MORPHOPHYSIOLOGY AND PRODUCTIVITY OF MUSTARD IN *-f RELATION TO GIBBERELLIC ACID AND SULPHUR APPLICATION MOHD. MOBIN Abstract of the thesis, submitted to the Aligarh Muslim University, Aligarh, India for the degree of Doctor of Philosophy in BOTANY The present thesis comprises of six chapters. In Chapter 1, the importance of the problem and the lacunae in the understanding of the problem and justifications have been put forward for enterprising the present work. In Chapter 2, a review of the work done on individual and of combined effect of plant growth regulators and sulphur nutrition on crop growth and development have been envisaged. Chapter 3 deals with the details of material and methods employed for the four field experiments conducted and relevant meteorological and edaphic data have been given In Chapter 4, the results found significant at P < 0.05 on performing statistical analysis according to the design of the experiment have been recorded in detail and the significant resuhs have been discussed in the context of earlier findings in Chapter 5. Chapter 6 deals with the summary which was followed by bibiliography. Four field trials were conducted on Brassica juncea L. Czern &. Coss. cv Varuna during rabi season at the Farm of Aligarh Muslim University, Aligarh, India fi-om 1995-97.
Experiment 1 (1995-96) was conducted according to factorial randomised block design to establish the most suitable duration (8 or 12 h) for soaking of mustard (Brassica juncea L.) var. Varuna seeds in GA3 solutions of concentrations of 0, lo"*, 10'', and 10 M on performance of mustard. Soaking concentration of lo"^ M GA3 and soaking duration of 8 h was found to be the best in comparison to any other combinations of the treatment for most of the parameters studied. In growth parameters, soaking of seeds for 8 h in 10"^ M GA3 concentration increased the plant height, leaf area and plant dry weight. Further enhancement in concentration, i.e., 10"', 10"^ M or soaking for higher duration i.e. 12 h could not improve these parameters. The distribution of dry weight from source to sink (pods) was highly efficient in 10"^ M GA3 concentration as was evident from higher pod dry weight. Crop growth rate was impressively enhanced with soaking of seeds in 10"^ M GA3 for 8 h at early growth stages, i.e., 0-40 DAS interval and 60-80 DAS interval. However, relative growth rate and net assimilation rate got declined with GA3 soaking. Specific leaf weight increased and leaves became thicker at initial stage upto 80 DAS in treatment 10 M GA3 soaked seed and became equivalent to that of control treatment at 100 and 120 DAS. In photosynthetic parameters, chlorophyll content, rate of photosynthesis and photosynthetically active radiation was increased with 10"^ M GA3 soaking of seeds for 8 h. In biochemical parameters soaking of seeds for 8 or 12 h and in all concentrations of GA3 resuhed in equal values for nitrogen, phosphorus and potassium content. Uptake of N, P and K were, however, enhanced by 8 h soaking treatment in 10"^ M GA3. In yield parameters, number of pods and seed yield was increased which directly boosted the oil yield. The quality parameters; oil content, acid, iodine and saponification values remained unchanged with any of the treatment. The
interaction effect of GA3 soaking concentrations and soaking duration was found to be non significant for almost all the data. Experiment 2 (1995-96) was conducted according to factorial randomized block design. The aim of this experiment was to ascertain the effect of single foliar spray of 0, 10"*, 10"' and 10"^M GA3 at 40 and 60 DAS, or double spray in equal splits of 0, 10"'^ 10"'" and 10"^ GA3 both at 40 and 60 days. It was noticed that the effect of GA3 spray at 40 DAS and two equal splits of GA3 spray at 40 and 60 DAS were at par for all the parameters at final stages. The spraying concentration of lo'^m GA3 at 40 DAS was registered best for most of the parameters investigated. Almost all the growth characteristics and photosynthetic parameters were influenced favourably with spray of 10"'M GA3 at 40 DAS and the response was identical to that of soaking experiment (Experiment 1). In biochemical parameters, no difference was found between the spraying concentrations of GA3 and water for the concentrations of the nutrients. However, nutrients (N, P, K) uptake was enhanced by the treatment. Yield attributing parameters, seed yield and oil yield were recorded highest for 10"'M GA3 sprayed plants at 40 DAS. The interaction effect was found to be significant for only few growth and photosynthetic parameters at 60 and 80 DAS samplings. Experiments 3 and 4 (1996-97) were conducted simultaneously according to factorial randomized block design to assess the effect of soaking of mustard seeds for 8h (selected in Experiment 1) in 0, 10"*, 10"' and 10"^M GA3 along with five levels of basally applied elemental sulphur 0, 25, 50, 75 and 100 kg/ha (Experiment 3) and GA3 spraying of 0, 10"*, 10"' and 10"^M at 40 DAS (selected in Experiment 2) along with five basal levels of sulphur 0, 25, 50, 75 and 100 kg/ha (Experiment 4). The parameters studied in
these experiments were same as in earlier experiments. But in biochemical parameters content and uptake of sulphur were also determined. In general, it was observed that at lower level of sulphur (25 or 50kg S/ha), soaking (lo'^m GA3) or spraying (10*'M GA3) of GA3 elicited beneficial effect on almost all parameters, but at higher levels of sulphur (75 or 100kg S/ha) and soaking or spraying of GA3 did not show any beneficial effect. In Experiment 3 seed soaking in 10"*M GA3 for 8 h improved growth, photo synthetic, biochemical and yield parameters. In this Experiment, it was also found that application of 25kg S/ha registered maximum plant height, larger canopy and thereby higher biomass accumulation at all stages of sampling. Crop growth rate was immensely improved with 25kg S/ha while RGR and NAR were found to be maximum in higher levels of sulphur. Pod dry weight was highest in 25kg S/ha treatment which reflects the efficient translocation of dry matter towards sinks (pods). In photosynthetic parameters, chlorophyll content, rate of photosynthesis and photo synthetically active radiation were found to be highest in sulphur level 25 kg S/ha. However, at higher levels of sulphur rate of photosynthesis and chlorophyll content was decreased at all sampling days, but PAR was higher at 100 DAS. In biochemical parameters, nitrogen and sulphur content was found to be increased with increasing levels of sulphur while potassium and phosphorus content remain unaltered. Uptake of nitrogen, phosphorus, potassium and sulphur was found to be highest in 25kg S/ha treatment. In yield parameters pod number, seed yield biological yield and harvest index were found to be maximum in 25kg S/ha treatment. This had direct implications on the oil yield which treads the similar path to that of seed yield. In quality parameters, quality of oil got improved by lowering the acid value and
increasing the saponification value of the oil with the application of 25kg S/ha, where former considered to be good for oil keeping quality while latter for digestibility and soap making quality. The interaction effect was found to be significant for most of the parameters, where lower levels of sulphur, showed significant difiference and higher values than individual effects. In Experiment 4, the response of all growth, photosynthetic, biochemical, yield and quality parameters were similar for various sulphur levels, lo'^m GA3 and its interaction to that of Experiment 3. The perusal- of the pooled analysis of the data recorded for Experiment 3 and Experiment 4 and fitting the regression curve for seed yield of these two experiments, it emerged that the trend of response to GA3 in these experiments were similar. The option of selecting the mode of application of GA3 (through seed soaking or foliar spray) depends on one's own limitations and local conditions rr ^\\ ; I Ace. No ^ ^ I