Effect of exchangeable sodium percent on surface sealing
Abstract Laboratory studies were conducted to evaluate the effect of exchangeable sodium percent (ESP) on soil surface sealing and of surface sealing on infiltration and evaporation processes. Surface seals with hydraulic conductances 52.20 × 10 −3 , 49.20 × 10 −3 , 39.00 × 10 −3 , 33.00 × 10 −3 , and 17.91 × 10 −3 h −1 were attained on top of a sandy loam soil with ESP of 4 by placing a 5-mm layer of the same soil with ESP's 6, 10, 20, 30, and 60 respectively. Surface sealing increased with increasing ESP and appeared complete at ESP 30. Evaporation remained unaffected by the seals. Infiltration, however, was considerably reduced. Soil water profiles, which largely depended on the amount of infiltrated water, tended to become uniform. Equal moisture contents were also observed under evaporation.
Improving aggregate stability of sodic sandy loam soils by organics
Abstract Laboratory studies were conducted to select a most appropriate among natural (coarse rice husk, fine rice husk, and saw dust) and among synthetic (polyvinyl alcohol, polyacrylamide, and polyvinyl acetate) organics to improve aggregate stability of the sodic sandy loam soils. Multiobjective programming applied to multi-structural index (water dispersible silt plus clay, saturated hydraulic conductivity, and modulus of rupture) identified fine rice husk and polyvinyl alcohol as the most suitable in the respective groups.
The infection process, sporulation and survival of Alternaria helianthi on sunflower
SUMMARY 
 
Electron microscopy was used to study the infection of sunflower leaves by Alternaria helianthi. Conidia germinated by producing one to many germ tubes which grew across the leaf surface before forming appressoria. The fungus directly penetrated its host through the cuticle and epidermis. Entry into the host through wounds and stomates was also observed. Extracellular sheaths were found to be associated with germ tubes and intercellular hyphae of A. helianthi. Conidiophores developed through collapsed stomates, from leaf veins, trichomes and also from mycelium growing across the host leaf surface. Microcylic conidia were produced directly from parent conidia under certain conditions. Studies using a volumetric spore trap showed that the airborne spore concentration followed a distinct periodicity with peaks occurring between 0900 and 1100 h each day. Laboratory studies showed that safflower, noogoora burr and bathurst burr could serve as alternative hosts for A. helianthi. The pathogen was readily isolated from sunflower crop debris from a diseased crop that had been harvested 1 yr earlier.