Analysis of the regrowth of a tropical grass/legume sward subjected to different frequencies and intensities of defoliation

1980 ◽  
Vol 31 (4) ◽  
pp. 673 ◽  
Author(s):  
MM Ludlow ◽  
DA Charles-Edwards
Keyword(s):  
Leaf Area ◽  
Dry Matter ◽  
Dry Weight ◽  
Light Interception ◽  
Photosynthetic Characteristics ◽  
Dry Matter Production ◽  
Canopy Photosynthesis ◽  
Area Index ◽  
Matter Production ◽  
Cutting Height

Dry weight, leaf area, light interception and canopy photosynthesis were measured during 3- or 5-week regrowth periods of Setaria anceps/Desmodium intortum swards cut to 7.5 or 15 cm. Dry matter production during the experiment and over the growing season increased with cutting height and with interval between defoliations, but the proportion of grass to legume was unaffected. These effects of defoliation on dry matter production were similar to those estimated for integrated canopy photosynthesis from measured light interception and calculated leaf photosynthetic characteristics. Height and frequency of defoliation had no effect on canopy extinction coefficient for light, nor on the leaf photosynthetic characteristics, except for the first 1-2 weeks after defoliation when leaf photosynthetic rates appeared to be depressed. The main effects of height and frequency of defoliation on dry matter production were through their effects on leaf area index and light interception.

The growth and performance of cotton in a desert environment: II. Dry matter production

1969 ◽  
Vol 73 (1) ◽  
pp. 75-86 ◽  
Author(s):  
A. B. Hearn
Keyword(s):  
Growth Rate ◽  
Dry Matter ◽  
Initial Period ◽  
Dry Weight ◽  
Dry Matter Production ◽  
Area Index ◽  
Vegetative Phase ◽  
Matter Production ◽  
Sink Size ◽  
And Performance

SUMMARYVariety, water and spacing were treatments in two experiments with cotton in 1963 and 1964 in which fruiting points, flowers and bolls were counted and the dry weights and leaf areas of plants were measured at intervals during the season.Until leaf-area index, L, started to decrease, the equation described how dry weight, W, changed. The equation gave smoothed estimates of crop growth rate, C, which were consistent with estimates of photosynthesis made with de Wit's (1965) model. The relationship between G and L conformed to , derived from Beer's Law, rather than C = aL — bL2 derived from the linear regression of E on L. When L > 3 the crop appeared to use most of the available light, so that C approached a maximum. Treatments initially affected dry-matter production through the numbers and types of branches and nodes, which in turn affected the sinks available and thus the proportion of dry matter reinvested in new leaf. This initial period, when growth was simple to describe in conventional terms, was denned as the vegetative phase of growth.The start of the reproductive phase of growth overlapped the vegetative phase. The change from one to the other was completed when the rate of dry weight increase of the bolls, CB, equalled C. This indicated that the sink formed by the bolls had increased sufficiently in size to use all the assimilates available for growth. Sink size increased as the crop flowered and was estimated from the product of the number of bolls and the growth rate of a single boll.When CB equalled C, bolls were shed which prevented the size of the sink to increase beyond the ability of the plant to supply it with assimilates. This agrees with Mason's nutritional theory of boll shedding. Because of the crop's morphology and because age decreased the photosynthesis of the crop, the size of the sink inevitably increased out of phase with the supply of assimilates. The extent to which this was so determined when CB equalled C. It is postulated that environment, genotype and agronomic practice affect yield according to whether they increase or decrease the extent to which the sink size and the supply of assimilates are out of phase.

The growth of swards of subterranean clover with particular reference to leaf area

1958 ◽  
Vol 9 (1) ◽  
pp. 53 ◽  
Author(s):  
JL Davidson ◽  
CM Donald
Keyword(s):  
Leaf Area ◽  
Dry Matter ◽  
Substantial Reduction ◽  
Ground Surface ◽  
Subterranean Clover ◽  
Climatic Conditions ◽  
Dry Matter Production ◽  
Leaf Production ◽  
Area Index ◽  
Matter Production

An experiment was conducted to study the growth of subterranean clover (Trifolium subterraneum L.) sown at different densities; the control swards were not defoliated while others were subjected to a single defoliation at various dates. During the final month the rate of dry matter production (tops only) increased to a maximum when the leaf area index (the ratio of the area of the leaves to the area of the ground surface — L.A.I.) was about 4-5, falling by about 30 per cent. as the L.A.I. increased to 8.7. The rate of leaf production was greatest at about L.A.I. 4-5, falling to zero at L.A.I. 8.7. Climatic conditions during the growing season influenced the relationship of L.A.I. to growth; as conditions became more favorable the values of the optimum LA.1. for growth and of the ceiling L.,4.1. progressively rose. Irrespective of the density, all swards tended towards a common ceiling L.A.I. and yield by the end of the season. The effect of defoliation depended on the L.A.I. at which defoliation occurred, on the value to which the L.A.I. was reduced, and on current climatic conditions. If swards near the ceiling L.A.I. were defoliated, total dry matter production was slightly increased and there was a great increase in leaf production. On the other hand, defoliation of swards from about the optimum L.A.I. to very low L.A.I. values led to a substantial reduction in both dry matter and leaf production. It is suggested that all these effects depend on the light relationships within the sward and their influence on the balance of photosynthesis and respiration. Pasture at the optimum L.A.I. will give greater production than swards of lower or higher L.A.I.; defoliation can give greatly increased leaf production, unless L.A.I. is reduced to very low values.

scholarly journals EVALUATION OF EARLY POST-EMERGENCE HERBICIDE APPLICATION ON WEED CONTROL, CROP GROWTH AND NUTRIENT UPTAKE IN TRANSPLANTED RICE (ORYZA SATIVA)

2020 ◽  
Vol 21 (supplement 1) ◽  
Author(s):  
T. Srinithan ◽  
K. Arivukkarasu Arivukkarasu ◽  
P. Sivasakthivelan ◽  
R. Rex Immanuel
Keyword(s):  
Leaf Area Index ◽  
Nutrient Uptake ◽  
Leaf Area ◽  
Plant Height ◽  
Weed Control ◽  
Dry Matter ◽  
Dry Matter Production ◽  
Area Index ◽  
Transplanted Rice ◽  
Matter Production

A field experiment was conducted during Kuruvai season at the Experimental Farm, Department of Agronomy, Annamalai University to evaluate the performance of early post emergence application of herbicides on weed control in transplanted rice. The experiment was carried out in a Randomized Block Design with eight treatments and three replications. All the imposed treatments significantly influenced the weed parameters and crop parameters in rice. The experimental results revealed that, hand weeding twice at 20 and 40 DAT recorded the lowest total weed count (13.74), highest weed control efficiency (WCE) (92.79 per cent), highest plant height (85.76 cm), higher leaf area index (4.28), higher crop dry matter production (7689 kg ha-1 )and highest nutrient uptake by rice crop (134.79, 33.17, 99.41 kg of N, P2O5 , K2O ha-1, respectively) which was statistically on par with application of penoxsulam + cyhalofop butyl@135 g ha-1 (premix)(15 DAT) that recorded the total weed count (16.74), weed control efficiency (91.21 per cent), plant height (85.03cm), leaf area index (4.19), dry matter production (7567 kg ha-1), crop nutrient uptake (132.37 , 32.48, 97.25 kg of N, P2O5 , K2O ha-1, respectively). Highest total weed count, with lowest plant height, leaf area index, crop dry matter production and crop nutrient uptake were recorded with unweeded control.

scholarly journals Integrated Nutrient Management with Biofertilizers in Different Genotypes of Rice Sown under Aerobic Conditions

2019 ◽  
pp. 1-8
Author(s):  
B. Sreedevi ◽  
Aarti Singh ◽  
M. Tejaswini
Keyword(s):  
Leaf Area Index ◽  
Nutrient Uptake ◽  
Leaf Area ◽  
Dry Matter ◽  
Nutrient Management ◽  
Growth And Yield ◽  
Dry Matter Production ◽  
Area Index ◽  
Yield Attributes ◽  
Matter Production

Aerobic rice is a new way of cultivating rice that requires less water than lowland rice. A field experiment was conducted during the kharif season of 2015 to evaluate the effects of nutrient management with Biofertilizers on growth and yield attributes, yield, nutrient uptake and economics different rice cultivars. The experiment was laid out split plot design with four replications. Main plot treatments consisted of two cultivars viz., whereas, sub plot treatments comprised of nutrient management practices namely, N1-125% RDF, N2-125% RDF + Biofertilizers, N3 -100% RDF, N4 -100% RDF + Biofertilizers, N5-75% RDF, N6-75% RDF + Biofertilizers. The source of biofertiliser was a combination of Azospirillum, Phosphorus Solubilizing Bacteria and Potassium Solubilizer applied @ 5 kg/ha-1. Crop dry matter production (2582.3 g/m2), root dry matter production (910.1 g/m2), tillers/m2 (566), leaf area index (4.54), panicles/m2 (535), panicle length (23.81), panicle weight (4.56) and test weight (25.3) was higher in PA 6444 compared to DRR Dhan 44. Higher uptake of nutrients was also observed in PA 6444. Rice fertilized with 125% RDF + Biofertilizers (N2) produced higher crop (2901.6 g/m2) and root dry matter production (1028.1 g/m2), tillers/m2 (561) and leaf area index (5.19). This treatment also recorded higher yield attributes and grain yield (3.55 t/ha). With respect to nutrient uptake, application of 125% RDF + Biofertilizers (N2) recorded      higher N, P and K uptake by grain and straw and higher profitability (1.57) than other nutrient combinations.

GROWTH AND DRY MATTER (FODDER) PRODUCTION OF MAIZE (Zea mays L.) VARIETIES AS AFFECTED BY TIMING OF NITROGEN SECOND DOSE FERTILIZATION

2021 ◽  
Vol 4 (4) ◽  
pp. 96-107
Author(s):  
Muhammad Kabir Ladan ◽  
Hassan Adamu Hamidu ◽  
Abdul Bamidele Lawal ◽  
Abdullahi Namakka
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Sea Level ◽  
Dry Matter ◽  
Dry Matter Production ◽  
Total Leaf Area ◽  
Area Index ◽  
Matter Production ◽  
Maize Varieties ◽  
Number Of Leaves

ABSTRACT Field trials were conducted in 2016 wet season at Institute of Agricultural Research IAR, Research Farm(Lat.11o 11’ N, Long. 07038’ E, 686m above sea level), Samaru-Zaria and Jaji Military Cantonment Farm located at 30 Km from Zaria along Kaduna – Zaria road (Lat. 10o 49’ 25” N, Long. 07o 34’ 10” E, 600m above sea level), both in Northern Guinea Savannah of Nigeria, to Investigate the growth of Maize varieties and dry matter produced at varying timing of nitrogen second dose fertilization. The treatments consist of three maize varieties (SAMMAZ 14, SAMMAZ 15 and SAMMAZ 16) and six times of nitrogen second dose fertilization 4 5, 6, 7, 8, 9 weeks after sowing (WAS). Treatments were factorially combined and laid out in a randomized complete block design (RCBD) with three replications. SAMMAZ 16 outperformed SAMMAZ 14 and SAMMAZ 15 in terms of plant height, number of leaves, total leaf area, leaf area index and dry matter production. Time of nitrogen second dose application 6 WAS consistently produced the highest growth attributes of maize  ;plant height, number of leaves, total leaf area, leaf area index and dry matter production compared to other timings evaluated. SAMMAZ 16 and 6 WAS in conclusion appeared to be the optimum for increased maize fodder (dry matter) production in the Savannah region where potential for livestock production is high.

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