Cassava starch extracted from six varieties at different period of growth was examined for various physiochemical properties. The granule size increased in all the six varieties upto 6th month from time of tuber initiation and thereafter remained almost constant. The amylose content and reducing values did not vary much at different stages of growth. The swelling volume and swelling power of starch showed large variations particularly after 10th month. Such changes of four varieties were not noticed in other varieties. Associative binding forces of starch molecules largely determine the stability characteristics of starch under varied environmental conditions.

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S U M M A R YSource-sink relations in cassava were investigated following reciprocal grafting among three cultivars of different yield groups. Both rootstock and scion had significant effects on net assimilation rate and tuber yield, demonstrating that both sink capacity and source activity are important in achieving maximum tuber yield. The scion had no effect on tuber dry matter percentage and starch content of the grafts but the hydrocyanic acid content of the tuber was significantly influenced by both rootstock and scion.T. Ramanujam y S. P. Ghosh: Investigaciones sobre las relaciones fuente-patron en la mandioca usando el injerto reciproco. R E S U M E NSe investigaron las relaciones fuente-patron en la mandioca tras el injerto reciproco entre tres cultivares de grupos de distinto rendimiento. Tan to el rizoma como el esqueje tuvieron efectos significativos sobre elritmo de asimilacion neta y el rendimiento de tuberculos, lo que demuestra que tanto la capacidad del patron como la actividad de la fuente son importantes para lograr el maximo rendimiento de tuberculos. El esqueje no ejercio ningun efecto sobre el porcentaje de materia seca de tuberculos y el contenido de fecula de los injertos pero el contenido de acido cianru'drico del tuberculo se vio afectado de modo significative) tanto por el rizoma como por el esqueje.

Tomato (Lycopersicon esculentum Mill.) growth, cultivation and its productivity are adversely influenced by severe environmental pressures. Several environmental abiotic factors that are limited not only to drought, salinity, temperature and heat but also to mechanical stress affect tomato yield and productivity. Salinity is a persistent problem throughout the world that affects soil properties. Further, tomato productivity due to salinity stress is affected at all stages of plant development. Seed priming, a method to alleviate salinity stress is an effective technique that can improve performance and growth. It is a method that permits controlled hydration of seeds thereby, maintaining metabolic activity, without allowing the protrusion of the radicle. Mechanical conditioning, a term applied to plant stimulation by tactile stimuli through various methods like touching, brushing, or rubbing the plant material, is another environmentally friendly and simple method to regulate plant growth and also stress tolerance. Therefore, the mechanical conditioning practice primes plants for enhanced plant growth and also allows plants to defend against an impending stress factor. These two methods can be developed into successful production practices. In this chapter, we summarize current knowledge of seed priming and mechanical conditioning for plant growth, cross-tolerance and plant productivity improvement.