The present thesis comprises six chapters. In Chapter 1 (Introduction), the importance of the problem “Study of the Effect of N, P and S Application on the Performance of Rapeseed-mustard”, has been discussed briefly. In view of the lacunae in the understanding of the problem, justifications have been put forward for undertaking the present work. Moreover, the logical basis of each of the four experiments undertaken has been mentioned briefly.

A pot experiment was conducted to study the effect of foliar spray of plant growth regulator triacontanol – a naturally occurring long-chain aliphatic alcohol – on growth, yield and quality parameters of two varieties (Hyb-SC-3 and Hyb-Himalata) of tomato (Lycopersicon esculentum Mill). Plants were sprayed twice with 0, 0.25, 0.5, 1.0 and 2.0 ppm aqueous triacontanol. Increasing levels of the growth regulator up to 1.00 ppm enhanced most parameters, including fruit yield, particularly of Hyb-SC-3.

Hyacinth bean (Lablab purpureus L.) is one of the important leguminous crops widely cultivated in many regions of the tropics and subtropics. Its seeds and pods contain as much as 20-28% protein and thus serve as a good source of vegetable proteins in human diets. The plant residue is used as a green manure. However, the crop yield is not high, and the low yield of the beans is attributed to the low levels of calcium (Ca) available in the soils.

Salinity stress affects many metabolic facets of plants and induces anatomical and morphological changes resulting in reduced growth and productivity. To overcome the damaging effects of salinity, different strategies of the application of nutrients with plant hormones are being adopted. The present study was carried out with an aim to find out whether application of calcium chloride (CaCl2) and gibberellic acid (GA3) could alleviate the detrimental effects of salinity stress on plant metabolism.

Commercial cultivation of linseed for both seed and fibre is not keeping pace with increasing demand for linseed products. Although, different strategies are being adopted to produce a dual-purpose linseed crop with good yield of seed and fibre, little progress has been achieved. The present study was carried out to investigate whether application of gibberellic acid (GA3) along with CaCl2 and/or MgSO4 could ameliorate the seed yield in three linseed genotypes ‘Parvati’, ‘Shekhar’ and ‘Shubhra’ without compromising the fibre production.