| Guar (Cyamposis tetragonoloba L.) seed is an important source of galactomannan gum used in food, industrial and medical products. High efficient production mode is vital problem in farming. The effect of nitrogen and potassium fertilizer on guar seed yield and quality is one of the key tasks nowadays. Soilless culture, field culture and pot-culture were used in the trial system, the mechanism of galactomannan accumulation in guar seed was studied in the physiological, ecological, and enzymatic point of view. The relation of crop with culture system was discussed, and mathematical models were established on guar development with seed yield and guar gum content with different N and K level treatments. The results were follow:1 Effect of N and K fertilizer on seed yield and certain metabolism of guar1. The highest seed yield was got under N 40 kg hm-2 + K2O 90 kg hm-2 treatment. Seed yield was in coincident with the correlation model: y = 1.2110 x1+ 5.0175 x2 + 0.6074 x3 - 0.4029x4 - 0.7715 x5 - 4.9697,r2 = 0.9841. (x1 ,chla content in the leaves of 65 d old plantsï¼›x2 ,NR activity in the leaves of the 50 d old plantsï¼›x3 ,Pn in the leaves of 87 d old plantsï¼›x4 ,chla content in the leaves of 88 d old plantsï¼›x5 ,Pr content in the roots of 87 d old plants). The Pn in the 35 d, 50 d and 65d old plants was well correlated with the chlorophyll a in the same plant age, the correlation index was 0.8302, 0.8646 and 0.9882 respectively. The correlation models were as follows: y = 1.7133 x - 1.8719, r2=0.6892 (for the 35 d old plants ), y = 0.9668 x + 9.1907, r2=0.7476, (for the 50 d old plants), y = 2.3829 x + 3.7282, r2=0.9647 , (for the 65 d old plants).2 Effect of N and K fertilizer on Carbon metabolism of guar2.1 Effect of N and K fertilizer on sucrose phosphate-synthase (SPS) activity of guarThe trends of the average sucrose phosphate-synthase (SPS) activity went down since the 50th day. Higher N level was concomitant with lower SPS activity in the early growth stage, suggested that the higher N level caused the decrease in the maximum SPS activity was, hence retarded maximum peak. Effects of K level on SPS activity was less than that of N, but there was difference among different K levels, SPS activity was the lowest in thetreatment with K2O 120 kg hm-2 all the while. Meanwhile it was slightly higher in the K2O 60 kg hm-2 level than in the K2O 90 kg hm-2 level before the 65th day, and it was lower than the latter afterwards.2.2 Effect of N and K fertilizer on sucrose synthase (SS) activity of guarThe sucrose synthase activity was in single peak trend during the whole growth period. The maximum peak was delayed with the additional of N fertilizer. The maximum peaks of SS activity were at the 50th d, the 55-65th d and the 65th d under N 20, N 40 and N 60 kg hm-2 treatments, respectively, while the maximum value of SS activity were lower accompanied by the increase of N level. The SS activity treated with K 90 kg hm-2 was the highest, and the difference was significant between K60 and K120 kg hm-2 treatments. The treatment with 90 kg hm-2 K was the feasible dosage, which was the most benefit for the SS activity.2.3 SS and SPS characteristic of guarAs to the trends of guar seed development, SPS and SS activity decreased from the beginning of the seed development. The SS activity in the seeds was well correlated with that of SPS activity in the seeds, which could be expressed by the following equation: y = 0.7697 x +12.158, r2 = 0.8316. Sucrose content in the pod was negative correlated with that in seeds. SPS activity in the leaves was higher than SS before the 65th, whereas lower than SS afterwards.2.4 Composition of saccharide in the pod and seed of guarThe mainly detected sugar in the pod were pentose, rhamnose, arabinose, Mannitol, galactose, myoinositol, and raffinose. Trice of fruit and glucose were also detected. The primary soluble sugar detected in the seed were pentose, arabinose, myoinositiol, sucrose, raffinose, and dissaccharide â…¡. The hot water extracted p...
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