficiencies gained via use of molecular markers in synthetic formation is discussed
Carotenoid and SSR marker-based diversity assessment among short duration maize (Zea mays L) genotypes
Get PDFBased on analysis of variance using a CRD model, significant variation for kernel carotenoid content was found to be present in 25 maize (Zea mays) genotypes. Total carotenoid content was found to be at a minimum (0.94 μg/g) in the white kernel line Sikkim primitive-1, whereas as much as 38.25 μg/g was observed in a dark yellow colored kernel line (1490). TLC profiling of total carotenoids showed that out of 25, 11 lines also had high provitamin-A content, in addition to high kernel carotenoids. Kernel color did not resolve any strong correlation with either total carotenoid content or provitamin-A. Thereby, selection of genotypes for high carotenoid and provitamin-A based on kernel color may not be successful. Jaccard’s similarity coefficients, based on SSR data, were found to vary from 0.17 to 0.97. The highest value of genetic similarity (0.97) was found between Pop31B and Pop31C and therefore they seem to be most similar, whereas inbred lines Pop31D and POB-3, and 1586 and Tarun-1 were most divergent (0.17). The UPGMA den¬drogram constructed using Jaccard similarity coefficients of SSR marker data divided the 25 lines into four groups (A, B, C, and D). Each broad group (Group A and B) was further divided into clusters, thus a total of seven clusters were formed. Cluster strength varied from a minimum of 1 member in cluster III of Group B to a maximum of 5 members in cluster II of Group B. Clustering patterns, in general, revealed that lines with high carotenoid content did not occupy the same cluster. A similar distribution was also observed for lines with a high provitamin-A con¬tent. The marker based clustering pattern therefore did not show strong correlation with quantitative data. Based on total carotenoids and relative provitamin-A content, 11 lines were identified to be a potential source for biofor¬tification of carotene in maize
Mycorrhizal symbiosis and bioavailability of micronutrients in maize grain
Get PDFField experiments were conducted in calcareous and non-calcareous soils in order to study the biofortification of Fe and Zn in maize grain using arbuscular mycorrhizal fungal (AMF) symbiosis. Treatments consisted of two levels of FeSO4 (12.5 and 25 kg ha-1), two levels of ZnSO4 (12.5 and 25 kg ha-1) and two mycorrhizal treatments [with (M+) or without (M-)] inoculum carrying Glomus intraradices) replicated four times in a factorial RBD. The results revealed that AMF colonization significantly increased soil available Fe (M- 1.9; M+ 2.1 mg kg-1) and Zn (M- 4.16; M+ 4.50 mg kg-1). Siderophore production in M+ plants (51.4 μmol cm-3 hr) were higher than M- plants (39.5 μmol cm-3 hr) and the increase observed irrespective of levels of Fe and Zn. Increased availability of Fe and Zn in soil in combination with enhanced concentrations in plants assisted M+ plants to maintain higher micronutrient contents in grains (Fe M- 31.2, M+ 35.3; Zn M- 45.1, M+ 52.4 mg kg-1). Mycorrhizal plants produced grains with had 10- 15% higher Fe and Zn contents while anti-nutritional factor “phytic acid” had decreased (M- 1.13; M+ 1.07 mg g-1). Overall, the data suggest that mycorrhizal fungal inoculation assists in biofortification kernels with Fe and Zn besides circumventing the impact of anti-nutritional factors
Male sterility induced by chemical SQ-1, as an effective male specific gametocide in maize (Zea mays)
No full textInduction of male sterility by male gametocides holds great potential in utilization of heterosis aside from nuclear
encoded male sterility (NMS) and cytoplasmic male sterility (CMS) applied in crop breeding. In the present study,
we reported a recently synthesized gametocide SQ-1, a pyridazinone derivative used for induction of male sterility
in maize. A reference dosage of chemical SQ-1 at 5.0 kg ha-1 was sprayed in five genetically unrelated maize
cultivars at the plant developmental stage L8-L10 (8 to 10 leaves developed after the above-ground seedlings),
and the results showed that the SQ-1 treated plants exhibited an intact female organ that remained vigorous to
alien pollination, and > 90% of male sterility reached by assaying pollen viability albeit fewer seeds were residually
obtained. Besides, the present data also demonstrated that the SQ-1 induced male sterility was not severely
affected by different maize genotypes. Therefore, as an alternative of NMS and CMS, the gametocide SQ-1 could
be a substitution approach in maize breeding program considering its rapidity and flexibility
Response of maize and its pest Chilo partellus to ozone and carbon dioxide exposure
Get PDFIn the present study, the direct effect of ozone (O3) and carbon dioxide (CO2) exposure on growth and yield of maize (var HQPM 1) and the indirect effect on development of its herbivore pest Chilo partellus were investigated. Maize crop was exposed to different concentrations of O3 and CO2 in open top chambers (OTCs). During the exposure, maize plants at the early vegetative stage were incubated with C. partellus eggs. Changes in biomass and yield of maize plants with and without Chilo infestation under O3 and CO2 exposure were monitored. Indirect effects of O3 and CO2 on maize pest were monitored with respect to release and survival of larvae, mean body weight of ἀfth instar stage larvae and emergence of adults from pupae. Higher reductions in aboveground and belowground biomass were observed in maize plants with pest with respect to plants without pest during O3 and CO2 exposure. Maximum and minimum reductions in aboveground (39.5% and 4.7%) and belowground biomass (43.0% and 5.4%) were observed in maize plants grown under O3 and CO2 treatments, respectively. Reduction in yield varied from 33.8% to 15.2% for maize plants grown under different treatments as compared to plants grown under low O3 conditions. Signiἀcant changes in development of C. partellus, fed on tissues of maize plants exposed to different treatments were observed. Moreover, the mean body weight of larvae decreased with increasing O3 concentrations. Mean body weight was 62% higher and 65% lower for larvae fed on maize plant tissue exposed to CO2 and CO2+EO3, respectively, as compared to maize plants grown under low O3 conditions. Development of male and female adults from pupae was observed only from larvae isolated from ambient and CO2 treated maize plants. The present study showed that the exposure of maize crop to O3 and CO2 and its pest C. partellus, adversely affected not only maize growth and yield but also development of C. partellus. This study suggests that predicting the outcome of O3 and CO2 on crop-insect pest interactions will require comprehensive examination of behavioural growth of both harmful and beneἀcial insects of the agro-ecosystem
Male sterility induced by chemical SQ-1, as an effective male specific gametocide in maize (Zea mays)
Get PDFInduction of male sterility by male gametocides holds great potential in utilization of heterosis aside from nuclear
encoded male sterility (NMS) and cytoplasmic male sterility (CMS) applied in crop breeding. In the present study,
we reported a recently synthesized gametocide SQ-1, a pyridazinone derivative used for induction of male sterility
in maize. A reference dosage of chemical SQ-1 at 5.0 kg ha-1 was sprayed in five genetically unrelated maize
cultivars at the plant developmental stage L8-L10 (8 to 10 leaves developed after the above-ground seedlings),
and the results showed that the SQ-1 treated plants exhibited an intact female organ that remained vigorous to
alien pollination, and > 90% of male sterility reached by assaying pollen viability albeit fewer seeds were residually
obtained. Besides, the present data also demonstrated that the SQ-1 induced male sterility was not severely
affected by different maize genotypes. Therefore, as an alternative of NMS and CMS, the gametocide SQ-1 could
be a substitution approach in maize breeding program considering its rapidity and flexibility
Entomopathogenic nematodes
Get PDFThe nematodes establish various and characteristic relationships with the insects; in particular the EPNs belonging to the orders Mermithida, Rhabditida, Aphelenchida and Tylenchida, show interesting association with exapods and some species are used in controlling insect pests. In particular the Steinernematidae and the Heterorhabditidae that are widely widespread in numerous habitats in almost all continents, harbor in their gut symbiotic microorganisms pathogenic for many arthropod species
Ultrastructural study on the leaf surface of four mulberry (Morus sp.) genotypes and the influence of foliar trichomes on egg layings by Spilosoma obliqua (wlk.) (Lepidoptera Arctiidae)
Get PDFA scanning electron microscopic study on the micro-morphology of four mulberry genotypes viz., Kanva2 (K2), Morus multicalis, Morus lavigata and Morus serrata was under taken to find out the influence of oviposition by the gravid females of Spilosoma obliqua (Wlk.). The results of the present study reveal that the genotype K2 was observed with minimum number of foliar non-glandular and glandular trichomes resulting in the highest number of eggs laid by the moths. On an average, a total number of eggs laid were recorded 533.44±96.02. The genotype of M. multicalis has more number of trichomes than K2 genotype and the number of eggs laid by the pest was 486.22±70.56. The genotype M. lavigata ranked third in respect of number of trichomes and oviposition and the number of laid eggs were 340.93±39.96. The leaves of M. serrata genotype were highly pubescence, therefore, in choice tests, the moths of S. obliqua did not prefer the genotype for oviposition, and this may be because of finding difficulty for the feeding organs of neonate larvae to reach the site of feeding. Statically significant difference was found among four mulberry genotypes in respect to the preference of oviposition by the moths of S. obliqua. These findings indicate that M. serrata is a source of trichome-based resistance to S. obliqua and may be of value to mulberry breeding programs attempting to expand the genetic base of host plant resistance to insect pests
