Abstract

The hydrogel is a soil conditioner able to retain water and plant nutrients. Hydrogel is commercially available as stockosorb/raindrop/agrosorb. Stockosorb releases water and nutrient to the plants when surrounding soil near root zone of plants starts to dry up, this was also observed in case of soils of Arunachal Pradesh, which are eroded, porous and gravely in nature. The soils vary from sandy loam to loamy sand with acidic in reaction with varying N: P: K status. The cultivated lands occur mostly in the hill slopes and few in valley. Horticulture is usually practised as a remunerative profession in the state. Citrus is the most occupied crop among the horticultural crops. Khasi mandarin (Citrus reticulata Blanco) is one of the important crops among citrus growers. Planting of citrus on steep hill slopes and lack of supplementary irrigation and application of nutrients, cause gradual decrease in their productivity. One of the mandarin orchards of the village Mirem was used for the experiment. The orchard is in a land having slope of 38%. The village is located in East Siang district of Arunachal Pradesh. The effect of stockosorb on the growth and yield of Khasi mandarin was evaluated. The experiment was laid out in randomised block design with three replications and seven treatments (T1–Control, T2–20 g of stockosorb, T3–40 g of stockosorb, T4–60 g of stockosorb, T5–80 g of stockosorb, T6–100 g of stockosorb and T7–120 g of stockosorb). The treatments were applied during December 2012 with application of recommended doses of N: P: K i. e. 450, 450 and 900 g, respectively, to each tree. Among the treatments, treatment T4 was found to be the best. Significant yield i. e. 283 fruits per tree was recorded for the treatment T4. This is the highest yield among all the treatments. The fruits from T4 also produced reducing sugar content as 7.16% and the ascorbic acid content of 106.6 mg/100 g. In case of the treatment T4, the WHC of the soil increased from 19.65 to 30.8%. This may be due to the fact that the soil was wet for a longer time increasing the microbial activity as well as reducing the fruit drop due to water stress. With respect to mean increase in tree height, treatment T4 was found to be superior among all the treatments. Moreover, with respect to growth of the tree, it was found that there was appreciable increase in the growth of the tree in all the treatments where stockosorb was used as compared to control. It was also observed that stockosorb also held available water for the plant up to 15 days.