Water-stress effects on forage quality of alfalfa

Although water stress is recognized as the most important physical limitation to alfalfa yields, its effects on the nutritive quality of alfalfa have received comparatively little attention. The primary objective of this study was to characterize the responses of the nutritive quality of plant parts of alfalfa and its total herbage to water stress, occurring either throughout a growth cycle or at certain growth stages. In 1983 and 1984, alfalfa, grown in potometers, was subjected to eight irrigation treatments, and was cut at one of five harvest dates during a 7-week regrowth period. In one set of treatments, plants were irrigated to 112, 100, 88, 77, and 65% of field capacity; the other three treatments imposed water stress at one of three growth stages: late vegetative, bud, and flower;Water stress applied throughout the growth cycle reduced dry-matter yield by up to 50%, delayed plant maturity, and increased leaf-to-stem ratio (LSR). Total-herbage in-vitro digestible dry-matter (IVDDM) concentration increased by up to 7% with increasing water stress as a result of increased stem IVDDM concentration and increased LSR. Crude-protein (CP) concentration in stems increased by up to 10% while that of leaves decreased by up to 14% with increasing water stress; as a result, total-herbage CP concentration was unaffected by water stress. Cell-wall concentration (CWC) of both leaves and stems decreased with increasing water stress, causing total-herbage CWC to decrease by up to 11%. As a fraction of cell wall, lignin was unaffected, cellulose decreased, and hemicellulose increased, with increasing water stress. Effects of water stress on forage quality were generally significant even after accounting for differences in plant maturity. Most of the forage-quality differences could be related to a canopy-temperature based crop-water-stress index (CWSI);Stress at the bud and flower stages resulted in leaf wilting and leaf losses, causing a reduction in LSR by up to 40% and a deterioration in IVDDM and CP concentration of total herbage. Water stress at the vegetative stage did not significantly affect total-herbage forage quality. Because CWSI was insensitive to leaf losses caused by stress at the bud and flower stages, it did not significantly relate to total herbage forage quality although it did relate to quality of plant parts

Establishment of Desmodium ovalifolium on an ultisol

The effect of various scarification treatments on the germination of seeds of Desmodium ovalifolium (Prain) was studied. Following this a pot trial was conducted to evaluate the effects of lime, phosphorus and Rhizobium inaculation on the dry matter yield, nodulation and the nitrogen and phosphorus content in the plant. Mechanical scarification by abrasion with sandpaper improved germination by 30 percent. Liming up to the highest level of 1000 kg/ha significantly increased dry matter yield and nodulation. Phosphorus increased nodule number and phosphorus content in leaves and stems. Inoculation increased dry matter yield, nodulation and the levels of nitrogen and phosphorus in the leaves and stems

Variation of root and shoot growth and free proline accumulation in Iranian alfalfa ecotypes under salt stress

To investigate salt tolerance of 20 Iranian alfalfa ecotypes in seedling stage with emphasis on response of seedling roots and free proline accumulation, a greenhouse hydroponics trial was carried out in University Putra Malaysia. The ecotypes were representative of all climatic regions of Iran. The seeds were planted in perforated bottom trays filled with sand and immersed in nutrient solution (media culture). After 8 days when seedlings had reached the first trifoliate leaf stage the EC of nutrient solution was increased by adding sodium chloride gradually so that at 25 days of trial EC reached to 15 dS m-1. The seedlings were harvested after 29 days and observations were taken on root and shoot characteristics and free proline accumulation. The results showed different response of ecotypes in terms of root and shoot biomass and their development and also induced proline accumulation. The response of ecotypes in root parameters was variable but shoots were more affected than roots under salt stress. In the face of increasing salinity, free proline in all ecotypes increased. Eventually the results indicated that ecotypes Shorkat, Mohajeran, Rehnani, Gharghologh and Nik shahri were more tolerant than others in the seedling stage

Canola production under nitrogen fertilizer at different stages of plant growth in a crop rotation system

Nitrogen (N) fertilizer plays a vital role in enhancing canola yield. To assess the influence of nitrogen fertilizer at different stages of plant growth, an experiment was conducted at Research Farm of Agricultural Research Center in Rasht, located in Northern Iran in 2008. The experiment was laid out as a randomized complete block design with three replications. Treatments consisted of two varieties of canola (V1: Hyola, V2: PF7045.91) and five different schedules of nitrogen fertilizer application. The nitrogen treatments comprised of application of a total of 300 kg nitrogen using five different schedules of application: N1 (150 kg/ha at planting time and 150 kg/ha at flowering time), N2 (100 kg/ha at planting time, 100 kg/ha after rosette stage and 100 kg/ha at flowering time), N3 (150 kg/ha at planting time, 75 kg/ha 30 days after planting, 75 kg/ha at flowering time), N4 (75 kg/ha at planting time, 150 kg/ha after rosette stage and 75 kg/ha at flowering time), N5 (conventional schedule of nitrogen fertilizer in the region comprising of 75 kg/ ha at planting time, 75 kg/ha 30 days after planting, 75 kg/ha after rosette stage and 75 kg/ha at flowering time). Results showed that the highest seed yield (3597 kg/ha) of canola was obtained from variety PF7054.91 and the best programme of nitrogen fertilizer was N4 where 75 kg N/ha was applied at the planting time, 150 kg N/ha after rosette growth stage and 75 N kg/ha of nitrogen at the flowering time. Production efficiency of canola crop can be enhanced in a crop rotation system in rice farms under agro-ecological conditions of Guilan, North of Iran

Phenotypic and genotypic variation of Brachiaria decumbens after exposure to gamma radiation.

An experiment was conducted to evaluate the phenotypic and genotypic variations of pasture grass Brachiaria decumbens Stapf after irradiation with gamma rays. About 1 kg B. decumbens seeds were subjected to gamma irradiation at 900 Gy. The irradiated and untreated seeds were sown in a potting media mixture. After one week, the seedlings were thinned to leave only one seedling in each hole. Cutting back method was applied to eliminate chimeric sector in the plant. Subsequent cutting back of stolons was carried out up to M1V6 (6th cutting back). A distinctly different phenotype of B. decumbens was discovered amongst the irradiated seedling. This individual phenotype was multiplied and observations were recorded and comparedwith the control. The phenotype presumed as mutant had an erect growth habit, short internodes and profuse tillers. The leaves were darker green and they had finer hairs as compared to the control plants. The mutant leaves were also wider and shorter than the control plants. The leaf to stem ratio was also greater in the mutant. The nutritive characteristics between the mutant and control plants were similar, with the exception that the mutant had a significantly greater crude protein concentration (20.07%) as compared to control (18.86%). Random Amplified Polymorphic DNA (RAPD) assay using single arbitrary primer CS1786 and CS1787 showed that the primer CS1786 generated more than four strongly amplified bands of DNA with sizes ranging from 500 bp to 1500 bp. The assay showed that there was no difference between the DNA profiles of mutant Brachiaria decumbens and its mother plant. This work shows that the technique of gamma irradiation can be used to increase phenotypic diversity of B. decumbens that could be applied in breeding programs

Yield and agronomic characteristics of tropical rice as influenced by high nitrogen rates

An experiment with treatments comprising of five nitrogen rates (0, 120, 160, 200 and 240 kg N/ha) applied as urea was carried out to evaluate the effects of high nitrogen application on the yield and agronomic performance of two rice varieties; MR 211 and MR 219. Raising nitrogen application was found to increase (P<0.05) the number of spikelets per panicle but reduce the percentage of filled spikelets (P<0.05). Although the increment in number of spikelets per panicle resulted in the reduction of the filled spikelets percentage, the grain yield was not affected due to sufficient production of spikelets per square meter which maintained the grain productivity. The plant agronomic characteristics such as stem height and duration to grain maturity also increased (P<0.05) with nitrogen application. Both varieties differ in the yield components and agronomic characteristics. Between the two varieties, MR 219 is superior to MR 211 in view of the higher grain yield and grain: straw ratio. The result from correlation between yield and yield components implies that the total number of spikelets per square meter was believed to be the major determinant of grain yield

Effect of combined application of poultry manure and inorganic fertiliser on yield and yield components of maize intercropped with soybean

A field experiment was conducted to evaluate the effect of the combined application of poultry manure and inorganic fertiliser on yield and the yield component of maize (Zea mays L) and soybean (Glycine max L. Merril) intercrops. Treatments comprised combinations of three intercropping systems (sole maize, sole soybean and maize+soybean) and four nutrient management practices [control, 100% NPK, 100% poultry manure (PM) and 50 % NPK+50% PM]. The experiment was laid out in a randomised complete block design (RCBD) with three replications. The results revealed that intercropping of maize with soybean significantly reduced soybean yield and yield components, but maize yield and yield traits were not significantly affected by intercropping. Land Equivalent Ratio (LER) was >1, indicating a beneficial effect of intercropping soybean with maize. For both maize and soybean, there were no significant differences in yield between application of 100% NPK and the 50% NPK+50% PM fertiliser. A combined application of 50% NPK and 50% PM gave the highest monetary advantage in intercropping system. It can be concluded that a 50% substitution of inorganic fertiliser with poultry manure is recommended to reduce use of chemical fertilisers without sacrificing crop yield

Fermentation characteristics and nutritive value of corn silage intercropped with soybean under different crop combination ratios

Corn silage is an important feed for intensive ruminant production. Combining corn with legumes for silage is a feasible strategy to improve crude protein (CP) concentration in corn silage. This study was conducted to determine silage nutritive quality and fermentation profiles of corn grown in mixture with soybean at different crop combination ratio. In this experiment, corn-soybean combinations of 75:25, 50:50 and 25:75 in addition to monocrops of corn and soybean were evaluated. The crop combination ratio had significant effects on nutritive quality and fermentation characteristics of silage. Silage quality in terms of CP (75:25 ratio 12.23%, 50:50 ratio 12.88% and 25:75 ratio 13.65%) was improved by intercropping compared with corn sole crop (9.91% CP). Increase ratio of soybean resulted in an increase in lactic acid and pH of the mixed silage. Sole soybean gave significantly higher lactic acid (3.57%) and pH of silage (4.33) compared to all other treatments but dry matter concentration was significantly higher in corn monocrop silage (34.34%) than other treatments. The propionic acid and butyric acid content of soybean monocrop and intercrops silage were in all cases higher than sole corn silage

Evaluation of mulberry (Morus alba) as potential feed supplement for ruminants: the effect of plant maturity on in situ disappearance and in vitro intestinal digestibility of plant fractions

The in situ nylon bag degradation and in vitro intestinal digestibility of dry matter (DM), and crude protein (CP) of mulberry (Morus alba) plant fractions was studied at four harvest stages, 3 (W3), 5 (W5), 7 (W7) and 9 (W9) weeks. Degradability of DM and CP of the whole plant and stem fractions declined significantly (pW5 and W7>W9 and W3>W5>W7>W9, respectively. The degradation of DM and CP of the leaf fraction was also influenced by plant maturity but no trend was observed. The degradation of DM and CP of the whole plant and leaves increased rapidly during the first 48 and 24 h of incubation, respectively, when maximum degradation was reached. In vitro intestinal digestibility of CP was more influenced by the residence time in the rumen than by plant maturity. This study showed that mulberry is suitable as a supplement, particularly to low-quality roughages, in providing a source of rapidly available nitrogen to the rumen microbes, hence improving the roughage degradability and intake