Tag Archives: leaf area index

320-334 S.C. Malaza and T. Tana
Agronomic and physiological response of maize (Zea mays L.) hybrids to plant density in the dry and wet Middleveld of Eswatini
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Agronomic and physiological response of maize (Zea mays L.) hybrids to plant density in the dry and wet Middleveld of Eswatini

S.C. Malaza and T. Tana*

Department of Crop Production, University of Eswatini, P. O Luyengo, M 205, Eswatini
*Correspondence: tamado@uniswa.sz

Abstract:

One of the factors limiting yield of maize in Eswatini is use of non-optimum plant density for the different maturity group of maize hybrids in different agro-ecologies. Thus, an experiment was conducted at Malkerns (wet Middleveld) and Luve (dry Middleveld) in Eswatini to determine the effects of plant density on growth, yield components and grain yield of maize hybrids. Factorial combinations of three maize hybrids [SC 403 (early maturing), SC 621 (medium maturing), SC 719 (late maturing)] and five plant densities (41,667; 44,444; 47,619; 50,000, and 57,143 plants ha^-1) were evaluated in Randomised Complete Block Design in three replications. The results showed that Malkerns had significantly higher crop growth rate (CGR) between V12 and R6 growth stages, relative growth rate (RGR) between V6 and V12 growth stages, mass of thousand kernels (395.60 g), aboveground dry biomass (22.71 t ha^-1) and grain yield (7.67 t ha^-1). Among maize hybrids, SC 719 produced significantly the highest CGR (18.37 g m^-2 per day) between V12 and R6, aboveground dry biomass (23.05 t ha^-1), number of kernels per m² (2074), and grain yield (7.49 ha^-1). Moreover, SC 719 grown at Malkerns recorded significantly the highest leaf area index (LAI) at V6, and the highest CGR (31.35 g m^-2 per day) between V6 and V12 and the tallest plants. The highest density of 57,143 plants ha^-1 produced the highest LAI, aboveground dry biomass (21.53 t ha^-1) and grain yield (7.17 t ha^-1). Thus, late maturing maize hybrid SC 719 and plant density of 57,143 plants ha^-1 (70 cm × 25 cm) can be used to enhance the productivity of maize in the Middleveld of Eswatini.

Key words:

crop growth rate, grain yield, leaf area index, relative growth rate, Swaziland, yield components

21-30 V. Eremeev, A. Lõhmus and J. Jõudu
Effects of thermal shock and pre-sprouting on field performance of potato in Estonia
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Effects of thermal shock and pre-sprouting on field performance of potato in Estonia

V. Eremeev, A. Lõhmus and J. Jõudu

Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences(EMU), Kreutzwaldi 64, EE51014 Tartu, Estonia;e-mail: Viacheslav.Eremeev@emu.ee

Abstract:

Pre-sprouting (PS), and to a lesser degree, pre-planting thermal shock (TS) had positive effects on tuber yield and other performance indicators. The experiment was carried out during the 2000, 2001 and 2002 growing seasons in the Department of Field Crop Husbandry of the Estonian University of Life Sciences. An untreated control (0) was comparedοοwith TS (2 days at 30 C, then 5 days at 12–15 C in a lighted room just prior to planting) and PSο(35–38 days before planting in a humid (85–90%) and lighted room at 12–15 C). All treatments were applied to three varieties: ‘Agrie Dzeltenie’ (early), ‘Piret’ (medium early) and ‘Ants’ (medium late). In the present study, the TS accelerated the emergence of plants by 2–5 days and PS by 7–12 days. Averaged over 3 years and 3 varieties, maximum leaf area index (LAI, 3.9 units) was reached 74 days after planting (DAP) and on the 50th day after emergence. Maximum LAI was 3.7 at 72 DAP for PS, 3.8 at 73 DAP for TS, and 4.1 at 76 DAP for the control. TS accelerated the beginning of tuber formation by about 5 days compared to the control, but the tuber yield of the control equalled TS from 65 days onward. Tuber formation began even slightly earlier in the PS treatment, and tuber yield exceeded PS throughout the season. All treatments reached maximum yield by 120 DAP.

Key words:

dynamics, growth analysis, haulms, LAI, leaf area index, tuber yield

293-297 A. Marcinkevičienė, S. Raudonius and R. Velička
Weed suppression by increasing spring rape crop density
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Weed suppression by increasing spring rape crop density

A. Marcinkevičienė, S. Raudonius and R. Velička

Lithuanian University of Agriculture, Studentu 11, Akademija, Kaunas district, LT-53067,Lithuania, e-mail: lzuustotis@hotmail.com, steponas.raudonius@lzuu.lt

Abstract:

Field experiments were conducted in 2003 and 2004 at the Experimental Station of the Lithuanian University of Agriculture to study the influence of different spring rape (Brassica napus L.) densities (50.1–100, 100.1–150, 150.1–200, 200.1–250, 250.1–300, 300.1–350, 350.1–400, 400.1–450 plants m-2) on weed abundance. Increase of crop density and herewith increase of canopy should intensify the competition ability of spring rape plants and suppress weeds better. The results show that light intensity on the soil surface decreases when the assimilation area of spring rape leaves and total crop biomass increases. Weed density decreases when spring rape crop is densier. A significant negative relationship exists between weed biomass and spring rape leaf area index (LAI) (r = -0.62, P < 0.05), as well as between weed biomass and spring rape biomass (r = -0.67, P < 0.01). A significant positive correlation appears between weed abundance and light intensity on soil surface (r = 0.68, P < 0.01).

Key words:

Brassica napus, crop density, leaf area index, lighting, weed suppression