One-year pot culture and two-year field trials on soybean cv.Willianms-82 were conducted on two different sowing dates in medium textured basic and salt free soil at ARI under the climatic conditions of Quetta. The study was aimed to assess the effect of different level of added fertilizer (T) with and without inoculation and sowing times on nodulation growth yield attributes and various biochemical components of mature soybean seeds. Six different doses (T2 to T7) of N fertilizer @ 23, 25, 75, 100 and 125 kg N ha-1 in combination with a constant dose of P and K fertilizer @60+30kg PK ha-1 were applied to both set of experiments respectively, whereas T1 was kept control. In addition to inoculums and fertilizer, a constant dose of FYM was also mixed with the soil (1:3) of pot culture studies. The experimental fields were laid out in a randomized complete block design (RCBD) with split-plot arrangement. The inoculums were assigned to the main-plots, while fertilizers were applied to the sub-plots Each sub-plot measured 2.25 X5.00 m and 2.50 X 2.50 m for the growing years 1996 and 1997 respectively.
Results pertaining to growth parameters revealed that in response to applied fertilizer the petiole length leaflet area and plant height in general significantly increased in early planting (EP) and non-significantly responded in late plantings (LP) while the inoculatlin response was generally nored as significant in both plantings. Whereas by comparing the grand mean values EP comparatively produced 7.48 70.11 and 39.73% greater petiole length leaflet area and plant height over LP experiments respectively. However in case of pot culture studies added FYM significantly improved these growth parameters.
Results also deciphered that fertilizer treatments significantly increased the grain yield in both plantings while inculum’s response was found as non-significant. Statistically a maximum grain yield (viz., 2364 and 3507 kg ha-1) was obtained for T-6 dose of fertilizer (i.e., 100+60+30 kg NPK ha-1) in both year fields respectively. Whereas by comparing the grand mean value EP comparatively produced 46.90% greater grain yields over LP crop. This suggests that planting date was the principal cause in increasing the grain yield in soybean under Quetta Climate.
Results further depicted that 100 seed weight pods plant-1 and pods contained various numbers of beans in relation to fertilizer and inculums treatments were found significant in EP and LP (only in 100 seed weight and sterile pods). Statisticall6y a maximum significant weight of 100 seed (14.28 g) and total number of pods plant-1 (53.39) were also recorded for T6 kdose of fertilizer.
The correlation coefficient ® studies revealed that in case of both year fields yield attributes generally exhibited highly significant positive correlation with their respective grain yield plot-1 while growth parameters showed insignificant association. Moreover, added FYM significantly improved the association of growth parameter and yield attributes with the grain yield of pot culture experiments.
The simple correlation coefficient ® studies deciphered that soluble protein of EP (without any concomitant loss in their oil) and oil contents (without any concomitant loss in their protein content) as well as soluble sugars of pot culture seeds were significantly and positively correlated with their grain yield plot-1 or pot-1.
Apart from these, the seed of each experiment was analyzed for their free amino acids lipase and urease activities moisture contents, mineral N (viz., No3-N NH4-N and N)2-N) PO4-P, K+, Na+, Ca+2, Mg+2, total Fe & Cu and Ci contents. These cations and anions were also correlated with each other as well as with their corresponding yields. The detail of the whole agronomical and biochemical results are being explained and discussed in the light of information given in the literature. In the end a general conclusions and suggestions for future planning are described briefly