A greenhouse experiment was conducted to understand the seedling germination behaviour and growth of sorghum genotypes, to investigate genotypic differences between sorghum genotypes and to identify a selection method for seedling drought resistance studies in sorghum under variable soil moisture deficit conditions. The experimental design used was a split plot design with four soil moisture deficit treatments (25%, 45%, 65% and 85% of field capacity) as main plot treatments and five sorghum genotypes (76 T1 #23, (148xE-35-1)-1-4-1xcs 3541 drive-5-3-2, M36121, 12x34/F4/3/E/1 and IS2284) as subplot treatments. Sorghum genotypes differed significantly in response to variable soil moisture deficit for percentage germination, seedling shoot dry weight, specific root length and seedling leaf area. The percentage germination of all genotypes was markedly reduced by increasing the levels of soil moisture deficits. Among the genotypes 76 T1 #23, M36121 and IS2284 had a satisfactory percentage germination at 25% of field capacity (F.C.), ranging from 55–57% germination based on arc sin transformed data. The seedling shoot dry weight of all genotypes was also significantly (p<0.05) reduced at all levels of soil moisture deficits, except in IS2284 where there was an increase of 3.6% at 65% of F.C. relative to the control. Although the interaction effects for seedling shoot and root lengths were not significant, IS2284 had the longest seedling shoot and root lengths and this is a desirable trait related to drought resistance. It has been observed that the reduction in seedling shoot length was greater than that of seedling root length at all levels of soil moisture deficit treatments, indicating that extensive root growth under drought conditions is a major avoidance mechanism in sorghum. Genotypes were also found to have differential responses to variable soil moisture deficits for their specific root length and leaf area. Based on the results of this study, percentage germination, seedling shoot dry weight, specific root length and seedling leaf area may be used as potential selection criteria for seedling drought resistance studies in sorghum and further studies are required to confirm this result under field conditions.
Sustainable land use
and rational soil management, including an up-to-date soil moisture control
requires continuous actions. This permanent control may prevent, eliminate or
at least reduce undesirable soil processes and their harmful
economical/ecological/environmental/social consequences; utilizing the unique
soil characteristic, resilience, may satisfy the conditions for the “quality
maintenance” of this “conditionally renewable” natural resource. Control can be
efficient only on the basis of comprehensive risk assessment, impact analysis
and exact prognosis. These have to be the main research priorities! The
successful prevention, elimination or moderation of undesirable soil
degradation processes and extreme moisture regimes can be efficient only in a
well-coordinated multidisciplinary international cooperation in the Carpathian
Basin. The realization of the sustainability concept in the rational land use
and soil management gives reality for a better life: healthy, good quality
food, clean water and pleasant environment.
HALLE-WITTENBERG, HALLE(SAALE), GERMANY Received: 13 June, 2001; accepted: 6 August, 2001 Field experiments were conducted at a high latitude site for sunflower (Helianthus annuus L.) production in central Germany (51 o 24' N, 11 o 53' E) in 1996, 1997 and 1998. The responses of sunflower development to various planting patterns differed in the duration from emergence to the middle of the linear growth period as calculated via a tangent hyperbolic model F(t)=(. +ß)×tanh[. ×(t–.)]. Final dry matter accumulation showed few differences among the planting patterns: 12 plants m –2 at 50 cm row spacing at 75 cm row spacing (RS2PD2) and 4 plants m –2 at 100 cm row spacing (RS3PD1). The actual and simulated values for final dry matter were close to 1200 g m –2 . The responses of soil moisture and temperature to planting patterns changed from the upper to the deep soil layers. In a normal year, e.g. 1997, the soil water to 150 cm depth was sufficient for sunflower growth. In a drought year, e.g. 1998, soil water deeper than 150 cm was used by sunflower crops. The soil temperature was mostly lower in RS1PD3 and RS2PD2 than in RS3PD1, particularly in the upper soil, at depths of 5 and 20 cm. The most important factor defining the responses of soil moisture and temperature to planting patterns seems to be the amount of radiation penetrating the ground, which may depend on latitude, wind and row orientation.
Selection on the basis of grain yield
for improved performance under excessive moisture stress has often been misleading and considered inefficient. We assessed the importance of secondary traits of adaptive value under waterlogging stress. During the 2000–2004 summer-rainy seasons twelve trials were conducted and a total of 436 tropical/subtropical inbred lines (S
) were evaluated under excessive soil moisture stress. Excessive moisture treatment was applied at V
growth stage by flooding the experimental plots continuously for seven days. Different phenological and physiological parameters were recorded before, during and either immediately or 1–2 weeks after exposure to stress. Excessive moisture conditions significantly affected all the morphological and physiological traits studied. However, there was significant genetic variability for various traits, especially for root porosity and brace root development that were induced under excessive moisture. Across the trials, significant genetic correlations (p<0.01) was obtained between grain yield and different secondary traits, including ears per plant, root porosity, brace root fresh weight, number of nodes with brace roots and anthesis silking interval. Broad-sense heritability decreased under excessive moisture stress conditions for most of the traits; however, it increased significantly for root porosity, nodal root development and ears per plant. Our findings suggest that consideration of these second-ary traits during selection of maize germplasm for excessive moisture tolerance can improve selection efficiency and genetic gains.