pH-Sensitive Hydrogels Based on Copolymers of Chitosan with Acrylamide and Sodium Acrylate

pH-sensitive hydrogels based on chitosan-graft-poly(acrylamide-co-sodium acrylate) were synthesized via radical polymerization in solution. Ammonium persulfate was used as initiator, and various amounts of hexamine were used as a cross-linking agent. The structure of obtained hydrogels was characterized by Fourier transform infrared spectroscopy. Moisture-absorbing power of hydrogels in buffer solution with various pH value (pH = 1.65; 4.01; 12.43) was investigated. It is turned out that such a copolymers have a high moisture retention capacity (swelling index attains the value 1100%) and are capable for reusing, that makes it possible to apply the hydrogels in different areas.

Genotype x Environmental Interaction for Growth and Yield Parameters of Tree Mulberry Genotypes in Different Seasons

Aims: To identify the stable genotypes across the seasons for different yield and its contributing traits. Study Design: Field experimental design was used Place and Duration of Study: The experiment was conducted in different seasons during 2017-19 at Department of Sericulture, University of Agricultural Sciences, GKVK, Bangalore. Methodology: The present study comprised of six mulberry genotypes viz., MI-012, MI-79, MI-21, MI-139, MI-516, ME-05 and two popular check varieties V1 and M5. Results: The mean squares due to seasons was significant for total shoot length (cm), number of leaves per plant, leaf yield per plant (g), ten fresh leaf weight (g), leaf moisture content (%) at harvest, leaf moisture retention capacity (%) at 6 and 9 hrs after harvest. Analysis of variance indicated high significance of mean sum of squares due to season for number of branches per plant, number of leaves per plant, leaf yield per plant, single leaf area, moisture content and moisture retention capacity at 6 and 9 hrs after harvest of leaf. Further, it could be observed that variance due to seasons (linear) were highly significant for number of branches per plant, total shoot length, number of leaves per plant, ten fresh leaf weight, leaf yield per plant, single leaf area, moisture content and moisture retention capacity at 6 and 9 hrs after harvest of leaf. Whereas, variance due to G х S (linear) was non significant for shoot height, internodal distance, number of leaves per plant, ten fresh leaf weight, leaf yield per plant, moisture content and moisture retention capacity at 6 and 9 hrs after harvest of leaf. Variance due to pooled deviation was highly significant for shoot height, number of branches per plant, total shoot length, internodal distance, number of leaves per plant, ten fresh leaf weight, single leaf area, moisture content and moisture retention capacity at 6 and 9 hrs after harvest of leaf. Whereas, variance due to pooled deviation was non significant for leaf yield per plant.

The effect of organic and inorganic fertilizers on soil physical condition and the productivity of a rice–lentil cropping sequence in India

A field experiment lasting 9 years was initiated in 1987 to study the effect of integrated nutrient management involving incorporation of wheat straw (WS) or farmyard manure (FYM) alone or in combination with inorganic fertilizer on a fine loamy mixed hyperthermic udic Ustochrept. Soil physical properties and the productivity of a rice–lentil cropping sequence were examined in a dry land farming system.At the end of the ninth cropping season, addition of organic materials had increased organic carbon, aggregate stability, moisture retention capacity and infiltration rate of the surface soil while reducing the bulk density. Application of inorganic fertilizer alone decreased the stability of macro aggregates and moisture retention capacity but increased the bulk density values. Treatment effects on moisture retentivity were more pronounced in the higher (0·3–1·5 MPa) suction range. During the first six experimental years, sole application of inorganic fertilizers produced 10–17% higher grain yield of rice, compared to sole application of organic sources or combined organic and inorganic sources. Annual applications of wheat straw and farmyard manure gave higher grain yields of rice from the seventh year onwards. Grain yields of lentil were higher with organic sources either alone or combined with inorganic nutrients.

Prehistoric agricultural production on Easter Island (Rapa Nui), Chile

A survey of the Easter Island landscape has resulted in the recognition of numerous lithic mulched household gardens and fields. It is proposed that lithic mulching was a technological innovation introduced to enhance the moisture retention capacity of the excessively drained island soils, and was an innovation incorporated into élite managed field systems which arose in the early 15th century to meet the demands for surplus production.