NITROGEN HARVEST INDEX AND ITS ASSOCIATION WITH CROP YIELDS

Nitrogen (N) is one of the most yield-limiting nutrients in crop production around the world. The main reasons of N deficiency are low recovery efficiency (RE) of applied N fertilizers. The RE efficiency of N by most crop plants is lower than 50%. The lower RE of this element is associated with losses by volatilization, leaching, denitrification, and soil erosion. Some part of N is also immobilized in undecomposed organic materials and by soil microbial population. Nitrogen harvest index (NHI) is a ratio between N accumulated in grain to N accumulated in grain plus straw. The NHI is an important index in determining crop yields because it is positively associated with grain yield. Relationship between GHI and crop grain yield may be positive linear or quadratic depending on crop genotypes and soil and crop management practices adopted. In cereals retranslocation of previously assimilated N in the vegetative parts is the predominant source of N for the grain. The most important practices that can improve NHI are liming acid soils, use of adequate N rates, source and timing, planting N efficient crop species or genotypes within species, and use of appropriate crop rotation.     

Distribution of Chromium,Nickel, and Cobalt in Different Parts of Plant Species and Soil in Mining Area of Keban,Turkey

Abstract

The distribution of chromium, nickel, and cobalt in the plant species and soil of the Zn‐Pb‐Ag sulfide deposits of the Keban area in Turkey have been studied to determine both biogeochemical indicators and biomonitoring of environmental pollution. Plants, including Euphorbia, Verbascum, and Astragalus, and their associated soil samples were collected, and the roots and shoots of these plants together with soils were analyzed by inductively coupled plasma‐mass spectrometry (ICP‐MS). The three metal concentrations in the shoots of Euphorbia samples were found to be lower than in their roots, whereas the metal concentrations in shoots of Verbascum are higher than in their roots. Although the metal concentrations in soils were found to be lower than the permissible limits for agricultural purposes, the concentrations of these metals in different parts of some plants were observed at excessive/toxic levels. As a result, the roots of Euphorbia and the shoots of Verbascum and Astragalus can be used to biomonitor environmental contamination and as biogeochemical indicators.     

Morphophysiological and Grain Yield Responses to Foliar and Soil Application of Boric Acid on Soybean

ABSTRACT

Boric acid (H₃BO₃) fertilization as source of boron (B) is a common practice in modern agriculture, aims to correct the deficiency of this micronutrient in the Cerrado soils, and ensure the maintenance of plant metabolism for the proper crops’ development. Therefore, the aim of this work was to evaluate the effects of H₃BO₃ fertilization on soil and leaves during the soybean development. The experimental design was completely randomized with six replicates. The treatments were obtained in a 3 × 2 factorial scheme, fertilization with H₃BO₃ for three doses of B in the soil: 0 (control); 0.62 and 3.4 kg ha^?1 and two foliar supplementation conditions: absence and presence. The best results for the variables length, dry mass and leaf area of soybean plants occurred with B applied to soil at doses 0 and 3.4 kg ha^?1 in the absence of foliar supplementation. B content in the plants gradually increased with the micronutrient supply via soil and in leaves. Physiological apparatus of the plants was more efficient in the absence of foliar supplementation, independently of the fertilization with doses in the soil. The grain mass was up to 57% higher in the control treatment. Fertilization with H₃BO₃ in the soil and foliar did not improve the morphophysiological traits and the production of soybeans grown in greenhouse using clayey soil with initial B content of 0.30 mg dm^?3.     

Effets des engrais N,P et K sur le rendement et la qualite de l'ensilage ue mais

Abstract

Thirteen fertility trials were made throughout Quebec's corn growing region during 1972–74. These included eleven fertilizer combinations with corn silage as the test crop and were carried out on nine soils. Total dry matter and digestible nutrients (TDN) varied greatly from year to year, though, mean yields increased by 23 and 30 percent respectively with the 50 kg N/ha treatment, compared to control receiving no nitrogen fertilization. However, 150 kg N/ha was required to attain a maximum yield of 1250 kg/ha crude protein. Despite a 0.2 percent nitrate content found in the silage grown on the most northerly site, a 120 kg P/ha combined with 100 kg N and K gave the highest mean TDN production (9580 kg/ha).

Potassium fertilization affected plant K content of corn grown at the most northerly site only, where a 0.5 percent was found with the control on a suit containing low potassium levels. Further, striking increases in Ca and Mg concentrations were observed with corn grown on that soil. However, magnesium concentration ranging from 0.11 to 0.14 percent were found with nine field trials out of twelve. Also, low K:(Ca + Mg) ratios were found on three trials, which were increased with potassium fertilization levels of 150 kg K/ha. Accordingly, it is suggested that uptakes of 200, 48, 200, 30 and 30 kg/ha of N, P, K, Ca and Mg are required for good corn silage crops.     

Influence of irrigation and growth stage on element concentrations of soybean plant parts

Abstract

A three‐year field study was conducted to determine the influence of irrigation on the nutrition of the “Lee 74” cultivar, a determinate soybean (Glycine max (L.) Merr.). The objectives were to measure seasonal concentrations of N, K, Ca, and Mg in steins, leaves, and pods for soybeans grown on a Crowley silt loam (Typic Albaqualf) and a Kobel clay (Vertic Fluvaquent) under irrigated and nonirrigated moisture regimes. Fluctuations in element concentrations in relation to plant growth stage for irrigated and nonirrigated leaves and stems were modeled using multivariate regression. Elements in the pods as effected by irrigation and growth stage were also compared.

During 1974, a wet year, element concentrations of the leaves, stems, and pods were unaffected by irrigation. In the dry years of 1975 and 1976, significant differences in the concentration of N, K, Ca, and Mg in the plant component parts were found due to irrigation. Generally, element concentrations of stems, leaves, and pods of irrigated plants were greater than those of water‐stressed stems, leaves, and pods at several growth stages. Element concentrations in stems and leaves that were significantly affected by irrigation also were reflected in the pods, Regression models generally accounted for the majority of the seasonal element variation. Irrigation improved the predictability of the K and Ca regression models.     

The DRIS for interpretation of coastal bermudagrass analysis

Abstract

Diagnosis and Recommendation Integrated System (DRIS) norms for N, P, K, Ca, Mg, and S were developed for three high‐yield Coastal bennudagrass populations that were selected from soil fertility studies that contained six rates each of N, P, and K. Norms from the high‐yield population that was based on a single yield level at a given harvest date were considered most suitable. The relative importance of criteria used to select suitable diagnostic parameters was discussed along with composition of index equations. The norms developed from Coastal bennudagrass grown on an Aquic Fragiudalf soil in south Louisiana accurately predicted yield responses to N, P and K applications at that location and to P, S, and Mg applications on Typic Paleudult soils in north Louisiana. A computer generated DRIS balance chart was designed to provide a visual interpretation of individual sets of DRIS indices.     

Influence of total soluble salt concentration on growth and elemental concentration of winged bean seedlings,Psophocarpus tetragonolobus (L.) DC.

Abstract

Winged bean (Psophocarpus tetragonolobus) (L.) DC) seedlings of the accession TPT‐1, were grown in a greenhouse with graded, balanced total soluble salt (TSS) concentrations. After 4.5 days, plant height increased quadratically, with a maximum (149 cm) at 3000 ppm TSS. Seedlings were shortest at 1000 and 10,000 ppm TSS, 44.0 and 79.0 cm, respectively. Fresh weight of shoots increased quadratically with greatest weight, 29.03 g, at 5000 ppm TSS. Percent dry matter increased linearly with increasing TSS. Concentration of N, K and P increased quadratically with an increase in the TSS concentration in the growth medium. Concentration of Ca decreased quadratically with increasing TSS. Among the micronutrients, Fe and Mo concentration was quadratic, both elements were highest in the seedlings at 1000 and 10,000 ppm TSS rates. Concentrations of Mn and Zn increased linearly with increasing TSS. Winged bean seedlings at the 1000 to 3000 ppm TSS rates had spindly stems and a sparse, yellow foliage, typical for winged bean seedlings observed in the field during the first 4 to 5 weeks of growth. Seedlings at the 4000 and 5000 ppm TSS rates had sturdy stems and an abundant green foliage. At higher TSS concentrations, 5000 to 10,000 ppm TSS, seedlings had short intermodes and dark green foliage.     

Intra-varietal variation for in vitro plant regeneration in the genus Trifolium

Summary Seedlings of Trifolium repens showed considerable variation with regard to the morphology and growth of their calli, and their ability for in vitro differentiation of shoots. One of the lines selected for regeneration in primary callus cultures also showed shoot formation from protoplasts. Somatic embryogenesis in callus cultures of T. pratense and T. arvense occurred only in selected seedling lines. This paper highlights the importance of screening a large number of plants within a cultivar of outbreeding species to achieve reproducible plant regeneration from tissue culture.