Elements of climate, phenology and soil moisture

In Figure 1 having the Tmax and Tmin (year average) and precipitation (ten sum) during crop growth is noted that the Tmax was between 33 and 37 °C and Tmin between 12 and 18 °C. The higher Tmax (37 °C) occurred in the first ten days after emergence (E) and then decreased as the season progressed crop. The lower Tmin (12 °C) occurred after the start of flowering (R1) and start fruiting (R2). The heat range for crop development is 5-35 °C, with an optimum around 22 °C (^{Benacchio, 1982}) Under these conditions the culture reached physiological maturity and considering the temperature as a non-limiting factor for the growth and development of the crop. Regarding precipitation is was 7 mm during the growing season because it usually rains in the region are presented in summer.

E= emergence; R1= beginning of flowering; R2= start fruiting; RH= physiological maturity. Huitzuco, Guerrero, Mexico. Fall 2011.

Figure 1 Ten-year average maximum temperature (T max), minimum (T min)) and decadal amount of rainfall during the growing season chickpea.  

The days occurrence of phenological phases were similar among treatments. Thus, the (E) occurred at 10 days after sowing (ddp), the initiation of flowering (R1) at 55 dds, dds R2 at 67 and RH to 118 dds. The GDD accumulated E was 213, in 1010 to R1, R2 of 1 225 and HR 2 295 °C d respectively. ETc accumulated physiological maturity (RH) was 380 mm.

In the Figure 2 shows that the residual moisture decreased as advanced crop development. This trend to a quadratic regression model was adjusted. At the beginning of the experiment 25% moisture (field capacity) and 118 days (end of the cycle) 2% (about permanent wilting point) it was recorded. According to the regression model, the reduction of moisture per day averaged 0.46%. During the development of visually crop plants it wilt not observed, which suggests that a tolerant crop limited moisture conditions. Which can be attributed to chickpea leaves secrete an aqueous solution composed of oxalic acid and malic capture humidity during the night, which could help supplement the water requirement for growth (^{Martínez and Calderón, 2005}).

E= emergence; R1= beginning of flowering; R2= start fruiting; RH= physiological maturity. Huitzuco, Guerrero, Mexico. Fall 2011.

Figure 2 The dynamics of soil moisture (%) during cycle chickpea.  

Total biomass and its distribution in plant organs

Accumulation BT present significant changes interaction effect D*N (Figure 3). With the combination D40-N0, D40D40-N50 and N100, respectively the MS grain, leaves, stem and leaflets increased by 47, 49, 50 and 48%, respectively, relative to N0-D80, D80 and D80-N50 -N100.

N0= no nitrogen; N50= 50 kg N ha^-1; N100= 100 kg N ha^-1. D40= row spacing of 40 cm; and D80= row spacing of 80 cm.

Figure 3 Total biomass and its distribution on the ground depending on the distance between rows and doses of N. Huitzuco, Guerrero, Mexico. Fall 2011. 

Moreover, the distribution of MS in plant organs was similar between treatments, which averaged 30% for stem, 30% for corn, 30% to 10% leaves and leaflets. This suggests the possibility that environmental variation related to changes in row spacing and N, was not as severe to affect the distribution of MS in chickpea.

As for the interaction D*N, Figure 4 shows that the response to interaction BT adjusted to a quadratic polynomial. Thus in D40, the response BT to N was higher, since for every kg N ha^-1 that BT was applied increased by 7.6 g m^-2, whereas D80 increased by 3.8 g m^-2. Also, most BT was generated with D40-N100, with increases of 56% compared to N0-D80 (Figure 3). Such a response is determined by a higher growth stimulated by plant canopy N, by its effect on leaf expansion (^{Escalante, 1995}, ^{Escalante, 2001}) and increased ground cover planting caused by short distances, leading to greater radiation interception and a more efficient use of water. Similar results were reported in sunflower (^{Aguilar et al., 2005}).

D40= row spacing of 40 cm and D80= distance between rows of 80 cm.

Figure 4 Response of total biomass (BT) to the distance between rows according to the dose of nitrogen, total biomass interaction Huitzuco x N., Guerrero, Mexico. Fall 2011.  

Harvest index

Harvest index (IC) showed significant changes as a result of D, N and interaction D*N (Table 1). With the IC D40 was superior to D80, which is attributed to the efficient use of all resources such as water and nutrients. With regard to N, with the IC N100 increased by 8% and 10% compared to N0 and N50, respectively. Similar trends were reported in sunflower (^{Olalde et al., 2000}). In relation to interaction D*N, the highest IC met D40-N100 (4.2% from D80-N0). These results indicate that the N, generating increased demand for fotoasimilados by increased production of pods and grain rises MS allocation to these structures and the high population density makes more efficient use of resources including water and nutrients (^{Olalde et al., 2000}; ^{Escalante and Rodriguez, 2010}). Similar results were found ^{Saxena and Johansen (1988)}, who in chickpea cultivars cold tolerant reported IC 32%, close to the average value of this study.

Grain yield and its components

The nitrogen response according to the distance between the spinneret RG, a second degree polynomial model is adjusted. With D40 response in the RG up to 100 kg N ha^-1 found (230 g m^-2); whereas D80, the highest RG (140 g m^-2) was achieved with 50 kg N ha^-1 (Figure 5). In this sense, ^{García (1997)} obtained a yield of 3 t ha^-1, seed from 15 november to 15 december residual moisture.

D40= row spacing of 40 cm and D80= distance between rows of 80 cm.

Figure 5 Response grain yield (RG) to the distance between rows according to the dose of nitrogen. Huitzuco, Guerrero, Mexico. Fall 2011. 

In the Table 1 shows that the RG and its components, number of pods (NV), weight of hundred grains (P100G) and number of grains (NG) showed significant changes due to the D, N and interaction D*N. With D40, the RG increased 53 g m^-2, 257 m^-2 NV, 6.6 g P100G and NG 361 m^-2 in relation to D80. With N100, the largest RG, NV, P100G and NG was achieved. Regarding the combination D*N, the greater RG, NV, P100G and NG-D40 was achieved with N100, with increments of 45, 46, 35 and 48% respectively in relation to D80-N0. According to the statistical analysis of the main factors, the most influential factor in this response was the distance (Table 1). This behavior is attributed to the more efficient use of inputs for crop growth. In addition, under conditions of residual moisture, by planting in narrow rows and the resulting increase in population density, generates more ground cover from the early stages of crop development, this reduces water loss by evaporation, so there greater availability of water and time to be used by the crop (^{Roy and Sharma, 1986}).

As for the factor N, the initial level was low (0.08%), resulting in the lowest RG N. failing to apply this necessitates the provision of that nutrient in these conditions to achieve an acceptable RG. In this regard in India, reported increases of up to 30% RG applying 100 kg N ha^-1 (^{Roy and Sharma, 1986}). In bean (Vicia faba L.), significantly increases NV, NG and consequently in the RG with application of 99 kg N ha^-1 (^{Escalante and Rodriguez, 2010}). ^{Danso and Eskew (1984)} emphasize the importance of N as a factor of increase to 75% in the RG of agricultural crops.

Relationship between grain yield and its components

In Table 2, showing the relationship between the RG and components as NG, and P100G NV, it shows that the NG was more related to RG, followed by NV. This indicates that to raise the RG should increase the size of the demand for photosynthates such as the NG and NV (^{Escalante and Rodriguez, 2010}), which can be achieved through crop management practices, among them the distance between rows sowing and nitrogen supply.

Efficiency in water use

By reducing the distance between rows of planting more ground cover is achieved from the early stages of crop development (^{Escalante and Rodriguez, 2010}). This means more water available for the crop to reduce evaporation losses, generating US higher (Table 3). With the D40 EUAB EUAG and was higher by 0.27 and 0.88 g m^-2 mm^-1, for D80. With N the EUAG and EUAB rose by 0.25 and 0.71 g m^-2 mm^-1 in relation to the control (without fertilization).

When handling high population density by reducing the distance between rows and N application it has fast effect of N coverage and increase the crop canopy so the efficiency of water increases (^{Escalante, 2001}). As for the interaction D*N, most EUAG and EUAB recorded with D40-N100, while the lower efficiency D80-N0. About residual moisture under conditions ^{Zhang et al. (2000)} with supplementary irrigation EUAB recorded values of 8.7 g m^-2 mm^-1 and EUAG 3.2 g m^-2 mm^-1. It is attributed to higher efficiency which is higher water availability.

Profitability

In studies where the inorganic fertilization involves an economic analysis required by the high cost of its acquisition and application. In the Table 4 having the economic analysis for the RG, it is observed that the D40-N100 treatment generated more RG, the highest total cost (CT) and the highest net income (NI). However, higher earnings per invested peso (GPI) was achieved with D40-N50 and the lowest with D80-N0. The application of inorganic N increased GPI in $0.30 for D40-D80-N50 and N50 compared to treatment without N. In crops such as sunflower, with N100 has also achieved the highest net income (^{Olalde et al., 2000}). Moreover, even when not count with financing for the purchase of fertilizer, by shortening the distance between rows of plants you can achieve considerable IN as in the case of D40-N0 treatment (Table 4).

Finally, the results indicate that N and D short chickpea had higher EUAG, EUAB, BT, NV, P100G, NG, IC and because of this higher RG. It's response was superior to D N, which is attributed largely to reducing the distance between rows using inputs efficiently is because most ground cover early stage culture is generated and there reducing evaporation, so that there is more water available is used by the crop. The best combination in terms of production was D40-N100, which also generated the highest economic gain (IN= $ 20 640). The greatest response Chickpea a combination of short and high fertilization is attributed to increasing population density is maximized space and nitrogen requirement is higher, so the nitrogen fertilization is achieved chickpea increased production under conditions of residual moisture.