The effect of using diatomite on yield and yield component of chickpea (Cicer arietinum) under different irrigation regimes

Moisture stress is one of the most important limiting factors which can affect crop production in semi-arid regions. Proper management and application of advanced techniques to maintain soil moisture and improve soil moisture holding capacity in the soil are effective in increasing water use efficiency and improving water resource utilization. Due to the importance of chickpea as a source of protein and the irreparable damage of moisture stress to yield of chickpea, the selection of methods that can increase the tolerance of the plant to moisture stress is very important. Recently, the use of superabsorbent has increased due to the ability to absorb and maintain water and consequently increase water use efficiency in the soil. Diatomite, as a superabsorbent, is a unique natural material with interesting features including very fine structure, low mass density, high porosity, high specific surface, chemical neutrality and high silica content. Therefore, the aim of this study was to determine the proper amount of diatomite to obtain maximum chickpea yield under moisture stress conditions. 

In order to investigate the effect of diatomite on yield and yield component of chickpea under different irrigation regimes, an experiment was conducted in Khaf in the year 1396-1397. This research was conducted as split plot based on randomized complete block design with three replications. The main factor of irrigation regimes was five levels (dry farming, full irrigation, one irrigation in vegetative stage, one irrigation in reproductive stage, two irrigations: one vegetative stage and one reproductive stage) and factor the subdivisions of diatomite were in three levels (0, 3.5 t/ha and 7 t/ha). Each plot has 6 cultivating lines 30 cm long and 3 meters long. In this experiment, diatomite was placed at a depth of 20 cm (maximum root zone density) under seed. The cultivation was carried out manually on the fifth of March with a density of 45 plants per square meter and a depth of 5 cm. In flowering after full yellowing of chickpea pods, number of pods, number of seed in pod, 100 seed weight, percentage of pod unfilled, seed yield and biological yield were measured. Harvest was calculated by dividing the seed yield into biological yield and multiplying it by 100.

 The results showed that changing the irrigation regime from full irrigation to dry farming caused a decrease in the quantitative traits studied. The lowest seed yield (318.54 kg/ha) and biological yield (725.44 kg/ha) were obtained in dry farming treatment. Application of diatomite under different irrigation regimes increased all evaluated traits and seed yield. The highest seed yield (1745.67 kg/ha) was obtained in irrigation treatment in vegetative and reproductive stages and consumption of 7 ton/ha of diatomite and the lowest amount (363.97 kg/ha) was recorded in dry farming without diatomite application. Also, application of 7 ton/ha of diatomite compared to non-application of diatomite increased by 29, 29, 77 and 39% in irrigation regimes including dry farming, one irrigation in vegetative stage, one irrigation in reproductive stage, two irrigations including stage, respectively. Vegetative and reproductive were in the trait of seed yield. Based on the results of interaction effects in irrigation treatment in vegetative and reproductive stage and other low irrigation treatments including irrigation in vegetative stage, irrigation in reproductive stage and dry farming application of 3.5 ton/ha diatomite with application of 7 ton/ha of diatomite in all studied traits in a statistical group it placed; Therefore, it can be said that the use of 3.5 ton/ha diatomite is the most appropriate amount in increasing the yield of chickpeas under low irrigation regimes. 

Generally, the results showed that the amount of irrigation water had a significant effect on yield and yield components of chickpea, thus reducing irrigation water in the treatments of two irrigations: one vegetative stage and one reproductive stage, one irrigation in reproductive stage, one irrigation in vegetative stage and dry farming in compared to the full irrigation treatment, it reduce 37, 63, 81 and 86% in seed yield, respectively, and this decreasing trend in other measured traits was observed. At the same time, reducing the amount of irrigation water increased the percentage of pod unfilled. However, the negative effects of reduced irrigation water can be reduced by using diatomite. The result showed that the application of 3.5 ton/ha diatomite at different irrigation levels in all measured traits didn't differ significantly from the application of 7 ton/ha of diatomite. Based on this, it can be said that the application of 3.5 ton/ha is the optimal amount. In general, using advanced methods such as using diatomite as a super absorbent while saving the cost of crop production in dry areas, by maintaining and storing moisture in the soil and improving water permeability in the soil can be an effective step in order to exploit limited water resources and increase seed yield.