ALBERT

Description: Infiltration is the most important aspect in the hydraulics of surface irrigation, since the design of irrigation systems depends to a large extent upon the infiltration characteristics of the soil. Many workers have contributed to the theoretical understanding of the infiltration phenomenon (Kirkham & Powers, 1972). However, very little work is available on the evaluation of infiltration into cracked soils. Measurement of infiltration into these soils poses a special problem. Depending on the degree of cracking, a fraction of the water added on the soil surface flows down through cracks and goes to waste. The water flowing through the cracks does not contribute to the moisture storage of the soil profile which may subsequently be used by the crops. Also, infiltration rates measured using ring infiltrometers are erroneous. In order to have an efficient design for an irrigation system, realistic estimates of infiltration characteristics for this type of soil are essential. In the present paper an attempt has been made to estimate the effective infiltration rate into such cracked soils. The procedvire suggested has been tested under limited conditions and found useful under field conditions. However, extensive field testing under various soil conditions is necessary before it can be recommended for general use.

Description: 〈div data-abstract-type="normal"〉〈p〉Despite the global importance of 〈span〉Capsicum〈/span〉 species, there is limited information on the indigenous endomycorrhizal fungal association in this crop. Therefore, the diversity and colonization patterns of arbuscular mycorrhizal fungi (AMF) in roots of Naga King chilli (〈span〉Capsicum chinense〈/span〉) were assessed during pre-flowering, flowering and fruit ripening growth stages under a sub-tropical shifting cultivation system of North Eastern India. All the roots examined had AMF colonization and the presence of 〈span〉Paris〈/span〉-type arbuscular mycorrhizal morphology is reported for the first time in 〈span〉C. chinense〈/span〉. A total of 11 AMF spore morphotypes were isolated from both field and trap culture soils. Maximum AMF spore density and root colonization were recorded during the pre-flowering and flowering stages, respectively. The influence of 〈span〉Funneliformis geosporum〈/span〉, individually or in combination with 〈span〉Pseudomonas fluorescens〈/span〉 and 〈span〉Azotobacter chroococcum〈/span〉, on growth and yield of 〈span〉C. chinense〈/span〉, was evaluated in a pot experiment using sterilized and non-sterilized soils. The application of AMF and 〈span〉P. fluorescens〈/span〉 to sterilized soil significantly increased the growth, flower and fruit production, and nutrient content of 〈span〉C. chinense〈/span〉. The highest growth rates and yields of 〈span〉C. chinense〈/span〉 in non-sterilized soils were achieved when AMF was combined with both 〈span〉P. fluorescens〈/span〉 and 〈span〉A. chroococcum〈/span〉. The results of the current study indicate the value of applying microorganisms to improve plant growth and performance in chillies. One of the mechanisms for this could be the facilitated assimilation of nutrients promoted by AMF and bacterial bioinoculants.〈/p〉〈/div〉

Description: SummarySimple mathematical models to predict leaching fractions and mean displacement depths of salts either uniformly distributed in the soil profile or surface applied have been derived from the solution of Peck's differential equation of salt balance. Predictions from these models are comparable with those obtained from Burns' equation and fit published data well.

Description: SUMMARYField studies were carried out to determine the sources of photosynthate for developing pods and to assess the effect of defoliation and flower removal at different stages on the performance of lentil. The leaves of flowering nodes were the primary source of assimilate to pods. Removal of 25–75% of leaves reduced seed yield by varying degrees depending on crop growth stage. The plants compensated for the loss of foliage to some extent, possibly through increased efficiency of the remaining leaves. One complete or 50% defoliation reduced seed yield to different extents at the vegetative, flowering, early pod formation and late pod formation stages, the greatest effect being seen at flowering and early pod formation. Plants compensated considerably by production of new leaves when defoliated at the vegetative phase. Increased moisture supply greatly enhanced the compensation ability of the lentil plants.Removal of all flowers up to 1–2 weeks after an thesis under unirrigated conditions and up to 3 weeks after anthesis in irrigated conditions did not adversely affect the seed yield. Flower removal beyond this period resulted in a significant reduction in seed yield. Little seed yield was obtained when flower removal was continued for either 6 or 8 weeks under unirrigated conditions. The plants compensated for the loss of earlier-formed flowers by setting pods from later-formed flowers. Compensation was greatly enhanced when the crop was irrigated during the reproductive phase. There was relatively little or no effect of the deflowering treatments on the number of seeds per pod or weight per seed. The flowering period of the deflowered plants was extended and their senescence was delayed. When 25% of the flowers were removed at different intervals during the reproductive phase, seed yield was not adversely affected. An increased intensity of flower removal decreased yield but the decrease was not proportional to the degree of flower removal. The plants apparently compensated by setting new pods.

Description: SUMMARYA general equation for predicting the movement of interacting and non-interacting solutes is proposed. Equations to predict the leaching fractions and mean displacement depth of linearly adsorbed solutes have been derived from the solution of the general equation. A simple equation which considerably reduces the experimental and analytical work has also been derived to evaluate the adsorption coefficient. The predicted adsorption coefficient compares favourably with published data.

Description: SUMMARYEquations to predict the leached fractions of initially surface-applied salts either with irrigation water or broadcast on the soil surface have been derived from the solution of the dispersion-convection equation. Predictions obtained from these equations compare well with observed leaching data of chlorides and nitrates. It is shown that the loss of fertilizers when applied with irrigation water is reduced compared with that of applying it by broadcasting. The use of equations for predicting soil salinization and leaching of surface-concentrated salts is also indicated.

Description: SummaryField investigations were carried out to study the effect of partial defoliation on dry-matter production and seed yield of urd bean. Partial defoliation during the vegetative and/or reproductive phase reduced seed yield. The severity of yield reduction was dependent on the stage of crop development and the degree of defoliation. The reduction of total dry-matter production by defoliation was accompanied by a decrease in crop growth rate and leaf/plant weight ratio. The net assimilation rate was higher in defoliated plants from 40 to 60 days after sowing. The reduction in seed yield due to defoliation was highly due to a reduction in the number of pods per plant, and also sometimes in the number of seeds per pod and in 100-seed weight.

Description: Despite the global importance of Capsicum species, there is limited information on the indigenous endomycorrhizal fungal association in this crop. Therefore, the diversity and colonization patterns of arbuscular mycorrhizal fungi (AMF) in roots of Naga King chilli (Capsicum chinense) were assessed during pre-flowering, flowering and fruit ripening growth stages under a sub-tropical shifting cultivation system of North Eastern India. All the roots examined had AMF colonization and the presence of Paris-type arbuscular mycorrhizal morphology is reported for the first time in C. chinense. A total of 11 AMF spore morphotypes were isolated from both field and trap culture soils. Maximum AMF spore density and root colonization were recorded during the pre-flowering and flowering stages, respectively. The influence of Funneliformis geosporum, individually or in combination with Pseudomonas fluorescens and Azotobacter chroococcum, on growth and yield of C. chinense, was evaluated in a pot experiment using sterilized and non-sterilized soils. The application of AMF and P. fluorescens to sterilized soil significantly increased the growth, flower and fruit production, and nutrient content of C. chinense. The highest growth rates and yields of C. chinense in non-sterilized soils were achieved when AMF was combined with both P. fluorescens and A. chroococcum. The results of the current study indicate the value of applying microorganisms to improve plant growth and performance in chillies. One of the mechanisms for this could be the facilitated assimilation of nutrients promoted by AMF and bacterial bioinoculants.